Essentials: Benefits of Sauna & Deliberate Heat Exposure

I'm Andrew Huberman and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine.

“Today we are talking about the science of heat. Heat is a remarkable stimulus, meaning when we are in a hot environment, it has a profound effect on our biology.”

So we're going to talk about the science of heat and heating both in terms of their mechanisms. And as I know many of you are interested in, the tools related to the use of heat, things like sauna, how often to do sauna, how long to be in the sauna, how hot to be in the sauna for particular goals and outcomes. We heat up two ways. We heat up from the outside, meaning the things that we come into contact with, the clothing that we put on our body, whether or not there's heat in the room or whether or not it's cold outside or cold in a room, and we heat up from the inside.

At every point across your entire lifespan, you have two distinct temperatures. One is the temperature on your skin, what scientists call your shell, and the temperature of your core. Your viscera, meaning your organs, your nervous system, and your spinal cord. It is vitally important to understand that you have those two temperatures, and that your brain is constantly sending out signals to your body, as to whether or not it should heat up or cool down depending on the temperature of the shell.

So anytime we're talking about heat, meaning deliberate heat exposure, things like sauna, it's very important to understand, not just the stimulus, how hot something is, how long you're in a sauna, etc. But the effect that has on your shell and on your core. If you can understand that, you can design protocols that are literally perfect for your goals.

“A brief warning now and another brief warning later, any time you're talking about heating up your body, you need to be very cautious,”

because I'm like cooling down where you have a fairly broad range of cold temperatures that you can go into before it's damaging to tissue. Well, you don't get to heat up the brain and body very much before you start getting into the realm of neuron damage. And neurons in the central nervous system, the brain in spinal cord, once they're damaged, they don't come back. So hyperthermia is a serious thing to avoid. There's a very basic circuit, meaning neurons that exist in the skin, in the brain, and the body that communicate with one another, that allow you to heat up if you need to and cool down if you need to.

Once you understand the circuit and the way it's structured, then you are going to be in a great position to use the tools related to heating.

So here's how this circuit is structured. You have this shell, which is basically skin.

“And within the skin, you have neurons, nerve cells. Those nerve cells have channels or receptors on them.”

They're called trip channels. There are some other ones as well, which basically sense changes in heat. So if I were to put a hot object on your hand or your arm or, for instance, if I were to put a hot object on your hand or arm and then remove that hot object, those neurons would respond to that. They would send electrical signals into your spinal cord. And that's where the next station of the circuit resides. In your spinal cord, you've got a cluster of neurons that exist at the top part of your spinal cord,

called the dorsal horn. The name again doesn't matter. And those neurons specifically relay heat information up to another area. If you're brain, now here's where we get into some fancy names. It's the lateral parabricial area. You don't need to know lateral parabricial area, but it's a relay station. The lateral parabricial area sends electrical signals to the POA. And I would like you to know POA. The POA stands for pre-optic area.

Neurons in the pre-optic area basically reside over the root of your mouth. These are neurons within the hypothalamus.

And neurons in the pre-optic area have the ability to send signals out to the rest of your brain and body to get you to heat up and actually to change your behavior. So there are all these different mechanisms by which we dump heat. Some of those are purely physiological. Below our conscious control, things like sweating, which you can't just make yourself sweat on demand. Maybe you can through a set of stressful thoughts, but you can just make yourself sweat. That is autonomic. It's below your conscious control. Things like vasodilation, the dilation of your veins in particular in capillaries in particular.

And of course, there are these behavioral somewhat voluntary aspects of dumping heat. And the lethargy, the kind of tiredness that we feel on a really hot day, that's also controlled by this circuit that I just described. The impulse to get yourself out of a very hot environment is the consequence of the POA communicating with your amygdala. And the amygdala then in turn activating your adrenal glands, which are sit right above your kidneys, the release of adrenaline,

So now you know the circuit. Again, it simply goes from skin to spinal cord, one brain area to another brain area that's the key one in this discussion, which is the POA, the pre optic area.

“If you can conceptualize that circuit, or if you can even just understand what I just said, even at a top contour level, you're going to be in a great position to understand the rest of the information and the tools that follow.”

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The use of deliberate heat exposure can be a very powerful way to improve health and longevity.

