back to indexThe Science & Health Benefits of Deliberate Heat Exposure | Huberman Lab Podcast #69
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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we are talking about the science of heat,
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and more specifically, the science of heating, the verb,
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meaning how our body heats up
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from both the outside and the inside.
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Heat is a remarkable stimulus,
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meaning when we are in a hot environment,
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it has a profound effect on our biology.
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And heating up from the outside,
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or as you'll soon learn from the inside,
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has a profound effect on many different aspects
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of our health, including our metabolism,
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both in the immediate and long-term, our cognition,
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meaning our ability to think more or less clearly.
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And if you're immediately thinking
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that heating up makes you less capable of thinking,
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Heat applied properly as a stimulus
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can engage certain neurochemical systems
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in your brain and body
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that can allow your brain to function far better.
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We will talk about those data today.
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So we're going to talk about the science of heat and heating,
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both in terms of their mechanisms,
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and as I know many of you are interested in,
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the tools related to the use of heat,
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things like sauna, how often to do sauna,
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how long to be in the sauna,
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how hot to be in the sauna for particular goals and outcomes.
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We're also going to talk about the very exciting new science
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around local heating,
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that is the use of heat applied to specific areas
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of the body in order to heal or improve tissues
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at that location that you are heating,
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as well as your biology and health overall.
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In fact, we are going to talk about
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one very recently published paper
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that came out in the journal Cell.
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Cell is one of the three apex journals,
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meaning three of the most competitive,
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most rigorous scientific journals.
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Those are Nature, Science, and Cell.
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This particular paper was published in Cell,
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and I will go into it in more detail later.
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But basically what this paper shows
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is that by locally heating up skin and fat,
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you can change the identity of certain fat cells
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at that location and elsewhere.
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We have three kinds of fat, white fat,
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beige fat, and brown fat.
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And as you will learn more about soon,
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white fat is not very metabolically active.
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It's more of a fuel reserve.
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It's what we typically think of as blubbery fat.
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Beige fat and brown fat are rich in mitochondria,
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and those mitochondria provide a sort of furnace
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or heating mechanism for your entire body
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and increase your metabolism and the burning of white fat.
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So in other words,
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having more beige fat and brown fat is a good thing.
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And it turns out that the proper application of heat
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to specific areas of your body
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can increase the conversion of white fat to beige fat.
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In other words, turn an innocuous fuel source
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into a metabolically active tissue
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that can help you burn off more white fat.
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I think many people are going to be interested in this paper
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and the tools that emerge from this paper.
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It's a fascinating set of findings
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that actually emerged from my understanding
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of the biology of burn and people who receive intense burns.
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And that is not what I'm going to recommend to you
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as a tool, of course,
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but understanding a little bit about how burns impact
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our biology and health
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has allowed these pioneering researchers
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to develop new tools to combat obesity
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and metabolic disorders,
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and that you can apply for basic things like fat loss.
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I'm pleased to announce that the Huberman Lab Podcast
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is now partnered with Momentous Supplements.
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Our motivation for partnering with Momentous
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is to provide people one location where they can go
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to access the highest quality supplements
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in the specific dosages that are best supported
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by the scientific research
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and that are discussed during various episodes
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of the Huberman Lab Podcast.
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If you go to livemomentous.com slash Huberman,
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you will see those formulations.
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I should mention that we are going to add more formulations
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in the months to come,
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and you will see specific suggestions
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about how best to take those supplements,
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meaning what dosages and times of day,
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and in fact, how to combine those supplements
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with specific behavioral protocols
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that have been discussed on the podcast
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and are science supported
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in order to derive the maximum benefit
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from those supplements.
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And many of you will probably also be pleased to learn
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that Momentous ships not just within the United States,
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but also internationally.
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So once again, if you go to livemomentous.com slash Huberman,
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you will find what we firmly believe
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to be the best quality supplements in the precise dosages
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and the best protocols for taking those supplements
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along with the ideal behavioral protocols
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to combine with those supplement formulations.
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I'm pleased to announce
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that I am hosting two live events in May, 2022.
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The first live event will take place in Seattle, Washington
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The second live event will take place in Portland, Oregon
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Both are part of a lecture series entitled
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The Brain-Body Contract,
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during which I will talk about science
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and science-based tools,
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many of which overlap with the topics covered
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on the Huberman Lab Podcast,
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but most of which will not
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and will be completely new topics and tools
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never discussed publicly before.
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Both live events will also include
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a question and answer period
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during which you the audience can ask me questions directly
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about any aspect of science or science-based tools
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and I will attempt to answer them.
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Tickets for the two events,
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again, Seattle on May 17th and Portland on May 18th
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are both available at HubermanLab.com slash tour.
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Before we begin, I'd like to emphasize that this podcast
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is separate from my teaching and research roles at Stanford.
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It is however, part of my desire and effort
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to bring zero cost to consumer information about science
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and science-related tools to the general public.
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In keeping with that theme,
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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Element.
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Element is an electrolyte drink that has everything you need
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and none of what you don't need, meaning sugar.
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It has electrolytes and the main electrolytes
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are sodium, potassium, and magnesium,
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which you need in the proper ratios
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in order for your brain and body to function correctly.
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Element was designed to get you the proper ratio
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of electrolytes in order to optimize mental
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and physical performance.
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People out there with pre-hypertension and hypertension,
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of course, should be cautious
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about increasing their sodium intake,
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but many people can actually benefit
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from increasing their sodium intake,
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both for health and for performance.
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Element contains a science-backed electrolyte ratio
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of 1000 milligrams, that's one gram of sodium,
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200 milligrams of potassium, and 60 milligrams of magnesium.
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I consume Element when I first wake up in the morning,
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during exercise, and after exercise,
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and sometimes, again, if I've been sweating profusely,
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for instance, after doing a sauna
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or taking a run on a hot day, things of that sort.
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If you'd like to try Element, you can go to Drink Element,
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that's lmnt.com slash Huberman
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to claim a free Element sample pack.
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You only cover the cost of shipping.
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Again, that's Drink Element, lmnt.com slash Huberman
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to claim a free sample pack.
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Today's episode is also brought to us by Inside Tracker.
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Inside Tracker is a personalized nutrition platform
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that analyzes data from your blood and DNA
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to help you better understand your body
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and help you reach your health goals.
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I've long been a believer in getting regular blood work done
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for the simple reason that many of the factors
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that impact your immediate and long-term health
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can only be analyzed from a quality blood test.
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There are a lot of blood and DNA tests out there,
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So it not only gives you information
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it gives you directives as to how to improve your health.
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If you'd like to try Inside Tracker,
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go to insidetracker.com slash Huberman
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That's insidetracker.com slash Huberman to get 20% off.
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Today's episode is also brought to us by Roca.
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Roca makes eyeglasses and sunglasses
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that are the absolute highest quality.
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I spent a lifetime studying the visual system.
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I can tell you that your visual system
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It allows you to do things like move
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from a shady area outside to a sunny area outside
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A lot of sunglasses and eyeglasses are not designed
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and enter the code Huberman at checkout.
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Okay, let's talk about heat.
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More specifically, let's talk about the biology
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of heat and heating and the health benefits
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and tools related to heat and heating.
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The first question that we have to answer
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is how do we heat up?
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And the answer to that question is we heat up two ways.
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We heat up from the outside,
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meaning the things that we come into contact with,
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the clothing that we put on our body,
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whether or not there's heat in the room
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or whether or not it's cold outside or cold in a room,
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and we heat up from the inside.
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Our body has the capacity to generate more heat
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or to cool down, meaning to turn off the heating process.
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And it can do that in ways
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that match the external environment.
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The simplest way to think about this
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is that we actually have two body temperatures.
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People will say, oh, what's body temperature, 98.6.
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That's actually not true.
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Body temperature varies between individuals.
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It varies across time of day within individuals.
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And at every point across your entire lifespan,
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you have two distinct temperatures.
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One is the temperature on your skin,
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what scientists call your shell,
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and the temperature of your core,
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your viscera, meaning your organs,
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your nervous system, and your spinal cord.
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And as you can imagine,
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the temperature of your core is always higher
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than the temperature at your surface.
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So the important thing to know
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is that you have a temperature at your shell
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and a temperature at your core.
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Now you don't need to know exactly
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what those temperatures are in most cases,
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but it is vitally important to understand
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that you have those two temperatures
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and that your brain is constantly sending out signals
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to your body as to whether or not it should heat up
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or cool down depending on the temperature of the shell,
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which makes total sense.
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This is a lot like a thermostat in a room,
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which is essentially paying attention
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to how cold or hot it is,
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and then sending signals to the heating or cooling system
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to either heat up the environment
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or cool down the environment
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depending on the temperature in that environment.
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Your brain has neurons that send signals
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to other cells in your body
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and deploy the release of chemicals in your brain and body
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to heat you up when you are too cold
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and to cool you down when you are too hot.
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So if you can understand that you have two body temperatures,
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one at your shell, the surface,
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and one at your core inside,
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and that your body and brain are always trying
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to balance those two temperatures in the appropriate way,
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well, then you're halfway there
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to understanding the biology
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of thermal regulation and heating,
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and you'll be a lot further along
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in understanding how specific tools can be used
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to improve metabolism or improve cognition, for instance.
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In fact, later you will learn
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that one way that you can heat up
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is by cooling down the surface of your body.
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If I were to throw a cold towel, ice cold towel
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onto your torso right now and ask you,
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well, how do you feel?
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You'd say, oh, that's cold, that's chilly.
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However, because your brain is acting
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like a bit of a thermostat,
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as the surface, the shell of your body felt cool,
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it would make sense that that thermostat
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would activate biological mechanisms
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that would heat up your core.
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Similarly, if I were to put you into a very hot environment,
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you'd say, oh, wow, it's really, really warm in here,
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but your brain and your body
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would go through a lot of effort
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to activate mechanisms to cool you down.
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So anytime we're talking about heat,
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meaning deliberate heat exposure, things like sauna,
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it's very important to understand not just the stimulus,
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how hot something is, how long you're in a sauna, et cetera,
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but the effect that has on your shell and on your core.
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If you can understand that, you can design protocols
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that are literally perfect for your goals.
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And as a final point about this,
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if you want to develop the best tools,
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leveraging heat for your biology and health and performance,
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you want to understand heat as a process, as a verb,
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as heating, not just heat,
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because there's the temperature that you are at
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before you encounter the heat stimulus,
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before you get in the sauna, for instance,
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during the heat stimulus, so while you're in the sauna,
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and then afterward.
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Everything in biology is a process.
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So as you'll soon learn,
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there is a specific sauna protocol that can allow you,
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can allow anybody in fact,
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to increase the amount of growth hormone
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released into their brain and body 16 fold.
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That's right, 16 fold.
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However, it involves shifting from a hot environment
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to a cool environment, to a hot environment,
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to a cool environment, over and over and over again,
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over a very short period of time,
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because it engages a switch, a process that compounds,
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it builds on itself to increase growth hormone
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further and further.
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In fact, if you were to just get into a sauna
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for a very long period of time and crank up the temperature
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to match the exact temperature that was used in that study,
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you would not experience those increases in growth hormone.
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It really is the transition between hot
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and cool temperatures that engage the process
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of heating and reheating over and over again.
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So today you're going to learn about the use of sauna.
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You're going to learn about the use
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of other heat related tools for health and optimization,
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not just for growth hormone, but also metabolic health,
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for controlling cortisol, even to impact mental health
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And in order to do that,
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you need to understand a little bit about the mechanisms
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of how you heat up and how you cool down,
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where the cells and circuits are in the brain and body,
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how those cells and circuits work.
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I promised to make the description of that,
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which follows very clear,
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even if you don't have a background in biology.
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And once you have that in hand,
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along with the understanding you now have
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about the fact that you got a shell and a core,
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and you need to think about both the shell and the core,
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well, then you will be in the best possible position
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to use sauna or hot tub or other tools,
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even just a hot shower,
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as a powerful stimulus to optimize your biology.
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Now, the science of heat and heating,
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and cold and cooling for that matter,
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goes back well over a hundred years.
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In fact, it's kind of amusing to me
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that nowadays there's a kind of renewed interest
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in the use of heat and cold and the science of heat and cold
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because this was the first topic
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that I studied as an undergraduate.
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And in fact, I did my graduate thesis on thermal regulation.
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thermal regulation wasn't really considered
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one of the hot topics in neuroscience.
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People were more focused on things like memory
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and consciousness,
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and of course those topics are still of vital interest
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to many people in many laboratories.
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But thermal regulation was considered more,
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I think for the physiologists.
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Nowadays, not just on social media,
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not just in the landscape of biohackers and athletes,
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but in the landscape of mental health,
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and frankly in the general ethos around health optimization,
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people are really interested in heat and cold.
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And the reason they're so interested in heat and cold
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is that a lot of the science has been done
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both in animal models in mice and in humans,
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and translates immediately to protocols
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that anyone can use.
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Now, a brief warning now and another brief warning later,
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anytime you're talking about heating up your body,
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you need to be very cautious because unlike cooling down
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where you have a fairly broad range of cold temperatures
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that you can go into before it's damaging to tissue,
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well, you don't get to heat up the brain and body very much
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before you start getting into the realm of neuron damage.
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And neurons in the central nervous system,
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the brain and spinal cord,
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once they're damaged, they don't come back.
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So hyperthermia is a serious thing to avoid.
