Welcome to the huberman Lab podcast, where we discuss science and science based tools for everyday life. I'm Andrew huberman and I'm a professor of neurobiology and Ophthalmology at Stanford school of medicine. Today, my guest is dr. Suzanne us oberg dr. Suzanne has oberg completed. Her doctoral thesis work at the center of inflammation and metabolism and the center for physical activity. Research at the University of Copenhagen in Denmark, her research has focused on how deliberate.
Old exposure and deliberate heat exposure can be used to enhance human metabolism. She is the first author of a seminal study which discovered the minimum thresholds for deliberate heat and deliberate cold exposure for increasing Brown fat thermogenesis, which is essentially a mode of increasing heat production and Metabolism in the body and for establishing actionable protocols. That can be used outside of the laboratory to improve metabolism and human health, dr. Silber's research was published in the journal cell.
Reports metabolism in 2021 adding to a long and important history of research focusing on the role of cold and the role of heat in altering various aspects of the body's physiology, including Hormone Health metabolism, and changes in neurotransmitters such as dopamine and epinephrine. In fact, today's discussion with dr. So Berg focuses on the role of deliberate heat and deliberate cold exposure on metabolism, but it also includes discussion of the effects of cold and heat on things like neurotransmitter production.
Namely, dopamine, and epinephrine, and norepinephrine. The so-called catecholamines, which strongly impact mood and Metabolism in addition. Dr. Shoberg answers. Many common questions about deliberate cold and deliberate heat exposure. Including, for instance, the difference between cold showers versus cold immersion up to the neck versus total body cold immersion, including whether or not going back and forth between heat and cold changes fundamentally. The way that heat and cold impact the metabolism hormones and neurotransmitter production.
And we talked about almost every single nuance and variation on deliberate cold and deliberate heat, exposure, protocols, as it relates to the underlying science, in particular, how cold receptors at the level of the skin are impacted versus cold reception and perception at the level of the brain and how all of that impact systems of the brain and body relating to mental health, physical, health, and Performance, Based on her, scientific research and academic training, as well as her understanding and use of deliberate.
Heat and deliberate cold exposure, protocols, dr. Zoidberg is considered one of the world's leading experts on these topics. In fact, she is the author of a recent book entitled winter swimming, which is I have to say a terrific book because it breaks down chapter by chapter the different aspects of deliberate heat and deliberate cold into its various constituent Parts, including cold, acclimatization the cold shock response, dangers, and safeties of cold water, the impact of cold and impact of heat on various
Of human health as well as specifics relating to Sauna versus Ice versus cold swimming showers Etc. It's a very thorough read in a very easy and accessible read that if you are. Interested in deliberate colder, deliberate heat, exposure or both will allow you to embrace those protocols with the greatest degree of confidence that you're going to obtain the specific endpoints that you're interested in and to do so safely. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is however,
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Once again, that's huberman labs.com. Tour and use the code huberman to access tickets. I hope to see you there and now for my discussion with dr. Suzanne us, oberg dr. Susanna Solberg. Welcome. Thank you, so, great to have you here, I feel like I should give a little bit of the back story of how we got connected, which was that for many years, I've been interested in cold thermogenesis, it was the topic of my senior thesis and college. And of course, followed the popularity,
Of Wim Hof and we've had dr. Craig Heller, my colleague from biology department at Stanford who works on cold and its impact on physiology and sports performance. So, for a long time, I've been interested in this area but there's been a real lack of new. Let's say high-profile quality, scientific information, in terms of how for instance, cold plunges and sauna how that impact human physiology
I know there's been some information out there but it's been sort of scattered and then a little over a year ago I see this paper in cell reports medicine and was immediately struck the. First of all the fact that it was in cell reports medicine I've been on the cell precedent editorial board for a long time now. So press journals are of course phenomenal journals and the title and the content of the paper was directly in line with the sorts of practices that people are very curious about and they're starting to emerge things like
On a cold plunges and there was your name first on the author list and I reached out to you through social media and we've done a little bit of live content there together and I've been tracking what you've been doing in the world in terms of your book and talking about the results in your manuscript and talking about the science and impact of deliberate cold exposure and Sona. And I have to say that it's been a wonderful and remarkable thing to see, and you're bringing so much quality information about this area that for a long time, I think was
Has kind of Niche and is now becoming more and more mainstream. So I'm going to start off with a, thank you for being here, and I thank you for the work that you've done and I'm looking forward to talking to you about it today. So my first question to get things started is what is happening when we get into an uncomfortably cold environment. So for instance, if I'm really hot on a hot day, jumping into a cold pool feels really good, but if I'm
Ready kind of at room temperature? I'm a little bit chilly, getting into that, same temperature of water doesn't feel so good. Right. There's a shock there. So if you could just walk us through what happens when we get into uncomfortably cold water, whether or not it's by way of shower or cold Plunge at the level of our physiology and if you'd like our psychology I think that's a good place for us to start because I think it will Orient people to their own experience if they do that and for those that haven't done it might start to peel back some of the layers as to what the underlying.