There's a wonderful study on this. There was published in 2018 that includes a lot of data from a lot of participants in a lot of different conditions.

“For instance, people that only did sauna once versus two to three times a week versus four to seven times a week, and so on.”

And compare as all those. The title of the study is sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women. A prospective cohort study. This is one of several papers that clearly demonstrate. That regular use of sauna or other forms of deliberate heat exposure can reduce mortality to cardiovascular events, but also to other events, things like stroke and other things that basically can kill us. What I like so much about this and the related studies is that they involve a lot of participants.

In this particular paper, which was published in BMC Medicine, they looked at a sample of 1,688 participants. We had a mean age of 63, but there was a range of ages around 63, and of whom 51.4% were women, the rest were men. So it's a pretty nicely varied study in terms of the populations that they looked at.

Basically what they found was the more often that people do sauna, the better their health is, and the lower the likelihood they will die from some sort of cardiovascular event.

Now, what do we mean by sauna? We need to define some of the parameters around sauna, and I promise to provide you some alternative ways to access some of the health benefits that were observed in this and related studies without the need to have a sauna because I do realize that a lot of people don't have access to sauna. First off, the temperature ranges that were used in this study, and pretty much all the studies that I'm going to talk about, unless I say otherwise, are between 80 degrees Celsius, meaning 176 degrees Fahrenheit, and 100 degrees Celsius, meaning 200 and 12 degrees Fahrenheit. So somewhere in that range, how hot should you make the sauna or the environment that you get into, should you decide to use these tools?

Well, that will depend on your tolerance for heat, how heat adapted you are. Yes, some people are better at sweating than others, and over time, we all get better at sweating, meaning if you go into the sauna more frequently, you become a better sweater. That's what you wear, but the verb sweater. You get better at sweating at dumping heat through the loss of water. So it's going to depend. I recommend starting on the lower end of the temperature scale, and if that's too hot for you, that you even lower the temperature further. Now, how long were people exposing themselves to these hot environments anywhere from five to 20 minutes per session.

In particular, study, they compared the effects of people that did sauna once a week, two or three times per week or four to seven times per week. What they observed was that people who went into the sauna two or three times per week were 27% less likely to die of a cardiovascular event than people that went into the sauna just once a week.

And in fact, the benefits were even greater for people that were going into the sauna four to seven times per week.

“Those people were 50% less likely to die of a cardiovascular event compared to people that went into the sauna just once a week.”

It's nice about this study and the related study is that they looked at a number of potentially confounding variables, things like whether or not people smokes, things like whether or not people were overweight, whether or not they tended to exercise or not exercise. And they were able to separate out those variables. So the percentages that I described earlier, those effects really do seem to be the consequence of the sauna exposure and not some other effect that's correlated with sauna exposure, like going to the gym where people are working out seven times a week.

And then also happen to get into the sauna or quitting smoking right about the same time they adopt a sauna protocol, these sorts of things.

And now there have been additional analyses of the use of sauna for improving health where I should say for offsetting mortality that have found that it's not just reductions in cardiovascular events, but so called all cause mortality. This is kind of medical geek speak for saying how likely are you or somebody to die from a cardiovascular event, but maybe also from some other event, some other health related event like cancer or something of that sort. And in every case, regular exposure to sauna starting at about two or three times per week all the way up to seven times per week.

Rightly improves, meaning statistically significant improvements in longevity in the sense that people are less likely to die of cardiovascular events and other things that kill us.

You don't have to use a sauna in order to get these benefits. It is simply a matter of making sure that your shell and your core heat up properly, not too much, not too little that you heat those up.

“That's how are you heating up your environment and I realize that there are dry saunas, there are steam saunas, there are infrared saunas, there are hot tubs and there are simply rooms that you crank up the heat.”

There are also ways in which you can increase your shell and your core temperature by moving around a lot and doing that wearing a lot of clothing. And nothing special about any one of these approaches or protocols. It's just so happens that sauna is one of the more convenient ways to do this. And certainly for the studies that I've talked about, not just the ones I referenced before, but all the studies that I researched, look at this episode. It makes sense why they would use sauna because it's very hard for instance to create conditions where you have, you know, five people go out jogging, wearing heavy sweaters and hats will hats on the middle of summer.