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Later, I'll talk about ways to rapidly protect
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against hyperthermia.
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But I do want to give everybody a cautionary note upfront.
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Obviously, if you're pregnant, nursing,
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if you're very sensitive to hot environments,
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you want to stay out of saunas and things of that sort.
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I'm sure there are exceptions to that.
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You definitely have to talk to your doctor
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if you're going to violate that rule.
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And for everybody, you want to approach
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any kind of tool related to heating very cautiously.
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You always have the opportunity
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to increase the temperature later.
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So proceed with caution, be smart about it.
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I don't just say that to protect me,
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I say that also to protect you.
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So now let's talk about what are the circuits for heating up?
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How does that happen?
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Many of you have probably experienced a fever.
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How does that happen?
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What happens when you go into a cold environment
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and you're shivering, but you put on a coat
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and then you feel warmer?
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What's really going on there?
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Well, there's a very basic circuit,
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meaning neurons that exist in the skin,
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in the brain and in the body
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that communicate with one another,
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that allow you to heat up if you need to
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and cool down if you need to.
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I'm going to throw a little bit of nomenclature,
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a few new words at you.
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You don't need to memorize these words except for one.
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Actually you need to memorize one acronym,
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but it's very easy.
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It's called the POA.
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If you remember POA,
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you'll be home free for the rest of the episode.
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But I know that there are some aficionados out there
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and people interested in getting
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a little bit deeper mechanism.
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And I do think it's important to understand this circuit
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because once you understand this circuit
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and the way it's structured,
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then you are going to be in a great position
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to use the tools related to heating.
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So here's how this circuit is structured.
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You have this shell, which is basically skin.
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And within the skin, you have neurons, nerve cells.
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Those nerve cells have channels or receptors on them.
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They're called trip channels.
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There are some other ones as well,
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which basically sense changes in heat.
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So if I were to put a hot object on your hand or your arm,
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if I were to put a hot object on your hand or arm
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and then remove that hot object,
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those neurons would respond to that.
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They would send electrical signals into your spinal cord.
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And that's where the next station of this circuit resides.
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In your spinal cord, you've got a little cluster of neurons
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that exists at the top part of your spinal cord
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called the dorsal horn.
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The name again doesn't matter.
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And those neurons specifically relay heat information
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up to another area of your brain.
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Now here's where we get into some fancy names.
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It's the lateral parabrachial area.
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You don't need to know lateral parabrachial area,
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but it's a relay station.
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The lateral parabrachial area sends electrical signals
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And I would like you to know POA.
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The POA stands for preoptic area.
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Neurons in the preoptic area
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basically reside over the roof of your mouth.
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These are neurons within the hypothalamus.
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And neurons in the preoptic area
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have the ability to send signals
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out to the rest of your brain and body
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to get you to heat up
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and actually to change your behavior so that you heat up.
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If neurons in the preoptic area receive an electrical signal
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through the circuit I just described
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that goes from skin to dorsal horn in the spinal cord
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to lateral parabrachial,
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they will start sending signals
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out to the organs of your body
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and the tissues of your body
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to get those organs and tissues to do things.
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And believe it or not,
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your POA, your preoptic area will actually change the way
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that you think and feel immediately.
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if something warm contacts your skin
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or something very hot contacts your skin,
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the preoptic area will send signals
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out to the endothelial cells,
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the blood vessels, both of the brain and body
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that get them to dilate, right?
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To essentially increase their volume
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and their surface area in order to cast off heat.
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You will also start sweating.
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That sweating response is initiated
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not by the hot day or the hot sun,
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but by the preoptic area neurons that send signals
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out to what's called the periphery of your body
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and other chemicals are released,
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things like acetylcholine that get you to sweat.
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And if you happen to be shivering,
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neurons in the preoptic area will make sure
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that you stop shivering.
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You're probably familiar with the feeling
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of being somewhat lethargic
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or spreading out your limbs on a hot day.
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Well, that is the result of neurons in your preoptic area
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impacting your musculature
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to get you to increase your surface area
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so you can sweat off or release more heat.
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So there are all these different mechanisms
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by which we dump heat.
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Some of those are purely physiological,
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below our conscious control, things like sweating,
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which you can't just make yourself sweat on demand.
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Maybe you can through a set of stressful thoughts,
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but you can't just make yourself sweat.
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That is autonomic, it's below your conscious control.
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Things like vasodilation,
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the dilation of your veins in particular
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and capillaries in particular, these sorts of things.
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And of course, there are these behavioral,
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somewhat voluntary aspects of dumping heat.
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And the lethargy, the kind of tiredness
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that we feel on a really hot day,
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that's also controlled by this circuit
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that I just described.
link |
In fact, I just got back from a visit
link |
to a very warm place.
link |
And it was remarkable to me
link |
how lethargic I felt in the afternoons.
link |
I just felt like a total slug.
link |
I just could not move or rally to do anything,
link |
except if I waited until the evening,
link |
even though it was later in the day,
link |
even though I hadn't napped,
link |
as the temperature in my environment cooled off,
link |
as my body temperature cooled off,
link |
I felt like I had more energy.
link |
I was actually waking up
link |
even though I had been awake for longer.
link |
So the relationship between temperature and lethargy
link |
is a very intimate one.
link |
If we're warm enough, we feel active
link |
and like we want to move around.
link |
If we're too warm, we feel like we need to stay put
link |
and spread out our limbs and dump heat.
link |
And that brings me to a quick and kind of fun point
link |
about how we dump heat versus how other animals dump heat.
link |
Many of you know, of course, that we dump heat by sweating.
link |
Other mechanisms as well, some of which I described,
link |
but that's our main way of dumping heat.
link |
Other animals like dogs don't have the capacity to sweat,
link |
at least not very much.
link |
So they pant, right, in order to dump heat.
link |
And still other animals like rodents,
link |
when they get too hot, they spit on their paws
link |
and they rub that spit on the surface of their body,
link |
which might sound kind of gross
link |
and probably will get you to think twice
link |
before petting any of those animals
link |
or holding any of those animals again,
link |
unless that's your thing.
link |
Now, one other key thing to understand
link |
about this circuit related to heat
link |
is that the preoptic area
link |
also can send electrical signals to the amygdala,
link |
a brain area that is often talked about
link |
in the context of fear,
link |
but is really just a brain area
link |
that can activate your sympathetic nervous system.
link |
The sympathetic nervous system
link |
is part of your autonomic nervous system
link |
and is the one associated with fight or flight
link |
or with the stress response,
link |
or even just the excited response, right?
link |
The sympathetic nervous system is also what gets activated
link |
when you're really excited about something.
link |
The preoptic area has the opportunity
link |
to trigger the activation of the amygdala.
link |
Now it doesn't do it every time, but it can.
link |
And it tends to do that
link |
when you are suddenly in an environment that feels too hot,
link |
that you feel is risky levels of hot.
link |
If you ever have gotten into a sauna
link |
that was very, very hot, maybe 210 degrees Fahrenheit,
link |
you sit there for a minute,
link |
you'll notice that your heart rate increases
link |
and there are reasons for that
link |
and we'll talk about some of the health benefits of that
link |
in a few minutes, but it's pretty uncomfortable.
link |
You may not feel like your skin is going to burn up,
link |
but you often will feel the impulse to get out,
link |
especially if you stay in there for a little while.
link |
That impulse is the consequence of this preoptic area
link |
communicating with your amygdala saying,
link |
hey, this environment is really hot
link |
and I'm trying to cool down and it's not really working.
link |
I'm dumping heat, but I'm not able to adjust
link |
the core of my body temperature
link |
in ways that are going to protect my neurons.
link |
And so it's a signal that you probably shouldn't stay
link |
in that environment too long.
link |
Now later we'll talk about the advantage
link |
of pushing yourself a little bit
link |
through some of these very hot environments
link |
provided you can do it safely,
link |
but the impulse to get yourself out
link |
of a very hot environment is the consequence
link |
of the POA communicating with your amygdala
link |
and the amygdala then in turn activating your adrenal glands
link |
which sit right above your kidneys,
link |
the release of adrenaline and this feeling of agitation
link |
like you want to move.
link |
Usually you want to move out
link |
of whatever hot environment you happen to be in.
link |
So now you know the circuit.
link |
Again, it's simple.
link |
It goes from skin to spinal cord,
link |
one brain area to another brain area.
link |
That's the key one in this discussion,
link |
which is the POA, the preoptic area.
link |
And the preoptic area can kick off a bunch
link |
of autonomic subconscious responses to heat,
link |
which make us attempt to get cooler,
link |
things like sweating, vasodilation, et cetera.
link |
And it can kick off behavioral responses,
link |
spreading out our limbs in an attempt
link |
to dump even more heat, feeling lethargic.
link |
So a lack of desire to run and move.
link |
And it also has the opportunity to kick off a mild
link |
or maybe not so mild panic response to get us
link |
out of that hot environment.
link |
If you can conceptualize that circuit,
link |
or if you can even just understand what I just said,
link |
even at a top contour level,
link |
you're going to be in a great position
link |
to understand the rest of the information
link |
and the tools that follow.
link |
Next, I'd like to talk about the use
link |
of deliberate heat exposure, including sauna,
link |
but other tools as well,
link |
as a way to understand how heat
link |
and heating changes our biology.
link |
So you're going to learn some mechanism
link |
and you're going to learn some tools.
link |
But first I'd like to just emphasize
link |
that the use of deliberate heat exposure
link |
can be a very powerful way to improve health and longevity.
link |
There's a wonderful study on this that was published in 2018
link |
that includes a lot of data from a lot of participants
link |
in a lot of different conditions.
link |
For instance, people that only did sauna once
link |
versus two to three times a week
link |
versus four to seven times a week and so on,
link |
and compares all those.
link |
The title of the study is sauna bathing
link |
is associated with reduced cardiovascular mortality
link |
and improves risk prediction in men and women,
link |
a prospective cohort study.
link |
This is one of several papers that clearly demonstrate
link |
that regular use of sauna
link |
or other forms of deliberate heat exposure
link |
can reduce mortality to cardiovascular events,
link |
but also to other events, things like stroke
link |
and other things that basically can kill us.
link |
What I like so much about this and the related studies
link |
and yes, I will provide a link to these in the show notes
link |
is that they involve a lot of participants.
link |
So for instance, in this particular paper,
link |
which was published in BMC medicine,
link |
they looked at a sample of 1,688 participants
link |
who had a mean age of 63,
link |
but there was a range of ages around 63
link |
and of whom 51.4% were women, the rest were men.
link |
So it's a pretty nicely varied study
link |
in terms of the populations that they looked at.
link |
And basically what they found was the more often
link |
that people do sauna, the better their health is
link |
and the lower the likelihood they will die
link |
from some sort of cardiovascular event.
link |
Now, what do we mean by sauna?
link |
We need to define some of the parameters around sauna
link |
and I promise to provide you some alternative ways
link |
to access some of the health benefits
link |
that were observed in this and related studies
link |
without the need to have a sauna
link |
because I do realize that a lot of people
link |
don't have access to sauna.
link |
First off, the temperature ranges that were used
link |
in this study and pretty much all the studies
link |
that I'm going to talk about unless I say otherwise
link |
are between 80 degrees Celsius,
link |
meaning 176 degrees Fahrenheit and 100 degrees Celsius,
link |
meaning 212 degrees Fahrenheit.
link |
So somewhere in that range,
link |
how hot should you make the sauna
link |
or the environment that you get into
link |
should you decide to use these tools?
link |
Well, that will depend on your tolerance for heat,
link |
how heat adapted you are.
link |
Yes, some people are better at sweating than others
link |
and over time, we all get better at sweating.
link |
Meaning if you go into the sauna more frequently,
link |
you become a better sweater.
link |
Not a sweater you wear, but the verb, sweater.
link |
You get better at sweating, at dumping heat
link |
through the loss of water.
link |
So it's going to depend.
link |
I recommend starting on the lower end
link |
of the temperature scale and if that's too hot for you,
link |
that you even lower the temperature further.
link |
Now, how long were people exposing themselves
link |
to these hot environments?
link |
Anywhere from five to 20 minutes per session.
link |
And as you'll soon learn,
link |
very brief periods of just five minutes of heat exposure
link |
can be a powerful stimulus if the heat exposure
link |
is significantly great enough for you, okay?
link |
20 minutes can also be beneficial,
link |
but 80 to 100 degrees Celsius,
link |
meaning 176 degrees Fahrenheit to 212 degrees Fahrenheit
link |
is the general range that this and most studies use.
link |
In this particular study, they compare the effects
link |
of people that did sauna once a week,
link |
two or three times per week or four to seven times per week.
link |
And what they saw was really remarkable.
link |
What they observed was that people who went into the sauna
link |
two or three times per week were 27% less likely
link |
to die of a cardiovascular event
link |
than people that went into the sauna just once a week.
link |
Again, at the temperature levels
link |
and the duration that I talked about earlier.
link |
And as you can imagine,
link |
the duration and the temperature levels were related.
link |
So if people went into very hot environments
link |
that were really uncomfortable for them,
link |
maybe they only went in for five minutes.
link |
Whereas if they were more comfortable and heat adapted
link |
in a given environment or their tolerance for heat
link |
was just simply higher for whatever reason,
link |
well, then they tended to stay in longer.
link |
We can take a sort of average of this five
link |
to 20 minute range.