Lying mechanisms of cold are?
Yeah, thank you for that question. It's really good to just address what actually happens in our physiology when we get cold and you can get cold in many ways. So you can just head out for the one that gives you the most potent. A stressor, which is submerging into cold water. And, but you could also go in outside in the cold wind, that's also going to activate your sympathetic nervous system. So, get all these new transmitter going in your body and so your
Catecholamines, let's just address that. We are taking a cold plunge for example. So if you are very hot for example, before you go into the cold water is going to feel less is going to feel this stressful, but the temperature difference from your skin to the cold is definitely going to give you a shock but your core temperature is warmer and that's going to feel a little bit better. So that's why when people go into a sauna for example and go out than in into the cold water, they
They can do it easily easier than if they were cold beforehand,
could I just ask you a few questions? So you mentioned the sympathetic nervous system which for people listening who aren't familiar with that. Is that the branch of our nervous system that's responsible for creating accelerations and heart rate feelings of alertness. It's accompanied with stress and the stress response, but it's accompanied with waking up in the morning for that matter. So, it's not always about stress. And then you mention the catecholamines, which
Our dopamine epinephrine and norepinephrine. So, maybe a little bit later, we'll talk about those individual neurotransmitters, but you raise a really important point, which is something I get asked about a lot for people that are curious about using deliberate cold exposure, which is how cold should the water be. And I know it's very hard to give a straight prescription for that because I think it boils down to what you just said, which is, it's really the difference between your current temperature and really the temperature of the surface of your skin and the temperature of the water. So if you're very warm
Even the cold feels good. If you're already cold getting into more cold. Feels stressful, is there any way that we can start to gauge? What is the best way to approach a deliberate, cold, exposure protocol? I mean, should it feel uncomfortable and that leads into the question of how do we balance the discomfort with the amount of time that we spend in? So, for instance, if it's just a little bit uncomfortable, will spending more time in the cold, get us the same benefit as getting into very uncomfortably cold.
Water for a very short period of time.
Yeah, it's really good question and I definitely think that this could be a future studies on this, as well, to really unravel. What kind of Protocols are the other best way? Or also for which outcomes, of course. So if the temperature is very cold and you feel that you're also feel very cold then you should stay in the water a little bit longer. So I think it's just, you should get uncomfortable code. So as long as you get
Uncomfortable cold, it's cold enough and you get this what we call the code shark. So the coast sock is activation of your sympathetic nervous system and these activation of the catecholamines, which you just mentioned before,
is the shock mean that I'm having trouble controlling my breathing is that a good
gauge? Yeah, you can say. So because that's kind of like how we Define it, so you hyperventilate. So you have a faster breathing rate. So, that increases also, because you act
A job, gasping reflects. If you are new to this, but if you are adapted, it kind of subsides with time and with a meditation so what you can do is that you can train this cold exposure and you can kind of like Get adapted to it. So you don't have this hyperventilating response every time you go out in the cold water. So this is like building up your resilience building, building up your adaptation is going to make this short like subside a bit. So it's it's
As harder in the beginning, but you should do hard things, right? It's not something that we shouldn't think about cold water and cold water immersion as something. That is comfortable. It should be hard because that's the point of it. Right? If you enjoy it, then yeah. Then I'm I'm thinking something is wrong. It's not right, you should not enjoy it. Well, this is an important point that you're making because I think that many people shy away from deliberate cold exposure, because it's uncomfortable in a way that at least from my experience is very different than the discomfort of exercise.