It's very hard to set up those conditions in a way that's controlled for everybody, whereas it's pretty straightforward to have a sauna where you have one or several people just get into that one uniformly hot environment. That's a much easier study to run. You could, however, immerse yourself in a hot tub or hot water bath up to your neck. That's another way to approach it. If you didn't have access to either of those, you could also put on a hoodie or wool hat and a hoodie or you could do like the wrestlers do and you could actually buy one of these plastic suits.

“They're literally called plastics that wrestlers or other athletes that wish to drop water weight will wear and then go jogging that all of those will increase your shell and your core body temperature, right?”

Especially if you do it on a hot day, but of course be careful, hydrate and don't overheat, don't become excessively hyperthermic because you can get heatstroke and you can potentially die. So what happens when you get into a hot environment? What are the mechanisms that allow for the various health effects of that? So blood flow increases, plasma volume of your blood increases and stroke volume, the volume of blood that is mobilized with each beat of your heart also increases and your heart rate increases to anywhere between 100 to 150 beats per minute.

That general constellation of effects looks a lot like cardiovascular exercise. And in fact, for all intents and purposes, it really is cardiovascular exercise, except that there isn't the mobilization and the loading of joints and limbs and things of that sort. There are additional benefits of cardiovascular exercise that relate to impact on the ground, improvements in bone density, et cetera, et cetera. But basically your heart starts beating more blood start circulating. Your vasculature changes shape literally to accommodate those increases in heart rate and blood volume. And you're basically getting a cardiovascular workout in that hot environment, even if you're just sitting down.

The positive effects related to being in these hot environments are hormone effects shifts in the output of hormones both from your dreamals and possibly from the testes and ovaries and even within the brain.

The study was, in this case, just an unmen. I'll just briefly describe the protocol they use.

They had these men attend four sauna sessions of 12 minutes each. So again, well within that range of five to 20 minutes, 12 minutes. The temperature of those saunas was 90 to 91 degrees Celsius. That's 194 degrees Fahrenheit and they did that four times. Afterwards, they had a six minute cooldown break during which they did get into some cool water or cold water of about 10 degrees, which is 10 degrees Celsius is 50 degrees Fahrenheit. And then they measured hormones at various times throughout this study before during and after.

The major effect of this study is a significant decrease in cortisol output in these subjects.

“I think this is really interesting and important because many people suffer from acute, meaning immediate and long-term stress and are looking for ways to control their stress.”

Controlling your cortisol is tricky. Many people are overworked, they're overstressed. For one reason or another, they're subjected to many too many stressors or their level of stress resilience isn't high enough to keep their cortisol levels clamped at a healthy level. So the protocol I described of 12 minute exposures to 90 degree environment, that's again 90 degrees Celsius, followed by a six minute cooldown break in cool water, 50 degrees or so. That's pretty cold. I can imagine that you could also just take a cool shower or a cold shower afterwards, that had a very significant effect on lowering cortisol.

So there you have a tool. It's not a completely zero cost tool because you need to heat the water and you need to have access to hot and cold water, at least hot and cold contrast of some sort.

But it's fairly minimal cost for most people, especially if you start getting creative about maybe taking a 12 minute jog, wearing a lot of clothing. If it's hot out, then getting into a cool shower. You might not get the same extreme or significant reduction in cortisol that was observed here with these very specific protocols, but it's likely that you would get a similar result overall.

“So if you're seeking to use sauna to reduce stress, I think this is a very interesting and potentially useful research back protocol. And again, we will provide a link to the paper, if you'd like to read more about the data.”

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“One of the more dramatic and important effects of going into a hot environment for some period of time is the activation of so-called heat shock protein, or HSPs.”

The shock proteins are a protective mechanism in your brain and body to rescue proteins that would otherwise misfold. What do I mean by this? Well, most of your familiar with the fact that if you have protein in the kitchen, like a steak or a piece of chicken or a piece of fish, and you heat it up, it changes its texture. Raw meat is different than cooked meat. Heat changes the quality of proteins, not just in terms of how they taste, but the way in which they are configured. It changes it right down to molecular level.

When your body goes through changes in temperature, in response to hot environments or cold environments, heat shock proteins are deployed to go and rescue and prevent the changes in proteins that would be detrimental to your health. So, at least in the short term, activating heat shock proteins is a good thing. You don't want heat shock proteins to be activated for long periods of time, because that gets to be problematic for other reasons.