link |
And today we're mainly going to talk about exposures
link |
between 10 and 20 minutes at temperatures between,
link |
again, 80 degrees and 100 degrees Celsius,
link |
176 degrees Fahrenheit or 212 degrees Fahrenheit.
link |
So these data point to the fact that going in the sauna
link |
two or three times per week is really beneficial
link |
and can lower mortality to cardiovascular events.
link |
And in fact, the benefits were even greater
link |
for people that were going into the sauna
link |
four to seven times per week.
link |
Those people were 50% less likely to die
link |
of a cardiovascular event compared to people
link |
that went into the sauna just once a week.
link |
So these are really impressive
link |
and frankly encouraging studies.
link |
Certainly they caught my eye and encouraged me
link |
to start using deliberate heat exposure on a regular basis.
link |
What's particularly nice about this study
link |
and the related study that again is linked in the show notes
link |
is that they looked at a number
link |
of potentially confounding variables,
link |
things like whether or not people smoked,
link |
things like whether or not people were overweight,
link |
whether or not they tended to exercise or not exercise,
link |
and they were able to separate out those variables.
link |
So the percentages that I described earlier,
link |
27% less likely to die of a cardiovascular event
link |
for those that went in the sauna two to three times a week
link |
and 50% less likely to die of a cardiovascular event
link |
for those that went into the sauna four times per week
link |
as compared to just once a week.
link |
Those effects really do seem to be the consequence
link |
of the sauna exposure and not some other effect
link |
that's correlated with sauna exposure,
link |
like going to the gym where people are working out
link |
seven times a week and then also happen
link |
to get into the sauna,
link |
or quitting smoking right about the same time
link |
they adopt a sauna protocol, these sorts of things.
link |
And now there have been additional analyses
link |
of the use of sauna for improving health,
link |
or I should say for offsetting mortality
link |
that have found that it's not just reductions
link |
in cardiovascular events,
link |
but so-called all cause mortality.
link |
This is kind of medical geek speak.
link |
We're saying, how likely are you or somebody to die
link |
from a cardiovascular event,
link |
but maybe also from some other event,
link |
some other health-related event,
link |
like cancer or something of that sort.
link |
And in every case, regular exposure to sauna,
link |
starting at about two or three times per week,
link |
all the way up to seven times per week,
link |
meaning statistically significant improvements in longevity
link |
in the sense that people are less likely to die
link |
of cardiovascular events and other things that kill us.
link |
So I and many other people who are interested,
link |
not just in our own health,
link |
but in educating about health-related tools
link |
to the general public, find this really exciting.
link |
But knowing what we know about how heat impacts our biology,
link |
it probably shouldn't surprise us
link |
that this sauna-type exposure or deliberate heat exposure
link |
has these incredible effects.
link |
So before we get into the biological mechanisms
link |
of how heat can have all these impressive health effects,
link |
I want to just talk about the use of sauna as a tool
link |
and emphasize that you don't have to use a sauna
link |
in order to get these benefits.
link |
It is simply a matter of making sure
link |
that your shell and your core heat up properly a bit,
link |
not too much, not too little, but that you heat those up.
link |
And no, you do not need to carry a thermometer around
link |
or place a thermometer into your core.
link |
You know, in laboratory studies and in humans,
link |
if you really want to know someone's core temperature,
link |
basically you try and put the thermal probe
link |
as close to the core as you can.
link |
So typically that's done rectally or a mouth thermometer
link |
or even up the nose.
link |
You don't need to do any of that, all right?
link |
This isn't a laboratory study.
link |
There are ways to create a hot environment
link |
such that you heat up your shell and your core safely
link |
without having to measure your core temperature all along.
link |
If you want to do that, be my guest,
link |
but I'm not going to provide a protocol.
link |
So the question is, how are you heating up your environment?
link |
And I realized that there are dry saunas,
link |
there are steam saunas, there are infrared saunas,
link |
there are hot tubs, and there are simply rooms
link |
that you crank up the heat, okay?
link |
There are also ways in which you can increase your shell
link |
and your core temperature by moving around a lot
link |
and doing that wearing a lot of clothing.
link |
There's nothing special about any one
link |
of these approaches or protocols.
link |
It's just so happens that sauna is one
link |
of the more convenient ways to do this.
link |
And certainly for the studies that I've talked about,
link |
not just the ones I referenced before,
link |
but all the studies that I researched
link |
looking at this episode,
link |
it makes sense why they would use sauna
link |
because it's very hard, for instance,
link |
to create conditions where you have five people go out
link |
jogging, wearing heavy sweaters and hats,
link |
wool hats on the middle of summer.
link |
It's very hard to set up those conditions
link |
in a way that's controlled for everybody,
link |
whereas it's pretty straightforward to have a sauna
link |
where you have one or several people just get
link |
into that one uniformly hot environment.
link |
That's a much easier study to run.
link |
So just to be clear, the temperature range is important.
link |
You want to get between 80 and 100 degrees Celsius.
link |
Now you know the conversion to Fahrenheit.
link |
You could, however, immerse yourself in a hot tub
link |
or hot water bath up to your neck.
link |
That's another way to approach it.
link |
If you didn't have access to either of those,
link |
you could also put on a hoodie or a wool hat and a hoodie,
link |
or you could do like the wrestlers do,
link |
and you could actually buy one of these plastic suits.
link |
They're literally called plastics that wrestlers
link |
or other athletes that wish to drop water weight will wear
link |
and then go jogging in that.
link |
All of those will increase your shell
link |
and your core body temperature, right?
link |
Especially if you do it on a hot day,
link |
but of course, be careful, hydrate and don't overheat,
link |
don't become excessively hyperthermic
link |
because you can get heat stroke and you can potentially die.
link |
But if you're going to use sauna,
link |
often I get the question, how hot should the sauna be?
link |
Well, now you know.
link |
How long should you be in there?
link |
Five to 20 minutes per session.
link |
Although I will talk in a minute about ways
link |
to optimize hormone output,
link |
in particular growth hormone output
link |
by doing four very brief sessions.
link |
So maybe not a continuous session.
link |
We'll get into that in a few minutes.
link |
And of course you have to ask yourself wet sauna, dry sauna.
link |
Use what you prefer.
link |
Many people ask me, well, what about infrared sauna?
link |
We have an entire episode all about the use of light
link |
and low level light therapy, including infrared light.
link |
It does have certain benefits for skin and other organs
link |
and tissues of the body if used properly.
link |
My understanding, or at least my assessment
link |
of most infrared saunas out there
link |
is that they don't get hot enough.
link |
They don't get up to that 80 to 100 degrees Celsius range.
link |
Some do, most don't.
link |
So what you end up with is a situation
link |
where you've got a red light,
link |
low level light therapy stimulus,
link |
and you've got a sauna that's not quite hot enough.
link |
And there are a lot of ideas and claims
link |
about how they work together
link |
in order to get you improved benefits.
link |
I personally am of the stance
link |
based on the literature that I've read
link |
that you want to get into those ranges
link |
of an 80 to 100 degrees Celsius
link |
before you start considering whether or not
link |
you're also going to include red light therapies, et cetera.
link |
So there's nothing special about red light sauna.
link |
It's really the temperature of the sauna
link |
that you happen to get into.
link |
So which tool, right?
link |
Which sauna, which stimulus?
link |
Do you run in wearing plastics and a hoodie and a wool hat?
link |
Do you get into a sauna?
link |
That's going to depend a lot on your circumstances,
link |
your budget, and what you have access to on a regular basis.
link |
This is a lot like our discussion about the use of cold.
link |
Most of the studies have looked at immersion in cold water
link |
up to the neck because that's a very controlled situation
link |
that you can do in a laboratory.
link |
They have not explored cold showers as much,
link |
so there's just less data
link |
or walking around in a cold environment.
link |
But we'll talk a little bit about those data
link |
because as you'll soon learn, when you talk about cold,
link |
you're actually talking about heating as well.
link |
So what kind of mechanisms are activated
link |
in your brain and body that allow
link |
for the various health benefits of sauna
link |
or other forms of deliberate heating?
link |
Well, we talked about reduced risk
link |
of cardiovascular event-related mortality
link |
and all-cause mortality.
link |
As you'll soon learn, there are also tremendous benefits
link |
in terms of increases in growth hormone,
link |
reductions in cortisol, et cetera.
link |
I will detail those.
link |
So what happens when you get into a hot environment?
link |
What are the mechanisms that allow
link |
for the various health effects of that?
link |
Well, your shell, your skin senses that,
link |
and through the circuit that I described earlier,
link |
activates neurons in the POA, the preoptic area,
link |
which in turn activates mechanisms
link |
in your autonomic nervous system like vasodilation.
link |
So blood flow increases, plasma volume
link |
of your blood increases, and stroke volume.
link |
The volume of blood that is mobilized
link |
with each beat of your heart also increases.
link |
And your heart rate increases to anywhere
link |
between 100 to 150 beats per minute.
link |
That general constellation of effects looks
link |
a lot like cardiovascular exercise.
link |
And in fact, for all intents and purposes,
link |
it really is cardiovascular exercise,
link |
except that there isn't the mobilization
link |
and the loading of joints and limbs and things of that sort.
link |
And of course, there are additional benefits
link |
of cardiovascular exercise that relate
link |
to impact on the ground, improvements in bone density,
link |
et cetera, et cetera.
link |
But basically your heart starts beating,
link |
more blood starts circulating,
link |
your vasculature changes shape literally
link |
to accommodate those increases in heart rate
link |
And you're basically getting a cardiovascular workout
link |
in that hot environment, even if you're just sitting down.
link |
Another set of positive effects related
link |
to being in these hot environments are hormone effects.
link |
Shifts in the output of hormones,
link |
both from your adrenals and possibly from the testes
link |
and ovaries, and even within the brain.
link |
One of the more striking examples of that comes
link |
from a study that was published in 2021.
link |
The title of the study is endocrine effects
link |
of repeated hot thermal stress
link |
and cold water immersion in young adult men.
link |
And indeed the study was in this case, just done on men.
link |
I'll just briefly describe the protocol they use.
link |
They had these men attend four sauna sessions
link |
of 12 minutes each.
link |
So again, well within that range of five to 20 minutes,
link |
12 minutes, the temperature of those saunas
link |
was 90 to 91 degrees Celsius.
link |
So I'll just quickly do the calculation,
link |
admittedly not in my head.
link |
That's 194 degrees Fahrenheit.
link |
And they did that four times.
link |
Afterwards, they had a six minute cool down break
link |
during which they did get into some cool water
link |
or cold water of about 10 degrees,
link |
which is 10 degrees Celsius is 50 degrees Fahrenheit.
link |
And then they measured hormones at various times
link |
throughout this study, before, during and after.
link |
They looked at testosterone, they looked at DHEA,
link |
which is in the androgen pathway.
link |
They looked at prolactin and they looked at cortisol.
link |
The significant effects of the protocol
link |
that I just described were on cortisol,
link |
a so-called stress hormone.
link |
So-called because when we are very stressed
link |
for long periods of time,
link |
cortisol levels tend to increase dramatically.
link |
But I should point out that a increase in cortisol each day
link |
right about the time of waking
link |
and specifically right about the time of waking
link |
is actually beneficial for our alertness and our energy.
link |
So having some increase in cortisol every 24 hours
link |
is a good thing provided it happens early in the day.
link |
Late day increases in cortisol
link |
are associated with depression.
link |
That's been shown by studies at Stanford and elsewhere.
link |
The major effect of this study is a significant decrease
link |
in cortisol output in these subjects.
link |
I think this is really interesting and important
link |
because many people suffer from acute,
link |
meaning immediate and long-term stress
link |
and are looking for ways to control their stress.
link |
Controlling your cortisol is tricky.
link |
In the episode on stress, I talked about supplements
link |
such as ashwagandha that can be used to limit cortisol,
link |
but you have to be careful not to use ashwagandha
link |
for extended periods of time,
link |
meaning for longer than two weeks,
link |
because you can get into other issues.
link |
I talk about breathwork protocols that can allow you
link |
to clamp or reduce the stress response in real time.
link |
Again, see that episode for those.
link |
But many people are overworked, they're overstressed.
link |
They're, for one reason or another,
link |
they're subjected to many, too many stressors
link |
or their level of stress resilience isn't high enough
link |
to keep their cortisol levels clamped at a healthy level.
link |
So the protocol I described of 12 minute exposures
link |
to 90 degree environment, that's again, 90 degrees Celsius,
link |
followed by a six minute cool down break in cool water,
link |
50 degrees or so, that's pretty cold.
link |
I can imagine that you could also just take a cool shower
link |
or a cold shower afterwards.
link |
That had a very significant effect on lowering cortisol.
link |
So there you have a tool, it's not a completely zero cost
link |
tool because you need to heat the water,
link |
you need to have access to hot and cold water,
link |
at least hot and cold contrast of some sort,
link |
but it's fairly minimal cost for most people,
link |
especially if you start getting creative
link |
about maybe taking a 12 minute jog,
link |
wearing a lot of clothing, if it's hot out,
link |
then getting into a cool shower,
link |
you might not get the same extreme or significant reduction
link |
in cortisol that was observed here
link |
with these very specific protocols,
link |
but it's likely that you would get
link |
a similar result overall.
link |
Now, I mentioned they did look at these other hormones
link |
and I'll just tell you that they did not see
link |
significant shifts in testosterone,
link |
prolactin, DHEA, et cetera, using this protocol.
link |
As you'll soon see, there are other sauna protocols
link |
that can impact those other hormones.