Because with exercise for instance if running hard you know running fast and breathing hard is uncomfortable, you can slow down or walk. If you know lifting weights is uncomfortable you can remove some weight or reduce the number of repetitions or stop with deliberate cold exposure. I suppose you can be sort of halfway in halfway out of the water or partially underneath the cold shower, but it's very hard to titrate and adjust the level. So it's kind of
All or none. And I've seen she just I can tell this by anecdote. I've done some work with military Special Operations, I won't say which country this was outside the US and these are very tough individuals. They're used to going without sleep and doing hard high consequence. High-risk kind of work and they were asked to do some cold water exposure training and I was there that day and it was remarkable about a third of them just went straight in and he's kind of guy.
I did through it, you know, like they look stoic anyway to me, there were a few whimpers, no cries about a third talked, a lot and got really. You could tell that they were agitated and anxious, but they made it through. And then, about a third of them, just simply would not get in past their knees, or thighs. We're just, it seemed like they were just dreading the whole experience. Some actually didn't actually go in completely, which was really surprising to me. And not you couldn't tell based on their physical appearance or anything else.
About them. They're all high performers as to who would have this response. So it seems like people vary tremendously in terms of their ability to embrace the discomfort of the cold. Is that from your studies? Is that your experience as well or? Or they're these weird mutants who seem to just love going into the cold for the first time.
So some people just feel better in the cold and some people read the code even more and you can say the more people are pushing the cold away, they might feel the copain even
They they would definitely people who are, maybe the soldiers you just talked about. They, some of them might be already adapted to the goal cold. So if they are not scared of the cold, they go out and they embrace the cold in a better way. It could also be that some people have a more sensitive nervous system and when you are a bit sensitive to the cold you will of course try to get away from it. Right? And you will also have the copain more feel the cold paid more if they're if
If you avoided. So the more you avoid the cold, the more pain painful it will feel when you go into it. So yeah,
you mentioned being outside in a t-shirt versus cold immersion up to the neck versus shower. I think this is something a lot of people wonder about what are the differences in terms of impact short-term, and perhaps even long-term between cold showers, cold plunge to the neck. So, that could be a nice water, just very cold water.
Immersion with dunking one's head and then coming up because obviously, we will have to come up for air at some point and then simply being outside on a cold day in shorts and a t-shirt or something of that
sort. So, do different outcomes because there they are very different exposures of the cold to York of receptors in your skin. So the more you can say, you cover your body in the cold, which you would do in cold water, because there are, of course,
Cover totally. And the molecules that are closer to your skin, you will have a more potent activation of or your coat receptors in the skin. So that one will definitely activate your autonomic nervous system more and Rapid compared to going out in a t-shirt in the cold wind, just go for a walk but that is also something that's going to activate your sympathetic nervous system. Meaning them that you have an increase in
Or pain Efren and you will activate something called the brown fat. So this is a healthy kind of fat tissue that we have in our body and when you activate that, that's going to increase your metabolism.
Before we talk about Brown fat and I'm so glad you brought it up because it's so much to talk about there. What about cold shower? I mean, obviously cold shower somewhere in between being out, outside in the Air Cold Air versus being immersed up to the neck. If we had
Studies on Co showers, we would learn more about. How does that activate our metabolism? How does that increase our neurotransmitters in the brain, which could also have an impact, our on our mental balance. So, I think that would be interesting for the future, but what we do know is from from, from activating, Brown fat, and both from rodents total studies, but also in humans is that as soon as we get cold on our skin, we will activate our Brown fat.
So it is kind of like our first responder in the body to keep our temperature up. So I'll muscles is like the second tissue in our body are two tissues, which can increase our thermogenesis. So the brown fat, which is like always like temperature regulating our body, and then we have the the muscles which will secondarily start to shiver and that's going to increase our temperature in the body. But as soon as you go into a cold shower, you will activate
Your brown fat is also immediately, so it could be good. Also for increased metabolism in theory because we haven't really any studies showing how much this actually activate the brown fat. So, if someone out there wants to do a study, I think
I thought about why there are fewer studies of cold showers and cold immersion. And I think the answer to my mind is that from a methodological standpoint, it's just harder to do because if people are getting into cold water up to the neck, they're getting into cold.