And they also sort of a protective mechanism, making sure that proteins within the cells of your brain and body don't fold in the wrong ways.

“Again, I'm describing this in very general terms, but it's well established in animal models and in humans that sauna exposure of the sort that I described earlier activates these heat shock proteins.”

There have been interesting studies done in humans examining some of the downstream molecular pathways of deliberate heat exposure that point to the mechanisms by which deliberate heat exposure can help protect against different forms of mortality, improve health overall, and possibly, and I want to highlight possibly, possibly extend life.

One such mechanism involves a genetic program involving a molecule called FOXO3. FOXO3 is a very interesting molecule because it's involved in DNA repair pathways.

DNA repair is part of the process of remaining healthy. You know, we'd all like to think that we're born and based on the genes we have, we are healthy healthy healthy, then eventually we age, and then we die. But from the time we're born until the time we die, there's a constant repair of our proteins and ourselves in a modification of the genes that are being expressed.

“You know, puberty being the most dramatic example, right? You see a kid before puberty and after a period looks like a different kid sounds like a different kid. Things like a different kid, in fact, basically is a different human being, right?”

It's not just the hormones, it's that hormones themselves have the capacity to turn on and turn off certain genes, literally converting certain tissues and cells in the brain and body to do entirely different things.

And DNA, the stuff of genes, gets damaged in that process. FOXO3 sits upstream in a pathway related to DNA repair and again clearing of these centers and cells.

Sona exposure, in particular, Sona exposure, 2 to 3 times or ideally 4 to 7 times per week, in that 80 to 100 degree Celsius range has been shown to upregulate levels of FOXO3.

“In turn, upregulates pathways related to DNA repair and clearing out of these centers and or dead cells, which is known to be important for various aspects of maintaining cognition and other aspects of maintaining health.”

So these are the likely biological mechanisms for the improvements in lifespan or I rather, I should say, these are the biological mechanisms that apparently offset some of the cardiovascular risk and other forms of mortality that were described earlier. One, especially interesting thing about FOXO3, there are individuals out there that have either additional copies of FOXO3 or who have versions of FOXO3 that are hyperactive, so to speak, those people tend to be 2.7 times more likely to live to 100 years of age or longer.

So these are people that were just naturally, unfortunately, for them, endowed with more FOXO3, more clearance of senacen cells, more DNA repair, et cetera. Deliberate heat exposure is one way that you can increase FOXO3 activity. There is no Sona protocol designed specifically to reduce cortisol or specifically to increase FOXO3 or specifically to activate heat shock proteins. Any deliberate heat exposure is likely to impact all of those mechanisms. Again, I encourage you to use this guide of 80 to 100 degrees Celsius as your kind of bookends for what you can tolerate and where you want to start and eventually transition to in terms of deliberate heat exposure, and I would encourage you to use that 5 to 20 minutes per session for the Sona as your rough guide of how long to remain in the Sona.

Now I'd like to talk about the use of Sona to increase growth hormone. Growth hormone impacts metabolism and growth of cells and tissues of the body. It is responsible for tissue repair as well and the growth expert that everyone experiences during puberty is the consequence of growth hormone. What I'm about to describe is a study that found dramatic, really dramatic, I should say, increases in growth hormone. But I also want to emphasize that these increases in growth hormone were not of the sort that are observed in puberty or in infants becoming adolescents or adolescents growing into teenagers.

This levels of growth hormone that are associated with those massive transformations, excuse me, of body morphology of shape are far greater than the sorts that I'm talking about here. And yet, as all of us age, when we go from adolescents to their teenage years and then into a young adulthood, but then starting in our early 30s or so, the amount of growth hormone that we secrete is greatly diminished.

Certain forms of deliberate heat exposure using sauna can stimulate very large increases in growth hormone output, which for people in their 30s, 40s and beyond could be very useful and may also be useful for people who are just trying to stimulate the release of more growth hormone in order to, for instance, recover from exercise or stimulate fat loss or muscle growth or repair of a particular injury.

“The title of this paper is endocrine effects of repeated sauna bathing, and this is a paper that was published in 1986, which is some years ago, but nonetheless serves as a basis for a lot of other studies that followed.”