link |
So if you're seeking to use sauna to reduce stress,
link |
I think this is a very interesting
link |
and potentially useful research backed protocol.
link |
And again, we will provide a link to the paper
link |
if you'd like to read more about the data.
link |
So that is one set of biological effects on cortisol
link |
and the related protocol.
link |
What about some of the other benefits of sauna?
link |
Well, we'll talk about those,
link |
but I want to talk about those in the context
link |
of the underlying mechanisms,
link |
because if you understand those underlying mechanisms,
link |
you can really tailor your sauna protocols
link |
for your particular needs.
link |
One of the more dramatic and important effects
link |
of going into a hot environment for some period of time
link |
is the activation of so-called heat shock proteins or HSPs.
link |
Heat shock proteins are a protective mechanism
link |
in your brain and body to rescue proteins
link |
that would otherwise misfold.
link |
Now, what do I mean by this?
link |
Well, most of you are familiar with the fact
link |
that you have protein in the kitchen,
link |
like a steak or a piece of chicken or a piece of fish,
link |
and you heat it up, it changes its texture, right?
link |
Raw meat is different than cooked meat,
link |
to be quite blunt about it.
link |
Heat changes the quality of proteins,
link |
not just in terms of how they taste,
link |
but the way in which they are configured.
link |
It changes it right down at the molecular level.
link |
When your body goes through changes in temperature each day,
link |
and we'll talk about those changes,
link |
but in response to hot environments or cold environments,
link |
heat shock proteins are deployed to go and rescue
link |
and prevent the changes in proteins
link |
that would be detrimental to your health.
link |
So at least in the short term,
link |
activating heat shock proteins is a good thing.
link |
You don't want heat shock proteins to be activated
link |
for long periods of time,
link |
because that gets to be problematic for other reasons.
link |
But these heat shock proteins,
link |
of which there are many varieties,
link |
basically have the job of traveling in your brain and body
link |
and making sure that cells that contain proteins
link |
that are misfolding because they got heated up too much,
link |
And they also serve a protective mechanism,
link |
making sure that proteins within the cells
link |
of your brain and body don't fold in the wrong ways.
link |
Again, I'm describing this in very general terms,
link |
but it's well-established in animal models and in humans
link |
that sauna exposure of the sort that I described earlier
link |
activates these heat shock proteins.
link |
There's some interesting studies that were carried out
link |
in animal models that really nicely mechanistically support
link |
the role of heat shock proteins in some of the benefits
link |
of deliberate heat exposure.
link |
Some of these studies were done in flies,
link |
meaning Drosophila fruit flies,
link |
because they're a great model organism
link |
because you can delete genes or add genes easily.
link |
Other studies have been done in mice.
link |
And now there are also studies being carried out in humans.
link |
And I will talk about those.
link |
One of the more dramatic examples
link |
that's always touted in this field
link |
of deliberate heat exposure as it relates to longevity
link |
is that if they expose these flies, these fruit flies,
link |
to 70 minutes of a heat stimulus
link |
that obviously didn't kill them,
link |
but activated heat shock proteins,
link |
it could extend their life by 15%
link |
in a heat shock dependent way.
link |
Meaning if they made flies
link |
that didn't have these heat shock proteins,
link |
well, then they didn't see this extension in life.
link |
And this is one of the reasons to use model organisms.
link |
This is not an experiment that you could do in people.
link |
However, there have been interesting studies done in humans
link |
examining some of the downstream molecular pathways
link |
of deliberate heat exposure that point to the mechanisms
link |
by which deliberate heat exposure can help protect
link |
against different forms of mortality,
link |
improve health overall, and possibly,
link |
and I want to highlight possibly, possibly extend life.
link |
One such mechanism involves a genetic program
link |
involving a molecule called FOXO3.
link |
FOXO3 is a very interesting molecule
link |
because it's involved in DNA repair pathways.
link |
DNA repair is part of the process of remaining healthy.
link |
We'd all like to think that we're born
link |
and based on the genes we have,
link |
we are healthy, healthy, healthy,
link |
then eventually we age and then we die.
link |
But from the time we're born until the time we die,
link |
there's a constant repair of our proteins and our cells
link |
and a modification of the genes that are being expressed.
link |
You know, puberty being the most dramatic example, right?
link |
You see a kid before puberty and after puberty,
link |
he looks like a different kid, sounds like a different kid,
link |
thinks like a different kid,
link |
in fact, basically is a different human being, right?
link |
It's not just the hormones,
link |
it's that hormones themselves have the capacity
link |
to turn on and turn off certain genes,
link |
literally converting certain tissues
link |
and cells in the brain and body
link |
to do entirely different things.
link |
So it's not just the sprouting of new aspects
link |
of our biology, it's literally the conversion
link |
of different brain centers from one function to another.
link |
That's puberty and we'll do a whole episode about puberty.
link |
We actually did an episode on sexual development
link |
that talks a little bit about those mechanisms,
link |
but the point is that throughout our entire lifespan,
link |
genes are being turned on, genes are being turned off,
link |
genes are being turned on, genes are being turned off,
link |
and DNA, the stuff of genes gets damaged in that process.
link |
FOXO3 sits upstream in a pathway related to DNA repair
link |
and again, clearing of these senescent cells.
link |
Sauna exposure, in particular,
link |
sauna exposure two to three times
link |
or ideally four to seven times per week
link |
in that 80 to 100 degree Celsius range
link |
has been shown to upregulate levels of FOXO3.
link |
FOXO3 in turn upregulates pathways related to DNA repair
link |
and clearing out of these senescent or dead cells,
link |
which is known to be important for various aspects
link |
of maintaining cognition
link |
and other aspects of maintaining health.
link |
So these are the likely biological mechanisms
link |
for the improvements in lifespan
link |
or I rather, I should say,
link |
these are the biological mechanisms
link |
that apparently offset some of the cardiovascular risk
link |
and other forms of mortality that were described earlier.
link |
One especially interesting thing about FOXO3,
link |
there are individuals out there
link |
that have either additional copies of FOXO3
link |
or who have versions of FOXO3 that are hyperactive,
link |
Those people tend to be 2.7 times more likely
link |
to live to 100 years of age or longer.
link |
So these are people that were just naturally,
link |
and fortunately for them,
link |
endowed with more FOXO3,
link |
more clearance of senescent cells,
link |
more DNA repair, et cetera.
link |
For the rest of us, at least to my knowledge,
link |
I don't have one of these
link |
health-promoting FOXO3 mutations.
link |
Remember, mutations can be beneficial
link |
or they can be detrimental.
link |
This, if your goal is to live longer,
link |
is a beneficial mutation.
link |
Well, if you don't have these FOXO3 mutations
link |
that allow you to be a centenarian
link |
at 2.7 times higher likelihood than other people,
link |
deliberate heat exposure is one way
link |
that you can increase FOXO3 activity.
link |
At this point in time,
link |
meaning when looking at the research out there,
link |
it isn't clear what the optimal SONNA protocol
link |
is going to be specifically to increase FOXO3,
link |
and that's probably because there isn't one.
link |
There is no SONNA protocol designed
link |
specifically to reduce cortisol
link |
or specifically to increase FOXO3
link |
or specifically to activate heat shock proteins.
link |
Any deliberate heat exposure is likely
link |
to impact all of those mechanisms.
link |
Again, I encourage you to use this guide
link |
of 80 to 100 degrees Celsius
link |
as your kind of bookends for what you can tolerate
link |
and where you want to start and eventually transition to
link |
in terms of deliberate heat exposure.
link |
And I would encourage you to use
link |
that five to 20 minutes per session
link |
for the SONNA as your rough guide
link |
of how long to remain in the SONNA.
link |
Now, there was a study published just this last year
link |
that was mainly focused on deliberate cold exposure.
link |
I detailed this quite extensively in the episode on cold.
link |
This is the beautiful work of Susanna Soberg.
link |
And that study looked at deliberate cold exposure,
link |
but also SONNA exposure.
link |
And that study found that 57,
link |
yes, 57 minutes per week of SONNA exposure
link |
in conjunction with 11 minutes per week total
link |
of deliberate cold exposure was the threshold
link |
for getting improvements in metabolism
link |
and increases in brown fat,
link |
this very active fat tissue
link |
that improves mitochondrial function and thermogenesis,
link |
meaning heating of the body.
link |
We'll talk more about the brown fat later.
link |
Why do I mention this?
link |
Well, for those of you that are interested
link |
in increasing metabolism,
link |
it does seem to be most beneficial
link |
to do that 11 minutes per week of cold exposure.
link |
Again, divided up across two or more sessions.
link |
So it's not 11 minutes all at once, but shorter sessions.
link |
And to get 57 minutes minimum per week of SONNA exposure,
link |
again, in the temperature ranges
link |
that I've talked about here.
link |
And again, it's not 57 minutes in the SONNA all at once.
link |
That's 57 minutes total per week as the minimum threshold.
link |
So you might divide that into three sessions of 20 minutes.
link |
And again, I don't think 57 is the magic number.
link |
It could be 60, it could be 64, it probably could be 55.
link |
Remember your biological systems
link |
are not counting things off minute by minute,
link |
second by second, at least not in most cases.
link |
So for those of you that are interested
link |
in improving metabolism, check out the episode on cold,
link |
or just take the SOBERG protocol as I call it,
link |
which is 11 minutes total per week
link |
of uncomfortably cold, but safe cold exposure.
link |
So uncomfortably cold means you really,
link |
really want to get out of the shower or the ice bath
link |
or whatever environment, but you can stay in.
link |
11 minutes total per week divided across a couple of sessions
link |
and then 57 minutes per week or so
link |
of deliberate heat exposure.
link |
Again, uncomfortably, but uncomfortably hot, excuse me,
link |
but safe to stay in,
link |
probably divided up across three or more sessions.
link |
Okay, so we've talked about the use of SONNA
link |
to decrease cortisol.
link |
We've talked about the use of SONNA
link |
to increase heat shock proteins.
link |
We've talked about the use of SONNA to increase FOXO3.
link |
Now I'd like to talk about the use of SONNA
link |
to increase growth hormone.
link |
Growth hormone is a hormone that we all naturally secrete
link |
from our pituitary,
link |
which also resides near the roof of our mouth.
link |
The signal for the pituitary to release growth hormone
link |
arrives from neurons that exist in the hypothalamus.
link |
So growth hormone releasing hormones,
link |
believe it or not, that's what they're called,
link |
stimulate the release of growth hormone
link |
from the anterior pituitary gland
link |
into the general circulation.
link |
And then growth hormone impacts metabolism
link |
and growth of cells and tissues of the body.
link |
It is responsible for tissue repair as well.
link |
And the growth spurt that everyone experiences
link |
during puberty is the consequence of growth hormone.
link |
What I'm about to describe is a study
link |
that found dramatic, really dramatic, I should say,
link |
increases in growth hormone.
link |
But I also want to emphasize
link |
that these increases in growth hormone
link |
were not of the sort that are observed in puberty
link |
or in infants becoming adolescents
link |
or adolescents growing into teenagers.
link |
Those levels of growth hormone
link |
that are associated with those massive transformations,
link |
excuse me, of body morphology, of shape,
link |
are far greater than the sorts that I'm talking about here.
link |
And yet, as all of us age,
link |
when we go from adolescence to our teenage years
link |
and then into young adulthood,
link |
but then starting in our early 30s or so,
link |
the amount of growth hormone that we secrete
link |
is greatly diminished.
link |
Normally, we would release growth hormone every night
link |
after we go to sleep,
link |
in particular in the early part of the night
link |
when our sleep is comprised mostly of slow wave sleep.
link |
As we age, less growth hormone is released
link |
during that slow wave sleep.
link |
There are various things
link |
that can promote the release of growth hormone,
link |
and we will talk about
link |
some of those other things in a moment.
link |
Things like low blood sugar, it turns out,
link |
is a stimulus for growth hormone release.
link |
And I don't mean hypoglycemia of the sort
link |
that makes you dizzy and want to pass out, that's bad.
link |
I mean, not having high levels of glucose
link |
and insulin in your bloodstream.
link |
This is one of the reasons
link |
why many people are drawn to intermittent fasting
link |
or even prolonged fasting.
link |
It's because of the reported increases in growth hormone.
link |
I'll touch on those briefly,
link |
but if you want to learn more about those
link |
and what their real impact is
link |
and the extent of growth hormone,
link |
check out the episode I did on fasting.
link |
You can find that at hubermanlab.com.
link |
Certain forms of exercise have also been shown
link |
to stimulate growth hormone release.
link |
And in a few moments,
link |
I'll talk about how exercise and fasting can be combined
link |
or how heat can be combined with exercise
link |
or certain patterns of food intake
link |
to further increase growth hormone.
link |
But before I do that, I want to review some of the data
link |
and one study in particular that discovered
link |
certain forms of deliberate heat exposure using sauna
link |
can stimulate very large increases in growth hormone output,
link |
which for people in their 30s, 40s and beyond
link |
could be very useful and may also be useful
link |
for people who are just trying to stimulate
link |
the release of more growth hormone in order to,
link |
for instance, recover from exercise or stimulate fat loss
link |
or muscle growth or repair of a particular injury.
link |
The title of this paper is endocrine effects
link |
of repeated sauna bathing.
link |
And this is a paper that was published in 1986,
link |
which is some years ago,
link |
but nonetheless serves as a basis
link |
for a lot of other studies that followed.
link |
So let me describe what they did in the study.
link |
They used an 80 degree Celsius environment.
link |
So that's 176 degrees Fahrenheit.
link |
And they had subjects do this sauna for 30 minutes,
link |
four times per day.
link |
So that's two hours total in one day,
link |
30 minutes in the sauna, a period of cool down rest,
link |
30 minutes in the sauna again, cool down rest,
link |
a third and a fourth time, okay?
link |
So two hours total in this 80 degree Celsius environment.
link |
but what they observed was really quite significant.
link |
So they had subjects do this protocol
link |
and I should mention they had both male
link |
and female subjects in the study.
link |
And the entire study lasted a week.
link |
They did this two hours of sauna exposure on day one,
link |
day three and day seven of that week.
link |
And they measured a lot of different hormones,
link |
cortisol, thyroid stimulating hormone,
link |
thyroid hormone itself, luteinizing hormone
link |
and follicle stimulating hormone,
link |
which are hormones that essentially drive
link |
the production of other hormones.
link |
We won't get into that too deeply,
link |
but if you'd like to learn about FSH,
link |
follicle stimulating hormone and luteinizing hormone,
link |
please see the episode on optimizing testosterone
link |
and estrogen at hubermanlab.com.
link |
They looked at prolactin and they looked at growth hormone.
link |
I'll just cut to the chase and tell you
link |
the effects on growth hormone.
link |
In subjects that did this two hour a day,
link |
80 degree Celsius protocol,
link |
experienced 16 fold increases in growth hormone.
link |
So they measured growth hormone before the sauna
link |
and after the sauna and growth hormone levels
link |
went up 16 fold, which is obviously an enormous
link |
and it turns out statistically significant effect.
link |
Now, one important caveat here.
link |
Remember earlier when I talked about people who did sauna
link |
once a week versus two to three times a week
link |
versus four to seven times a week.
link |
And the more often people did sauna,
link |
the less likely they were to die of cardiovascular events
link |
or other things of that sort.
link |
Well, in this case, the effects of sauna exposure
link |
on growth hormone actually went down
link |
the more often that people
link |
did this deliberate heat exposure.
link |
So as I mentioned, they did this two hour a day
link |
dividing the 30 minute sessions protocol on day one,
link |
day three and day seven of a week.
link |
And what they found was on day one,
link |
there was a 16 fold increase in growth hormone.
link |
On day three however,
link |
there was still a significant effect on growth hormone
link |
as compared to before sauna,
link |
but that effect was basically cut by two thirds.
link |
So now instead of getting a 16 fold increase,
link |
it was more like a three or four fold increase,
link |
which is still a huge increase,
link |
but not as great as the increase observed on day one.
link |
And then on day seven, there tended to be a two,
link |
maybe a three fold increase,
link |
but not as great as the one observed on day one.
link |
What does this mean and why does this happen?
link |
Well, the reason this happens is because heat,
link |
just like cold is a shock or a stressor to the system.
link |
In the context of cold,
link |
if you get into a very cold ice bath, for instance,
link |
a five degree ice bath, even for 20 seconds,
link |
it's known to increase norepinephrine 200%.
link |
It can double the amount of norepinephrine
link |
that you suddenly release into your brain and body,
link |
which actually can have some positive effects.
link |
I'll talk about those in a little bit.
link |
But if you were to do that every day,
link |
you become cold adapted.
link |
This circuit that compares the shell and core of your body
link |
would adjust in ways that it could either predict
link |
that cold stimulus or more likely to create
link |
some thermogenic mechanisms in preparation
link |
for that cold exposure.
link |
This is why, for instance,
link |
people that use deliberate cold exposure
link |
to try and increase lipolysis, the burning of fat,
link |
oftentimes will get results for a while,
link |
but then if they're doing it a lot, a lot,
link |
they stop getting those effects.
link |
I talk a lot about avoiding cold adaptation
link |
if that's your goal in the episode on cold,
link |
but similar mechanisms are at play here.
link |
So we have to imagine that when these subjects
link |
got into the sauna on day one,
link |
whatever pathways went from measurement of temperature
link |
at the shell to changes in temperature at the core
link |
led to these big increases in growth hormone,
link |
which is basically a way of just describing the result
link |
I already told you before.
link |
But the fact that that result diminished over time
link |
either means that the circuit was not as efficient
link |
in communicating that shift in temperature
link |
or that that shift in temperature was of less impact
link |
because the downstream effectors
link |
were not engaged to the same extent
link |
because it wasn't as much of a shock.
link |
And I think the latter explanation is far more likely.
link |
This is very much akin to weight training
link |
or cardiovascular exercise,
link |
where if you run up a hill very fast, for instance,
link |
and your lungs are burning
link |
and you're heaving and breathing hard,
link |
on the first day, that's a very painful thing.
link |
But if you do it every day or every other day,
link |
provide you allow yourself to recover,
link |
pretty soon you're running up that hill
link |
and you're not breathing as hard.
link |
There isn't much burning in your muscles,
link |
et cetera, et cetera.
link |
So one of the key things to understand
link |
about the use of deliberate heat exposure
link |
is if you're going to use it in order to try
link |
and trigger massive increases in growth hormone,
link |
you're going to need to be careful
link |
about not doing it more than let's say once a week.
link |
Now I'm extrapolating from this study,
link |
maybe once every 10 days would be even better.
link |
But if you start getting heat adapted,
link |
it's very unlikely that you're going to get
link |
these massive increases in growth hormone.
link |
So I don't mean to be discouraging
link |
of using deliberate heat exposure
link |
to access growth hormone increases,
link |
but if that's your specific goal or your main goal,
link |
then I think it's reasonable to say
link |
that you don't want to do deliberate heat exposure,
link |
at least not of the sort that I described here,
link |
more than once a week, or maybe even once every 10 days.
link |
And that you would want to time that
link |
to other events in your life,
link |
maybe hard workouts,
link |
or if you're trying to push through a fat loss barrier,
link |
or simply in order to access growth hormone at peak levels,
link |
maybe three times per month or four times per month.
link |
If you start doing deliberate heat exposure more often,
link |
you'll still get increases in growth hormone,
link |
but they are not going to be nearly as large
link |
as the increases in growth hormone
link |
that you're going to experience
link |
if you shock your system with deliberate heat exposure
link |
every once in a while.
link |
An important way to frame this
link |
is actually in the context of cold.
link |
And while you might say, wait,
link |
this is an episode on heat and heating, not cold.
link |
You really can't have a conversation about heat and heating
link |
without talking about cold,
link |
because as I mentioned earlier,
link |
if you cool the outside of your body, the shell,
link |
you're actually heating up your body.
link |
In fact, the circuits that control heating of the body
link |
and that control cooling of the body,
link |
for instance, the activation of things like shiver
link |
or fat loss in response to cold and shiver,
link |
those are also controlled by the preoptic area
link |
of the hypothalamus.
link |
So we can take a step back and start to think about
link |
what it would take to design the optimal protocol
link |
for deliberate heat exposure by looking at cold.
link |
And here's what I mean.
link |
There have been beautiful studies showing
link |
that if people get into a very cold body of water,
link |
four degrees Celsius for 20 seconds,
link |
as I mentioned earlier,
link |
that will cause a 200 to 300% increase in norepinephrine.
link |
Norepinephrine is also called noradrenaline
link |
and norepinephrine and other so-called catecholamines
link |
like dopamine increase dramatically
link |
in this very brief cold water exposure.
link |
And those increases in norepinephrine and dopamine
link |
are known to have long lasting effects
link |
that generally to improvements in mood, focus and alertness.
link |
They're pretty significant.
link |
However, they aren't significant enough
link |
to increase metabolism to a very high degree.
link |
Whereas other studies have shown that if people go outside
link |
in 16 degrees Celsius weather with a proper amount,
link |
but a fairly minimum amount of clothing,
link |
you can experience even greater increases in norepinephrine.
link |
But the time that's required
link |
in order to experience those increases
link |
is six hours at, for instance, 16 degrees Celsius.
link |
So if you have six hours a day to be out there in the cold,
link |
or if you're going to turn the air conditioning on
link |
in an environment, make it very, very cold, fine.
link |
But basically what I'm describing
link |
is that you can sort of bookend the parameters
link |
You can use a very brief exposure to cold or to heat
link |
in order to stimulate heat shock proteins,
link |
growth hormone, et cetera.
link |
Or you can use longer exposure
link |
in less intense versions of heat and cold.
link |
You really have to find what's going to work for you
link |
and what you can do safely.
link |
And if you're confused about where to start,
link |
please use the parameters that I described earlier.
link |
First of all, check with your doctor as always,
link |
make sure that you're somebody
link |
who can do deliberate cold or heat exposure safely.
link |
But that 80 to 100 degrees Celsius,
link |
meaning 176 degrees Fahrenheit to 212 degrees Fahrenheit
link |
I keep repeating over and over
link |
because I know somebody is going to ask
link |
even though I repeat it over and over, which is fine.
link |
I'm delighted to keep saying it
link |
and to respond if someone asks again.
link |
Well, those parameters are going to kind of bookend
link |
what you should do in terms of the intensity
link |
of the heat stimulus.
link |
Well, we heard earlier, five to 20 minutes.
link |
Why not start with five and then ramp it up to 10 or 15?
link |
And then if you're feeling really bold
link |
and you really want to crank out growth hormone,
link |
well then you could do that 30 minute,
link |
four times in one day stimulus every once in a while.
link |
So you have to really figure out
link |
what you're using heat exposure for.
link |
This is one of the reasons why when people say,
link |
is it better to get in a wet sauna or dry sauna?
link |
What's the optimal temperature?
link |
Is it better to take a hot shower or a hot bath
link |
To be completely honest,
link |
it depends on what you're going to be able to do regularly,
link |
whether or not you want to do it regularly
link |
and what your specific goals are.
link |
So the purpose of this episode is really to arm you
link |
with the underlying mechanisms
link |
and to arm you with the general parameters
link |
that are going to allow you to access the results
link |
that you're seeking.
link |
For what it's worth, I personally use a protocol
link |
and I've been using a protocol for a long time
link |
that involves trying, meaning I accomplish this most weeks,
link |
not all, trying to get into a sauna
link |
for three 20 minute sessions every week.
link |
I use a dry sauna, so it's not a steam room.
link |
If I don't have access to it,
link |
I might take a hot bath or something of that sort.
link |
But in general, I just stick to doing the sauna
link |
three times a week.
link |
And I generally will do that either after a workout,
link |
either a cardiovascular workout or a weight workout,
link |
or I'll do it later in the evening.
link |
Why later in the evening?
link |
Well, it has to do with the circadian shifts in temperature
link |
that we all experience.
link |
Talked a lot about this in the circadian episodes
link |
and the episodes related to sleep,
link |
but in a nutshell, here's how it works.
link |
Every early morning,
link |
about two hours before your typical wake-up time,
link |
your body temperature is at its all time lowest.
link |
Okay, we call that your temperature minimum.
link |
Right about waking, your body temperature increases.
link |
In fact, an increase in body temperature
link |
is part of the reason you wake up at all,
link |
unless of course you're setting an alarm.
link |
Increases in body temperature are going to be
link |
one of the major things that wakes up your brain and body.
link |
Body temperature will tend to continue
link |
to increase through the morning.
link |
You'll get that increase in cortisol,
link |
that's a healthy increase in cortisol.
link |
Body temperature will increase into the afternoon
link |
and then will start to drop in the later afternoon.
link |
This general contour can be shifted
link |
by whether or not you exercise,
link |
because of the so-called thermogenic effects of food.
link |
That is every time you eat,
link |
there's a slight increase in body temperature and metabolism,
link |
but it's not really that significant
link |
to throw off this general contour and rhythm.
link |
But toward the afternoon, around four or five o'clock,
link |
most days, depending on time of year,
link |
your body temperature will peak
link |
and then it will start to drop.
link |
And as your body temperature drops by one to three degrees,
link |
and here I'm referring to your core body temperature,
link |
not your shell body temperature,
link |
you will start to get sleepy
link |
and to transition into sleep
link |
and to maintain sleep throughout the night,
link |
your body temperature will remain low
link |
until you hit that temperature minimum
link |
and then it'll start to come up again, okay?
link |
What that means is that when you decide to do sauna
link |
or cold exposure for that matter is going to be important.
link |
Well, as I mentioned earlier,
link |
if you were to make the surface of your body cold,
link |
at least in the immediate period after that,
link |
your body temperature will increase.
link |
So for those of you that are challenged
link |
in getting to sleep and are still working on your sleep,
link |
remember, sleep is the foundation
link |
of all mental and physical health and optimal performance.
link |
You should try to get really quality sleep
link |
of sufficient duration at least 80% of nights.
link |
That should be an ongoing goal throughout your lifespan
link |
for a huge number of reasons.
link |
Watch the master sleep episode
link |
if you'd like to hear more of those reasons
link |
and the mechanisms to make sure that you do that.
link |
But in any event, cold exposure late in the evening
link |
will start to increase your body temperature again.
link |
And that can make it hard for some people to fall asleep.
link |
Now, if you're very, very tired
link |
because you've been working hard or training hard
link |
or both throughout the day,
link |
might not throw off your sleep so much.
link |
I've gone through bouts where I'm just so, so busy
link |
from morning till night
link |
that the only time I can get into the ice bath
link |
or the cold shower is late in the evening
link |
and I have no trouble sleeping after that.