They used an 80 degree Celsius environment, so that's 176 degrees Fahrenheit. They had subjects do this sauna for 30 minutes, four times per day, so that's two hours total in one day, 30 minutes in the sauna, a period of cooldown rest, 30 minutes in the sauna again, cooldown rest, a third and a four time, okay, so two hours total in this 80 degree Celsius environment, so that's a lot, but what they observed was really quite significant. And I should mention they had both male and female subjects in this study, and the entire study lasted a week. They did this two hours of sauna exposure on day one, day three and day seven of that week, and they measured a lot of different hormones.

I'll just cut to the chase and tell you the effects on growth hormone. In subjects that did this two hour a day 80 degree Celsius protocol, experienced 16 fold increases in growth hormone. So they measured growth hormone before the sauna and after the sauna and growth hormone levels went up 16 fold, which is obviously an enormous end, it turns out statistically significant effect. One important caveat here. Remember earlier when I talked about people who did sauna once a week versus two to three times a week versus four to seven times a week, and the more often people did sauna, the less likely they were to die of cardiovascular vents or other things of that sort.

Well, in this case, the effects of sauna exposure on growth hormone actually went down the more often that people did this deliberate heat exposure. So as I mentioned, they did this two hour a day divide in the 30 minute sessions protocol on day one, day three and day seven of a week. And they found was on day one, there was a 16 fold increase in growth hormone. On day three, however, there was still a significant effect on growth hormone as compared to before sauna, but that effect was basically cut by two thirds.

Now instead of getting a 16 fold increase, it was more like a three or four fold increase, which is still a huge increase, but not as great as the increase observed on day one. And then on day seven, they're tended to be a two, maybe a three fold increase, but not as great as the one observed on day one. The fact that that result diminished over time, either means that the circuit was not as efficient in communicating that shift in temperature, or that that shift in temperature was of less impact because the downstream effectors were not engaged to the same extent because it wasn't as much of a shock.

“I think the latter explanation is far more likely. This is very much akin to weight training or cardiovascular exercise, where if you run up a hill very fast, for instance, and your lungs are burning and you're heaving and breathing hard.”

On the first day, that's a very painful thing, but if you do it every day or every other day, pride you allow yourself to recover, pretty soon you're running up that hill and you're not breathing as hard. There is a much burning in your muscles, et cetera, et cetera. Your body adapts. So if you're going to use deliberate heat exposure in order to try and trigger massive increases in growth hormone, you're going to need to be careful about not doing it more than, let's say, once a week. Now, I'm extrapolating from this study, maybe once every ten days would be even better, but if you start getting heat adapted, it's very unlikely that you're going to get these massive increases in growth hormone.

So I don't mean to be discouraging of using deliberate heat exposure to access growth hormone increases, but if that's your specific goal or your main goal, then I think it's reasonable to say that you don't want to do deliberate heat exposure, at least not of the sort that I described here, more than once a week, or maybe even once every ten days.

“You would want to time that to other events in your life, maybe hard workouts, or if you're trying to push through a fat loss barrier, or simply in order to access growth hormone at peak levels, maybe three times per month or four times per month.”

If you start doing deliberate heat exposure more often, you'll still get increases in growth hormone, but they are not going to be nearly as large as the increases in growth hormone that you're going to experience if you shock your system with deliberate heat exposure every once in a while.

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“When you decide to do sauna or cold exposure for that matter is going to be important.”

Why? Well, if you were to make the surface of your body cold, at least in the immediate period, after that your body temperature will increase, and that can make it hard for some people to fall asleep.

Now, if you're very, very tired, because you've been working hard or training hard or both throughout the day, you might not throw off your sleep so much.

I've gone through bouts where I'm just so, so busy from morning till night that the only time I can get into the ice bath of the cold shower is late in the evening, and I have no trouble sleeping after that. If you're going to use deliberate heat exposure, you'd be wise to do it later in the day because when you get into a warm environment, sure, the surface of your body, the shell heats up, the core of your body heats up, but then it also activates cooling mechanisms through the pre-optic area. And when you get out of that hot environment, sauna or otherwise, your body will continue to cool down, and so many people find that if they do sauna in the later half of the day or even just before sleep.