link |
However, if you have trouble sleeping,
link |
I would recommend doing the cold exposure early in the day
link |
to match that natural heating,
link |
that natural increase in body temperature
link |
that occurs across the 24 hour so-called circadian rhythm.
link |
Similarly, if you're going to use deliberate heat exposure,
link |
you'd be wise to do that later in the day.
link |
You'd be wise to do it later in the day
link |
because when you get into a warm environment,
link |
sure, the surface of your body, the shell heats up,
link |
the core of your body heats up,
link |
but then it also activates cooling mechanisms
link |
through the preoptic area.
link |
And when you get out of that hot environment,
link |
sauna or otherwise,
link |
your body will continue to cool down.
link |
And so many people find that if they do sauna
link |
in the later half of the day or even just before sleep
link |
and then take a warmish shower afterwards,
link |
then they find it easier to fall asleep.
link |
And that makes sense
link |
because their body temperature is dropping.
link |
And in fact, if your goal is to really promote
link |
the maximum amount of growth hormone release,
link |
that's also going to be the best time of day to do it,
link |
especially if you haven't eaten
link |
in the two hours before sleep, okay?
link |
So if you're really going for growth hormone release,
link |
you're really trying to optimize sleep
link |
and the two things are actually linked
link |
because of the release of growth hormone
link |
that happens from the pituitary in the early night's sleep,
link |
well, then you would be wise to do your sauna
link |
maybe once or maybe twice a week in the evening
link |
or at nighttime than taking a warm or cool shower
link |
just briefly, just enough to kind of rinse off all the sweat
link |
from the sauna and then get ready for sleep.
link |
And to do that, not necessarily fasted,
link |
but to try and keep your levels of glucose and insulin
link |
somewhat low in your bloodstream.
link |
The reason I say that is that having elevated blood glucose
link |
and or insulin tends to blunt
link |
or reduce growth hormone release.
link |
And that's true for any number of different stimuli,
link |
including exercise and including sauna.
link |
So there's a really nice study on this
link |
that I can point you to is this study
link |
that was published in the journal Stress,
link |
literally that's the name of the journal.
link |
I love it when journals have these names like pain
link |
or stress, I find that somewhat amusing for reasons
link |
that escape me, but nonetheless, amuse me.
link |
The title of this study is growth hormone response
link |
to different consecutive stress stimuli in healthy men.
link |
Is there any difference?
link |
And I don't want to go into all the details of the study
link |
because it's pretty extensive and complicated,
link |
but basically what they did is that they had people do sauna
link |
and then gave them a drug or a condition of having low,
link |
not dangerously low, but low blood sugar,
link |
or they had them in a condition where they had
link |
low blood sugar and then did sauna,
link |
or they had them do an exercise protocol
link |
that led them to increase growth hormone
link |
and then had them do low blood sugar,
link |
basically mixing and matching the various stimuli
link |
that could increase growth hormone.
link |
And what they found was very straightforward.
link |
What they found was that doing sauna once
link |
and then waiting some period of time,
link |
and then later that day doing sauna again,
link |
they didn't see the same increase
link |
in growth hormone both times.
link |
First, they got a big increase in growth hormone
link |
and then less if they did sauna again.
link |
If they had people do exercise and then sauna,
link |
what they found was exercise could stimulate growth hormone,
link |
but then following it with sauna did not allow you
link |
to get twice as much growth hormone.
link |
In general, anytime you release growth hormone,
link |
you reduce the likelihood that you're going to release
link |
growth hormone again later that day.
link |
And this partially explains that earlier study
link |
where if people did this growth hormone promoting protocol
link |
on day one, but then on day three,
link |
they didn't see quite as big an effect,
link |
and on day seven, they didn't see quite as big an effect.
link |
All it basically boils down to is that
link |
if you really want to crank out the most amount
link |
of growth hormone in response to sauna,
link |
do it fasted or at least not having ingested any food
link |
in the two or three hours before.
link |
You don't have to be deep into a fast.
link |
And the whole notion of what breaks a fast
link |
is kind of an interesting conversation
link |
because it's contextual, right?
link |
Will a sip of coffee break your fast?
link |
Well, maybe, probably not.
link |
Will one grain of sugar break your fast?
link |
Will an entire candy bar break your fast?
link |
Yes, it has to do with where your blood glucose is
link |
when you ingest that particular food item,
link |
not so much what that food item is per se.
link |
But the bottom line here is if you want to crank out
link |
the most amount of growth hormone,
link |
wait a couple of hours after eating
link |
before getting into the sauna,
link |
or maybe do it before dinner and then prepare dinner,
link |
do the sauna before dinner that is,
link |
then prepare dinner, then eat dinner,
link |
and then make sure that you wait a few hours
link |
before going to sleep.
link |
You're going to have to arrange your schedule accordingly.
link |
I know most people can't arrange their schedule perfectly
link |
just to get growth hormone increases,
link |
nor do I think people should approach
link |
health protocols that way.
link |
I think for 90% of people, 90% of the time,
link |
just getting into the sauna once or twice
link |
or three times a week is going to be beneficial
link |
for the number of reasons that I described earlier.
link |
And you don't want to obsess too much
link |
about the exact conditions you need
link |
in order to get the greatest effect
link |
out of that sauna treatment.
link |
These are just some additional tweaks
link |
related to food intake and low-level hypoglycemia
link |
and exercise that if you wanted to leverage, you could.
link |
So if decreases in body temperature
link |
tend to aid the transition to sleep,
link |
and getting out of a hot sauna
link |
tends to promote decreases in body temperature,
link |
it makes sense why you would want to put your sauna exposure
link |
or other deliberate heat exposure
link |
in the second half of your day
link |
and maybe even right before sleep.
link |
Now, regardless of what time of day you do sauna
link |
or how frequently you do it,
link |
you're going to want to hydrate after going in the sauna.
link |
When you go in the sauna, you lose water,
link |
and when you lose water, you need to replace it.
link |
Well, you need water for all your cells,
link |
but you also need electrolytes.
link |
So make sure that you're replacing the water
link |
that you lose in the sauna.
link |
Now, there's no exact formula of how much water to drink
link |
and whether or not you need electrolytes
link |
in that water or not.
link |
It's going to depend on how much you sweat,
link |
meaning how heat adapted you are.
link |
It's going to depend on how much salt you tend to excrete
link |
in your sweat, huge amount of variation.
link |
But in general, one way to approach this
link |
would be to make sure that you drink
link |
at least 16 ounces of water for every 10 minutes
link |
that you happen to be in the sauna.
link |
You could do that before and during and after,
link |
you could do it during and after, or you could do it after.
link |
Now, there are other reasons to do deliberate heat exposure
link |
that have nothing to do with cardiovascular effects,
link |
nothing to do with growth hormone or anything of that sort,
link |
but rather have to do with improvements
link |
in mood and mental health.
link |
In fact, the data related to sauna
link |
and other forms of deliberate heat exposure improving mood
link |
are very impressive, both at the mechanistic level
link |
and in terms of the long-term consequences
link |
that people experience.
link |
First of all, we need to ask,
link |
how is it that deliberate heat exposure
link |
can improve our mood and wellbeing?
link |
Well, it turns out that it improves mood and wellbeing,
link |
but it also improves our capacity to feel good
link |
in response to things
link |
that would ordinarily make us feel somewhat good.
link |
Now, this is not a situation
link |
where you're going to be walking around,
link |
grinning ear to ear in response to nothing at all,
link |
simply because you went in a sauna.
link |
What I'm talking about is the upregulation of pathways,
link |
meaning chemical pathways in your brain and body
link |
that allow you to experience pleasure in all its fullness.
link |
So here's how this whole deliberate heat exposure,
link |
sauna, mood thing works.
link |
Many of you have probably heard of endorphins.
link |
Endorphins are a category of molecules
link |
that are made naturally in your brain and body,
link |
and that are released in response to different forms
link |
That's right, in response to stressors.
link |
So if ever you've gone out on a long run,
link |
and at some point in that run,
link |
you feel like you're aching and your joints hurt,
link |
or maybe you have shin splints,
link |
and you push through that,
link |
part of the reason that you experience
link |
a lack of pain at some point, usually,
link |
or you experience a euphoria during or after that exercise
link |
is the exercise-induced effects on endorphin release,
link |
or rather, to be more specific,
link |
I should say the exercise-induced consequences
link |
on the stress system,
link |
which in turn trigger the release of endorphin.
link |
In other words, when we experience short-term
link |
or acute stress, the endorphin system is activated.
link |
Now, the endorphin system is not just about feeling good,
link |
believe it or not, it's also about feeling bad.
link |
And there are two general categories of endorphins.
link |
The first are the ones that you normally hear about,
link |
endorphins, things that bind, for instance,
link |
to receptors like the mu opioid receptor.
link |
Opioids are not just prescribed compounds
link |
or, unfortunately, drugs of abuse, which they are, right?
link |
We have this opioid crisis in the United States
link |
and elsewhere, which is a very serious and tragic thing,
link |
but we make endogenous opioids.
link |
We make endorphins that naturally act as pain relievers
link |
and that make us feel mildly euphoric.
link |
We also make endorphins such as dynorphin,
link |
that's D-Y-N-O-R-P-H-I-N, dynorphin,
link |
that actually make us feel worse in response to stressors.
link |
When we get into a hot sauna
link |
or a hot environment of any kind,
link |
dynorphins are liberated in the brain and body.
link |
And I should mention that dynorphins are made
link |
by many neurons in many different areas of the brain.
link |
So you might think, well, why would I want that?
link |
Why would I want to release dynorphin into my brain and body?
link |
Well, first of all, when you get into an uncomfortably
link |
hot situation, uncomfortably hot scenario,
link |
oh gosh, this is sounding terrible,
link |
in a deliberately hot environment
link |
that you are using to try and trigger
link |
some sort of biological or psychological benefit,
link |
I should say, the discomfort that you feel,
link |
the desire to get out of that environment
link |
is in part the consequence of the release of dynorphin.
link |
It's also the consequence of the activation
link |
of that sympathetic nervous system.
link |
Remember, the preoptic area can communicate
link |
with the amygdala and trigger that kind of fight
link |
or flight mode, I want to get out of the sauna,
link |
this is really, really hot.
link |
But dynorphin is also liberated
link |
from a certain number of neurons.
link |
Dynorphin binds to what's called the kappa receptor.
link |
The kappa receptor binds dynorphin
link |
and triggers pathways in the brain and body
link |
that lead to agitation, to stress,
link |
and believe it or not, to a general sense of pain.
link |
This is why you want to get out of the hot sauna.
link |
And remember, if it's unsafe levels of hot,
link |
then you should get out of that sauna
link |
or other hot environment.
link |
But if you're working in a range
link |
or you're exposing yourself to a range of heat
link |
that's uncomfortable but safe to be in,
link |
dynorphin will be liberated from these neurons,
link |
bind to the kappa receptor,
link |
and as a downstream consequence of that,
link |
there will be an increase in the receptors
link |
that bind the other endorphins,
link |
the endorphins that make you feel soothed,
link |
that make you feel happy,
link |
and that make you feel mild euphoria.
link |
So there've been a number of studies showing that initially
link |
deliberate heat exposure by sauna or otherwise
link |
causes the release of dynorphin.
link |
In fact, I think it's fair to say
link |
that every time we get into a hot environment
link |
that's uncomfortable or a cold environment
link |
that's uncomfortable,
link |
dynorphin is likely released
link |
and binding to the kappa receptor.
link |
that binding of dynorphin to the kappa receptor
link |
leads to downstream changes
link |
in the way that the feel-good endorphins,
link |
things like endorphin binding to the mu opioid receptor,
link |
and there are still other feel-good endorphins,
link |
That system becomes much more efficient
link |
such that people feel an elevation
link |
in their baseline level of mood,
link |
and when a good or happy event comes along,
link |
they feel a heightened level of happiness or joy or awe
link |
or improved mood in response to that.
link |
This is not unlike the effects of caffeine
link |
on the dopamine receptor that I've described previously,
link |
and for those of you that aren't familiar with it,
link |
many of you drink caffeine and love it.
link |
Part of the reason you love it
link |
is because of the release of certain neurochemicals
link |
like norepinephrine, et cetera,
link |
the energy that it gives you,
link |
maybe the taste, I would hope as well,
link |
but caffeine ingestion also causes increases
link |
in dopamine receptor concentration and efficacy.
link |
In other words, it allows the receptors for dopamine
link |
to work better so that for a given amount
link |
of dopamine release,
link |
you experience more pleasure and motivation.
link |
This is a similar mechanism,
link |
but within the endorphin pathway.
link |
So what does it mean?
link |
It means that a little bit of discomfort
link |
as a consequence of deliberate heat exposure,
link |
while in the short term doesn't feel good by definition,
link |
it is activating pathways that are allowing
link |
the feel-good molecules and neural circuitries
link |
that exist in your brain and body
link |
to increase their efficiency,
link |
placing you in a better position to be joyful
link |
in response to the events of life.
link |
I confess I'm very excited about the data
link |
on deliberate heat exposure and improvements
link |
in the chemical systems that underlie good mood.
link |
And just to underscore this further,
link |
the dynorphin system is not unique to heat-induced stress.
link |
In fact, there are beautiful studies and reviews out there
link |
about the role of dynorphin in stress and depression,
link |
in stress and alcoholism, just as a brief aside,
link |
and in the future, we will do a whole episode
link |
on alcohol and alcoholism,
link |
but turns out that chronic alcohol use and alcoholism
link |
causes changes in dopamine receptors
link |
that make it very difficult for people to achieve pleasure
link |
through things other than alcohol and even alcohol.
link |
That's kind of the really diabolical nature of addiction,
link |
which is the thing that initially brings pleasure,
link |
eventually is just required to maintain
link |
baseline levels of dopamine.
link |
And I've talked before, and Dr. Anna Lemke,
link |
when she was a guest on this podcast,
link |
talked about the pleasure plane balance
link |
that exists within the dopamine system.
link |
And it's beautifully described in her book,
link |
Dopamine Nation, by the way,
link |
excellent book I recommend to all people, addicts or not.
link |
Well, in that context of pleasure and pain,
link |
it's very clear what the pleasure molecule is.
link |
It's actually a molecule more related to motivation,
link |
and that's dopamine.
link |
The pain molecule, however, appears to be dynorphin.
link |
And the fact that dynorphin is dysregulated
link |
in stress and depression and alcoholism,
link |
and the relationship between dynorphin and dopamine
link |
is something that we should all take very seriously.
link |
And for that reason, I'm very excited about the fact
link |
that deliberate heat exposure
link |
can leverage the dynorphin system
link |
in a short-term and acute way
link |
that allows mood to improve after the sauna exposure.
link |
So for those of you that don't like heat exposure,
link |
keep in mind that a lot of the observed positive effects
link |
on our biology relate to metabolism,
link |
cardiovascular function, but also mental health.
link |
And along those lines, there's a wonderful study,
link |
again, published in 2018.
link |
I don't know why, I guess 2018 was a big year
link |
for deliberate heat exposure studies.
link |
The title of this study is Sauna Bathing
link |
and Risk of Psychotic Disorders.
link |
And this was a prospective cohort study.
link |
Again, we'll provide a link to this study.
link |
It's a really interesting study
link |
that explored the relationship between mental health,
link |
so people suffering from various forms of psychosis,
link |
schizophrenia and other forms of psychosis, and use of sauna.
link |
So essentially what this study did
link |
is they looked at a very large number of subjects,
link |
more than 2,000 subjects,
link |
who had no history of psychotic disorders.
link |
They were classified into three groups
link |
based on their frequency of sauna use,
link |
either once a week, two to three times per week,
link |
or four to seven times per week.
link |
This should call to mind that earlier study
link |
on all risk mortality and cardiovascular event risk.
link |
And then they explored the hazard ratio
link |
for psychosis specifically,
link |
meaning how likely it was that people
link |
would develop psychotic symptoms
link |
or full-blown psychotic illness
link |
according to their frequency of sauna session.
link |
So again, this isn't causal, this is correlative.
link |
And according to the data in this study,
link |
what they concluded is that there was a strong
link |
and inverse independent association
link |
between frequent sauna bathing and the future risk
link |
of psychotic disorders in this population.
link |
Now, this does not mean that going into a sauna
link |
seven times per week is going to prevent people
link |
from becoming schizophrenic necessarily,
link |
or from having a psychotic episode necessarily.
link |
And of course, frequent sauna use will be related
link |
to other health promoting activities.
link |
But in this study, as in the previous study,
link |
they went to great lengths in order to try
link |
and limit those so-called confounding variables.
link |
Now, of course, this is just one study.
link |
And again, it's correlative, not causal,
link |
but based on the large number of subjects they included,
link |
plus the rigor of the statistical analysis,
link |
we're starting to see a general picture
link |
that using the sorts of sauna protocols
link |
that I've described throughout this episode,
link |
five to 20 minutes or so done one to seven times per week
link |
is associated with a general improvement
link |
in cardiovascular health,
link |
a general improvement in mental health.
link |
And it really points to the fact that yes,
link |
sauna done acutely for three or four times a day,
link |
30 minutes each session separated by a cooling,
link |
maybe getting into cold bath.
link |
Sure, that can potently increase growth hormone,
link |
but done on a more regular basis can reduce cortisol,
link |
improve heart health, improve mental health.
link |
And for that reason, and the fact that for most people,
link |
it is conceivable to come up with a way
link |
that you could get into deliberate heat exposure
link |
for a minimum of cost, right?
link |
It's a hot bath, or if you had to resort to, you know,
link |
bundling up and going for a jog, this sort of thing,
link |
or if you have access to it, a sauna of some sort,
link |
that we're really talking about a stimulus
link |
to initiate a large number of different biological cascades
link |
that wick out to improve multiple aspects
link |
of brain and body health.
link |
So up until now, I've been talking about whole body heating.
link |
So for instance, putting your whole body into the sauna,
link |
which of course is what most people do,
link |
or getting into a hot tub or hot bath up to your neck,
link |
or in the cases where we were talking about
link |
deliberate cold exposure as a means to increase
link |
core body temperature and metabolism,
link |
getting into an ice bath or cold water of some sort
link |
up to your neck or into a cold shower, et cetera.
link |
Now I'd like to talk about deliberately heating
link |
or cooling specific parts of the body,
link |
meaning certain surface areas of your body
link |
as a means to get effects on those particular areas
link |
as well as at the whole body level.
link |
Numerous times throughout this episode,
link |
I've talked about the dangers of overheating.
link |
So what should you do if you think you or someone else
link |
is hyperthermic, is too hot?
link |
Well, if you understand just a little bit
link |
about the cooling and heating systems of your shell and core,
link |
there are some terrific tools that you can use
link |
in order to cool off your core quickly.
link |
And remember the core consists of the nervous system,
link |
the spinal cord and the viscera,
link |
which are really the organs you're trying to protect.
link |
So being able to cool off the core of your body quickly
link |
can be very beneficial and in some cases
link |
it could even save your life.
link |
There is a way to more quickly heat or cool the body
link |
and that's through specific elements of your shell,
link |
meaning particular skin surfaces.
link |
I've talked extensively about this in the episode on cold.
link |
It was also covered in the episode with my guest,
link |
Dr. Craig Heller from the biology department at Stanford.
link |
It relates to the so-called glabrous skin surfaces
link |
on the upper half of our face,
link |
palms of our hands and the bottoms of our feet.
link |
And for those of you that heard this before,
link |
I encourage you to continue to listen nonetheless
link |
because today I'm going to talk about specifically
link |
how to heat the body or cool the body
link |
through these glabrous skin surfaces.
link |
Very briefly, the mechanism is as follows.
link |
The palms of our hands, the bottoms of our feet
link |
and the upper half of our face
link |
overlies specific types of vasculature,
link |
meaning specific types of veins and arteries
link |
that don't have capillaries between them.
link |
And as a consequence, heat and cold can move very quickly
link |
from the palms of the hands, the bottoms of the feet
link |
and the upper half of our face
link |
and change our core body temperature.
link |
There's a name for these particular vascular structures.
link |
They're called AVAs or arteriovenous astomoses.
link |
Basically veins and arteries interacting directly
link |
without capillaries in between,
link |
which allows cooling of blood or heating of blood
link |
much more quickly than is possible
link |
by applying colder heat elsewhere on the body
link |
where capillaries intervene between veins and arteries.
link |
These AVAs, arteriovenous astomoses can be leveraged
link |
to cool off your core body temperature very quickly.
link |
The key thing is to get the palms of your hands,
link |
the bottoms of your feet and the upper half of your face
link |
in contact with a cold surface or fluid
link |
that is cold enough to cool the blood
link |
and the core of your body,
link |
but not so cold that it constricts the veins
link |
just below the palms of your hands,
link |
the bottoms of your feet or the upper half of your face.
link |
So not placing ice packs necessarily,
link |
but maybe placing cool towels on the bottoms of the feet,
link |
the palms of the hands and the upper half of the face
link |
and as they warm up,
link |
replacing those with other cool towels.
link |
The exact temperature will depend
link |
on how hot you happen to be.
link |
I can't know that without knowing your particular
link |
If you'd like to learn more about how to cool off your core
link |
very quickly and some of the details
link |
and some of the technologies that are being developed
link |
please see the episode I did with Craig Heller
link |
or the episode on cold.
link |
If you don't want to go to those episodes,
link |
here's a good procedure that you could use.
link |
You could grab, for instance,
link |
a package of frozen broccoli or frozen blueberries.
link |
If someone is really, really warm,
link |
make sure they take off their shoes and socks,
link |
get their feet on top of those,
link |
ideally get some into their hands as well,
link |
get some cool compresses and get them onto people's face.
link |
You could of course also put a cool compress
link |
on the back of the neck, on the top of the head.
link |
That would be an especially good idea
link |
if someone were hyperthermic because of the way
link |
that cooling of the brain occurs
link |
under conditions of hyperthermia.
link |
But the key point here is that just putting cold compresses
link |
or cold materials onto somebody's torso
link |
is not going to be as efficient
link |
as cooling those glabber skin surfaces,
link |
the bottoms of the feet, the palms of the hands
link |
and the upper half of their face.
link |
Similarly, or I suppose to be more accurate,
link |
I should say conversely,
link |
there are times when it is desirable
link |
to heat the core of the body.
link |
And once again, just simply throwing a hot towel
link |
over somebody is not going to be the most efficient way.
link |
If someone is hypothermic, they're too cold,
link |
it is not a problem to cover them with a blanket,
link |
but ideally what you do is you use some warm object
link |
or warm fluid to warm the bottoms of their feet,
link |
their hands and the upper half of their face.
link |
Of course, not so warm that you burn those skin surfaces.
link |
This has actually been examined in studies
link |
from the Heller lab.
link |
Turns out that for instance, to get people out of anesthesia,
link |
it is beneficial to warm their core body temperature.
link |
And of course there is fever,
link |
which you should know is an adaptive response.
link |
While fever is uncomfortable,
link |
and in fact often involves a mismatch
link |
between our perception of our shell
link |
and a perception of our core temperature.
link |
there are times when our body temperature is really high,
link |
we have a fever and yet we're shivering, we're cold.
link |
And that's because under conditions of fever,
link |
the immune system liberates certain molecules that impact
link |
and in some ways intentionally disrupt the preoptic area,
link |
the POA and the way it normally functions
link |
so that it can override peripheral signals
link |
and simply try and heat the body
link |
and kill whatever pathogen has infected the body.
link |
So for those of you that think about fever
link |
is always a bad thing, it's not.
link |
Now, of course we don't want our core body temperature
link |
to go so high that tissues of the brain and body are damaged.
link |
This is one reason why if a fever ever goes above 103,
link |
you need to start getting a little bit worried 104.
link |
There are times when you need to call an ambulance
link |
or go to a hospital.
link |
You really need to employ cooling methods
link |
of the sort that I talked about before
link |
to prevent hyperthermia.
link |
Of course, safe ranges for body temperature vary
link |
between infants and adults.
link |
So you can look those up online
link |
depending on the person's age,
link |
what is a safe range, what is not.
link |
But keep in mind that if you are taking compounds,
link |
pills to reduce your fever,
link |
you're actually short-circuiting the protective mechanism
link |
for burning up the pathogen.
link |
And that's because most pathogens, bacteria and viruses
link |
don't survive well at high temperatures.
link |
In fact, in laboratories,
link |
if we want to preserve a virus for use,
link |
we put it into a freezer.
link |
If we want to kill a virus, we heat inoculate it.
link |
So in many ways, fever is your natural form
link |
of heat inoculation designed to kill pathogens
link |
Now, last but certainly not least,
link |
I want to refer to the study that I described
link |
at the very beginning of this episode
link |
involving what's called local hyperthermia
link |
in order to trigger a number of biological processes
link |
in fat tissue in order to convert white fat to beige fat,
link |
which is the metabolically active form of fat.
link |
Many of you, or at least some of you
link |
should be familiar with the fact
link |
that deliberate cold exposure can increase brown fat stores,
link |
these mitochondrial dense fat stores
link |
that can in turn allow a person to feel more comfortable
link |
in cold temperatures, water or otherwise,
link |
and increase core metabolism.
link |
I talked about this in the episode on cold,
link |
but very briefly, the general protocol again
link |
is to get 11 minutes total per week of uncomfortable
link |
yet safe deliberate cold exposure,
link |
either through ice bath, cold shower,
link |
cold immersion up to the neck,
link |
or some other form of cold exposure.
link |
That triggers increases in brown fat,
link |
that's been beautifully shown by Dr. Susanna Soberg,
link |
and that increase in brown fat
link |
in turn increases core metabolism
link |
and one's ability to feel comfortable in cold temperatures.
link |
This was a study done in humans,
link |
and there's now ample evidence from animal models
link |
to support that this is a general phenomenon
link |
that I think most people could use and benefit from.
link |
Local hyperthermia is a distinctly different phenomenon.
link |
It involves heating a particular surface of the body
link |
as a way to convert the white fat at that location
link |
which in turn leads to more systemic increases
link |
in thermogenesis and increases in metabolism,
link |
and believe it or not, in fat loss.
link |
Now, the study that I'm referring to
link |
is a very recent study that was published again
link |
in this terrific apex journal, Cell, Cell Press Journal,
link |
and again, one of the three top journals,
link |
Nature Science and Cell are the three top journals,
link |
top because they're the most competitive,
link |
but also generally, not always,
link |
but generally the most stringent
link |
in terms of the review process,
link |
papers that make it into these three journals
link |
generally are a very, very high quality,
link |
and certainly enough people see them
link |
that if they're not of high quality,
link |
they get shot down pretty quickly
link |
in a short amount of time,
link |
whereas papers in other journals
link |
can sometimes last a long time
link |
before they're ever replicated, et cetera.