And then take a warm and shower afterwards, then they find it easier to fall asleep, and that makes sense because their body temperature is dropping. And in fact, if your goal is to really promote the maximum amount of growth hormone release, that's also going to be the best time of day to do it, especially if you have an eaten in the two hours before sleep. So if you're really going for growth hormone release, you're really trying to optimize sleep, and the two things are actually linked because of the release of growth hormone that happens from the pituitary in the early nights.

Well, then you would be wise to do your sauna, maybe once or maybe twice a week in the evening, or at night time, then taking a warmer, cool shower, just briefly, just enough to kind of rinse off all the sweat from the sauna, and then get ready for sleep. And to do that, not necessarily fasted, but to try and keep your levels of glucose and insulin somewhat low in your bloodstream. The reason I say that is that having elevated blood glucose and/or insulin tends to blonde to reduce growth hormone release, and that's true for any number of different stimuli, including exercise and including sauna.

If you really want to crank out the most amount of growth hormone in response to sauna, do it fasted, or at least not having ingested any food in the two or three hours before. You don't have to be deep into a fast. I think for 90% of people, 90% of the time, just getting into the sauna once or twice or three times a week is going to be beneficial for the number of reasons that I described earlier, and you don't want to obsess too much about the exact conditions you need in order to get the greatest effect out of that sauna treatment.

“Now, regardless of what time of day you do sauna, or how frequently you do it, you're going to want to hydrate after going in the sauna. When you go in the sauna, you lose water, and when you lose water, you need to replace it. Why?”

Well, you need water for all your cells, but you also need electrolytes, so make sure that you're replacing the water that you lose in the sauna. Now, there's no exact formula of how much water to drink, and whether or not you need electrolytes in that water or not, it's going to depend on how much you sweat, meaning how heated adapted you are, it's going to depend on how much salt you tend to do it. You're sweat, huge amount of variation, but in general, one way to approach this would be to make sure that you drink at least 16 ounces of water for every 10 minutes that you happen to be in the sauna. You could do that before and during end after, you could do it during and after, or you could do it after.

Now, there are other reasons to do deliberate heat exposure that have improvements in mood and mental health. You'd have related to sauna and other forms of deliberate heat exposure, improving mood are very impressive, both at the mechanistic level, and in terms of the long-term consequences that people experience. First of all, we need to ask, how is it that deliberate heat exposure can improve our mood and well-being? Well, it turns out that it improves mood and well-being, but it also improves our capacity to feel good in response to things that would ordinarily make us feel somewhat good.

What I'm talking about is the upregulation of pathways, meaning chemical pathways in your brain and body that allow you to experience pleasure in all its fullness.

Many of you have probably heard of endorphins. Endorphins are a category of molecules that are made naturally in your brain and body, and that are released in response to different forms of stressors. That's right, and response to stressors. So, ever you've gone out on a long run, and at some point that run, you feel like you're aching and your joints hurt, or maybe you have shin splints, and you push through that. Part of the reason that you experience a lack of pain at some point, usually, or you experience a euphoria during or after that exercise is the exercise induced effects on endorphin release, or rather to be more specific.

Like I should say, the exercise induced consequences on the stress system, which in turn trigger the release of endorphin. In other words, when we experience short-term or acute stress, the endorphin system is activated. The endorphin system is not just about feeling good, believe it or not, it's also about feeling bad, and there are two general categories of endorphins.

The first are the ones that you normally hear about, endorphins, things that bind for instance to receptors like the mu opioid receptor.

We make endorphins that naturally act as pain relievers, and that make us feel mildly euphoric. We also make endorphins, such as die-norphin, that's dy-n-o-r-phyan, die-norphin, that actually make us feel worse in response to stressors. When we get into a hot sauna or a hot environment of any kind, die-norphins are liberated in the brain and body. And I should mention that die-norphins are made by many neurons in many different areas of the brain.

“It might think, well, why would I want that? Why would I want to release die-norphin into my brain and body?”

Well, first of all, when you get into an uncomfortably hot situation, uncomfortably hot scenario, oh gosh, this is sounding terrible,

a deliberately hot environment that you are using to try and trigger some sort of biological or psychological benefit, I should say, the discomfort that you feel.

The desire to get out of that environment is in part the consequence of the release of die-norphin. It's also the consequence of the activation of that sympathetic nervous system. Remember, the pre-optic area can communicate with the amygdala and trigger that kind of fighter flight mode. I want to get out of the sauna, this is really, really hot, but die-norphin is also liberated from a certain number of neurons. Die-norphin binds to what's called the capa receptor.

The capa receptor binds die-norphin and triggers pathways in the brain and body that lead to agitation, to stress, and believe it or not, to a general sense of pain. This is why you want to get out of the hot sauna.

“And remember, if it's unsafe levels of hot, then you should get out of that sauna or other hot environment.”

But if you're working in a range or you're exposing yourself to a range of heat that's uncomfortable, it's safe to be in, die-norphin will be liberated from these neurons bind to the capa receptor. And as a downstream consequence of that, there will be an increase in the receptors that bind the other endorphins. The endorphins that make you feel soothe, that make you feel happy, and that make you feel mild euphoria. It's fair to say that every time we get into a hot environment that's uncomfortable or a cold environment that's uncomfortable,

die-norphin is likely released and binding to the capa receptor. But over time, that binding of die-norphin to the capa receptor leads to downstream changes in the way that the feel good endorphins, things like endorphin binding to the mu-opiod receptor, and there's still other feel good endorphins, so to speak. That system becomes much more efficient, such that people feel an elevation in their baseline level of mood, and when a good or happy event comes along, they feel a heightened level of happiness or joy or awe or improved mood in response to that.

So what does it mean? It means that a little bit of discomfort as a consequence of deliberate heat exposure, while in the short term, it doesn't feel good by definition. It is activating pathways that are allowing the feel good molecules and neural circuitries that exist in your brain and body to increase their efficiency, placing you in a better position to be joyful in response to the events of life.

“We're starting to see a general picture that using the sorts of sauna protocols that have described throughout this episode, right?”

Five to twenty minutes or so, done one to seven times per week, is associated with a general improvement in cardiovascular health, a general improvement in mental health. And it really points to the fact that yes, sauna, done acutely for three or four times a day, 30 minutes each session, separated by a cooling,

But done on a more regular basis can reduce cortisol, improve heart health, improve mental health.

“And for that reason, and the fact that for most people, it is conceivable to come up with a way that you could get into the deliberate heat exposure for a minimum of cost,”

right? It's a hot bath, or if you had to resort to, you know, bundling up and going for a jog, this sort of thing, or if you have access to it a sauna of some sort, that we're really talking about a stimulus to initiate a large number of different biological cascades,

that weak out to improve multiple aspects of brain and body health.

Each protocol that I've talked about today, whether or not it's five minutes or twenty minutes or four times in a day or three times per week or seven times per week, is tickling or pushing or stomping if you will on a given pathway and really activating it to a milder to severe degree. What I've tried to do today is to illustrate the general mechanisms by which heat in particular can activate certain biological pathways,

so that you can devise protocols that are going to be optimal for you and your needs.

So just a briefly recap.

“If you want to get the greatest growth hormone increases, do sauna or other deliberate heat exposure fairly seldom.”

Probably no more than once per week, maybe even less, and do it a lot that day just make sure that you break it up into multiple sessions. And the study I described really did four sessions, 30 minutes each, but that was just once a week. If you're interested in the cardiovascular benefits and the potential longevity benefits of sauna, well then it's clear that doing it three to four, maybe even seven times per week is going to be more beneficial than doing it just one or three times per week. And again, that range of 80 to 100 degrees Celsius is going to be your guide.

And in terms of the mental health benefits, it seems that getting a little bit uncomfortable in that heat environment, sauna or otherwise,

“provide it safe is going to be the best way to access those mental health effects by a way of increasing dinnorphin,”

which, as you recall, will then increase the ability of endorphin to have its positive effects on mood after you get out of the sauna or other deliberate heat exposure. And in terms of timing, after a workout of any kind, morning or afternoon, or if you're not doing it after a workout, certainly in the later part of the day is going to be most beneficial as it relates to sleep. But of course there's a caveat there, which I mentioned again, which is that for those of you that have no trouble sleeping because you're exhausted or you're just one of these phenomenal sleepers,

well then do it any time of day or night. But for most people doing it later in the day is going to be more beneficial because of the post-sana cooling effect and the relationship between cooling by a degree or more as a way to enter sleep. Thank you for joining me today for my discussion about the science of heat and heating for health. And last, but certainly not least, thank you for your interest in science.