link |
The title of this paper is Local Hyperthermia Therapy
link |
Induces Browning of White Fat and Treats Obesity.
link |
This was a study that was performed on mice and humans
link |
in the same study.
link |
What the study involved was heating of a local patch of skin
link |
to 41 degrees Celsius,
link |
which is 105.8 degrees Fahrenheit,
link |
but not damaging the skin, okay?
link |
So the methods of heating did not involve
link |
placing something on the skin that would damage it.
link |
In fact, in the study on the mice,
link |
they used this kind of clever molecular chicanery
link |
in order to do it,
link |
and in humans, they used a thermocouple
link |
that would allow them to heat the skin up just locally,
link |
in particular locations on the body
link |
that I'll talk about in a moment.
link |
They refer to this process as LHT, or local heat therapy.
link |
The reason they did this is worth considering.
link |
It's long been known from clinical data,
link |
and in fact, from a bit of research data,
link |
that people that experience burn on a small,
link |
or unfortunately in some circumstances,
link |
a significant portion of their body,
link |
experience overall decreases in body fat
link |
and increases in metabolism that can last many years.
link |
Now, of course, is not reasonable,
link |
nor would one ever want to induce burn
link |
in order to induce fat loss,
link |
but the observed increases in metabolism and fat loss
link |
in response to skin surface burn
link |
couldn't be explained by reductions in activity
link |
related to the burn, for instance.
link |
And in fact, there are molecular pathways
link |
related to something called UCP1,
link |
which is uncoupling protein one.
link |
I talked about this also in the cold episode,
link |
but don't worry if you didn't see that episode,
link |
or if you choose not to.
link |
UCP1 has the ability to increase mitochondrial function
link |
in ways that increase core body temperature overall,
link |
in particular in beige and brown fat,
link |
which are these fat cells that exist
link |
generally along our spine,
link |
and in particular in the upper part of our back,
link |
and around our neck and clavicles,
link |
and they're responsible for acting as a sort of a candle,
link |
or I should say the fuel or the fat of a candle
link |
that can be burned up to manufacture heat in the body.
link |
So if you normally think about fat
link |
and you think about blubbery fat,
link |
you're thinking about white fat,
link |
which again is just a storage site.
link |
Beige fat and brown fat exist at just a few locations,
link |
mainly internally around our spinal cord and our clavicles,
link |
and those fat stores are responsible
link |
for generating heat in our body,
link |
so they are very metabolically active form of fat.
link |
Small children have a lot of brown fat and beige fat,
link |
in particular because very young children can't shiver,
link |
and a number of you probably didn't know that,
link |
but very young children can't shiver,
link |
so they need some way to generate heat
link |
in order to make sure that they stay alive
link |
if they were ever to get cold.
link |
This is also probably the reason why little kids
link |
can run around on a cold day outside without their shirt on
link |
and they don't even seem to notice
link |
whereas adults are freezing cold.
link |
As we get older, the amount of beige and brown fat
link |
tends to either reduce or shrink or disappear entirely,
link |
it's still debated, which happens,
link |
but we know that white fat can be converted
link |
to this more metabolically active form of beige fat
link |
by deliberate cold exposure,
link |
according to the protocol I talked about earlier,
link |
and now it seems, based on this new study,
link |
that local heating of skin tissue can also induce UCP-1
link |
and the effects of UCP-1 on increasing mitochondria,
link |
and in fact, that local hyperthermia,
link |
41 degrees Celsius, that is 105.8 degrees Fahrenheit,
link |
can actually induce the conversion
link |
of white fat to beige fat.
link |
Now that's pretty interesting,
link |
and I can already predict the way this is probably going to
link |
go in the kind of wellness and biohacking
link |
and longevity communities.
link |
I'm sure that pretty soon there are going to be
link |
people putting heating pads on different fat pads
link |
of theirs on their body, trying to reduce
link |
or at least convert the white fat into beige fat,
link |
and who knows, maybe that'll work.
link |
There have not been many controlled studies of this yet.
link |
This is the first, at least to my knowledge,
link |
of such studies looking at this in non-burn conditions.
link |
Nonetheless, the data are mechanistically
link |
even more interesting than this whole business about UCP-1,
link |
Local hyperthermia, using the protocol
link |
that I described before, resulted in the increase
link |
of a promoter, which is essentially a mechanism
link |
by which certain genes regulate their activity.
link |
This is a DNA binding of something called HSF-1.
link |
We don't have to go too deep into the mechanism here
link |
or the nomenclature, but HSF stands for heat shock factor 1
link |
and HSF-1 binding to a particular location in the genome
link |
allowed for a different molecule with a very long name.
link |
I'll just tell it to you for fun,
link |
but you can just let the numbers and letters stream by.
link |
It's not important.
link |
HNRNPA2B1 shortened to A2B1,
link |
which frankly is not that short to begin with.
link |
A2B1 is still a name that should be meaningless
link |
to most everybody, but here's what's really cool.
link |
A2B1 is directly involved in glucose and lipid metabolism
link |
and regulates the genes that control
link |
glucose and lipid metabolism.
link |
So here we have a situation where local heating of skin
link |
converted a metabolically sluggish or inactive cell type,
link |
the white fat cell, into the metabolically charging,
link |
so to speak, beige fat cell, which in turn led to systemic,
link |
meaning body-wide increases in metabolism
link |
through two mechanism.
link |
One mechanism is this increase in UCP-1,
link |
which for those of you that want to know,
link |
UCP-1 causes shifts in the way that potential energy
link |
is pushed from the protons through the mitochondria,
link |
basically more mitochondrial function,
link |
which means more ATP, which means cells are more active,
link |
AKA increased metabolism,
link |
and increases in things like heat shock factor one
link |
and A2B1, which are involved in lipid and glucose metabolism
link |
So I want to be very clear.
link |
This study does not say that spot reduction is possible
link |
with local heating of tissue.
link |
I just can see it now that once this paper gets out
link |
into the press, people are going to say,
link |
oh, heating up a certain patch of skin is going to burn fat
link |
or convert fat to some other cell type at that location.
link |
Sorry, that's not the way it works.
link |
They did observe increases in beige fat cells
link |
at certain locations in the body,
link |
but those increases in beige fat occurred
link |
where beige fat cells always reside,
link |
around the spine, the upper neck, the clavicles, and so on.
link |
This is exciting because it provides
link |
yet another potential mechanism
link |
in addition to deliberate cold exposure
link |
to increase beige fat, meaning the metabolically
link |
active form of fat cell.
link |
It also nicely provides a mechanism,
link |
or at least a potential mechanism for the observation
link |
that burn either small patch of skin being burned,
link |
or again, sadly, large patches of skin being burned,
link |
leading to these very extreme and very long lasting
link |
increases in body fat loss and metabolism.
link |
What, if anything, should you do with this information?
link |
Well, first of all, I want to very much caution people
link |
about putting anything so hot
link |
that it can damage the surface of your skin onto your skin.
link |
That would be a terrible idea.
link |
However, I do predict a time not too far from now
link |
where people will start to explore
link |
the use of local skin heating as a means
link |
to increase the conversion of white to beige fat,
link |
and in turn for beige fat stores
link |
to increase metabolism overall,
link |
and maybe even improve glucose metabolism and thermogenesis.
link |
If you'd like more details about this study,
link |
we will provide a link to it in the show notes caption.
link |
I should mention that the study,
link |
at least the portion of the study that was focused on humans
link |
involved roughly equal numbers of males and females.
link |
The subjects followed their normal daily schedule,
link |
including time and composition of meals, they say,
link |
rest and active hours, et cetera, et cetera.
link |
The local hyperthermia therapy was done in the following way.
link |
Here I'm paraphrasing from their method section.
link |
The subjects were seated in upright posture.
link |
They were wearing a standard test robe
link |
with the head and neck and shoulders unclothed
link |
and one meter away from a thermal imaging camera,
link |
which could basically measure the temperature
link |
at their skin surface to make sure that it remained
link |
constant across subjects and yet safe.
link |
The supraclavicular fat deposits,
link |
meaning the upper shoulders and upper back area
link |
were exposed to this thermal source,
link |
again, 41 degrees for 20 minutes, okay?
link |
So it was 41 degrees for 20 minutes
link |
and their core temperatures and skin temperatures
link |
were monitored before and after
link |
this local hyperthermic therapy.
link |
The subjects were exposed to this local hyperthermia therapy
link |
three days per week, separated by day,
link |
Monday, Wednesday, and Friday.
link |
So they had weekends off for five weeks total
link |
after which their data were collected.
link |
And the study has a number of other
link |
really interesting features that are sure to lead
link |
to increased understanding of both mechanism
link |
and new protocols such as analysis of the genes
link |
and proteins that are activated downstream
link |
of this local hyperthermia therapy.
link |
I find these data incredibly interesting
link |
in part because of the ways that local hyperthermia therapy
link |
mimics deliberate cold exposure therapy,
link |
same downstream mechanisms, UCP1
link |
and some of the other pathways are involved.
link |
And all of that points to a somewhat new
link |
but certainly an important concept.
link |
Many of you have probably heard of hormesis
link |
which is the subjecting of oneself or others I suppose
link |
to enough stress to induce an adaptation of some kind.
link |
So hormesis is the reason why
link |
if you get into cold water repeatedly,
link |
at first it's very painful psychologically
link |
and over time you get used to it.
link |
You never get completely used to it
link |
but you get more used to it.
link |
Hormesis is also used to describe the adaptation
link |
to cardiovascular exercise or to the hard rep sets
link |
of resistance training and the growth of muscles
link |
or the strengthening of muscles
link |
or the improvement in cardiovascular function
link |
to endurance exercise and so forth.
link |
Hormesis is a somewhat common term nowadays.
link |
If you haven't heard it, now you've heard it.
link |
In this paper they describe what is called mitohormesis
link |
which is in essence the fact that any number
link |
of different stressful stimuli provided they activate UCP1
link |
and some of these other pathways that I just described
link |
like HSF1 can induce changes in the mitochondria
link |
that lead to increases in metabolism.
link |
So it shouldn't surprise us that cold and heat
link |
can both lead to increases in metabolism
link |
and conversion of white fat to beige fat.
link |
It shouldn't surprise us because both pathways are stress.
link |
Local hyperthermia is stress, burn certainly is stress,
link |
sauna is a form of stress,
link |
deliberate cold exposure is a form of stress,
link |
exercise is a form of stress
link |
and the adaptation to those stressors is not infinite.
link |
All of those protocols, any protocol for that matter
link |
is going to be effective because it's going to converge
link |
on an existing internal biological mechanism.
link |
So there's no unique mechanism for each protocol.
link |
Each protocol that I've talked about today
link |
whether or not it's five minutes or 20 minutes
link |
or four times in a day or three times per week
link |
or seven times per week is tickling or pushing
link |
or stomping if you will on a given pathway
link |
and really activating it to a milder to severe degree.
link |
What I've tried to do today is to illustrate
link |
the general mechanisms by which heat in particular
link |
can activate certain biological pathways
link |
so that you can devise protocols
link |
that are going to be optimal for you and your needs.
link |
So just to briefly recap,
link |
if you want to get the greatest growth hormone increases,
link |
do sauna or other deliberate heat exposure fairly seldom,
link |
probably no more than once per week, maybe even less
link |
and do it a lot that day,
link |
just make sure that you break it up into multiple sessions.
link |
In the study I described earlier,
link |
they did four sessions, 30 minutes each,
link |
but that was just once a week.
link |
If you're interested in the cardiovascular benefits
link |
and the potential longevity benefits of sauna,
link |
well then it's clear that doing it three to four,
link |
maybe even seven times per week
link |
is going to be more beneficial than doing it
link |
just one or three times per week.
link |
It stands to reason that for those of you interested
link |
in the general health effects of sauna,
link |
about an hour per week broken up into three sessions
link |
makes the most sense based on my read of the data.
link |
And again, that range of 80 to 100 degrees Celsius
link |
is going to be your guide.
link |
And in terms of the mental health benefits,
link |
it seems that getting a little bit uncomfortable
link |
in that heat environment, sauna or otherwise,
link |
provided it's safe is going to be the best way
link |
to access those mental health effects
link |
by way of increasing dynorphin, which as you recall,
link |
will then increase the ability of endorphin
link |
to have its positive effects on mood
link |
after you get out of the sauna
link |
or other deliberate heat exposure.
link |
And in terms of timing,
link |
after a workout of any kind, morning or afternoon,
link |
or if you're not doing it after a workout,
link |
certainly in the later part of the day
link |
is going to be most beneficial as it relates to sleep.
link |
But of course, there's a caveat there,
link |
which I will mention again,
link |
which is that for those of you that have no trouble sleeping
link |
because you're exhausted
link |
or you're just one of these phenomenal sleepers,
link |
well then do it any time of day or night.
link |
But for most people doing it later in the day
link |
is going to be more beneficial
link |
because of the post sauna cooling effect
link |
and the relationship between cooling by a degree or more
link |
as a way to enter sleep.
link |
Thank you for joining me today for my discussion
link |
about the science of heat and heating for health.
link |
If you're learning from and or enjoying this podcast,
link |
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link |
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In addition, please subscribe to the podcast
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link |
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