Water up to the neck. Whereas, if people are getting into a cold shower, some people are larger or smaller. Some people are going to stand under the shower with a hitting their head. Some people the back of the neck you could direct people to do it. Yeah. But it's a little bit more difficult. Also I think for you and I are both research scientists, there's a little bit of a methodological challenge that might seem silly to people, but it's a real one, which is, if people are in a cold shower, also, the water is going to be. I'm kind of pushing their clothing against their skin, there's a certain vulnerability, and for most people
Coming to a laboratory in the first place, let alone being observed while they shower res. When you get into cold emerge in cold immersion, you're getting under the water and you know some people might roll their eyes and say okay, really is that the barrier but you know science exists in these real-world context and this will vary by culture and things of that sort. But we run human subjects in my lab and I'll tell you just the process of getting people to the laboratory and having them Park and find the lab and you know, it's a whole new environment with people in lab coats and people moving around. And Where's the restroom? I mean it
There's there's a certain amount of stress just associated with taking part in a study for most human subjects, so I totally agree. However, we need more studies of cold showers. It's just a harder environment to control in my mind. So it sounds like any form of cold to the skin, that people register, as what you call the cold shock or an uncomfortable. Like, like this is kind of jarring activates the brown fat. Do we know what the pathway is from coal?
Receptors on the skin to the brown fat. I mean, how does the brown fat know that we're
cold? Yeah, really good question. And it seems that I think that, of course in the future, we will know much more about these Pathways. But what we do know, is that the code was sceptres will send a signal to our temperature, regulating Center in the brain, so hypothalamus, and that's going to be taking in this message and we have so many cold receptors in the skin. So, it's going to be very fast as you can say, if you immerse the body into,
A water. This is going to be so rapid, so it will have a rapid increase in neurotransmitters, in the brain to know, adrenaline, adrenaline cortisol and, which is not that much, but it's but it's still there. So, you have this increase in noradrenaline, which will then immediately, activate the brown fat because the, you can say, the activator is the most potent. One cold and noradrenaline, that's going to activate the brown fat, but there's also a direct pathway from the coke
Scepters in the skin, to the, to the brown fat, which releases shows that if because of these different Pathways, it shows that that it could be that this tissue to keep us warm or was developed in our evolvement as humans to keep us warm and to save us whenever the temperature now on our skin, Barry suggested little bit to keep us in that right homeostatic balance. So we don't get hypothermic but also
so we don't get hyperthermic but it because it seems that the brown fat is also activated when we get warmer now skin. So it's also maybe a temperature regulator in our in our body but the pathways is different. I think it's also third pathway from directly from the muscles so the brown fat is also activated even though the muscles are starting to shiver. So there was a an extra pathway that way to keep our temperature up so muscles and brown.
Working together to keep us warm. So we don't suffer too much in the in the cold
water. Super interesting and what I hear you pointing to is the existence of three parallel Pathways and this notion of parallel Pathways comes up over and over again in biology as you. And I know. And I mean, I think it's important for people to know about because, as you said, so, so eloquently, the when something is very important to our survival or and or Evolution the brain and body
Install multiple mechanisms for it, not just one and and so it sounds like it's cold skin, cold on the skin triggers and response in the hypothalamus which then activates Brown fat cold receptors, in the skin directly to the brown fat and then shivering in the muscle to the brown fat. I want to talk about Brown fat in depth and learn from you more about round fat. Before that. However, I want to ask about shiver, I've heard
That shiver causes the release of succinate which then activates the brown fat? Is it known whether or not inducing? Shiver is important. And when should people Shiver? I mean, I've gotten into cold plunges and shivered while I was in there. And then I've also had the experience of getting into a cold plunge or a cold shower, then getting out or even standing outside on a warm day after swimming in a pool and then starting to shiver. So the shiver comes later. So how important is
Shiver and does it matter when shiver happens.
Yeah, it was shivering is good because that increases your metabolism and that was going to burn some calories in your body. You shouldn't be so afraid of shivering. I think because the Shivering as long as you don't get to hypothermia. So if you don't, if you don't sit in the cold water for too long and what you just said by shivering, after you get up that is because of the, after drop something called the after drop is when your core temperature decreases, even after you get out of the cold water, and it always does that your
Because it soon, as you get into the cold water, all the blood vessels, this going to constrict because you need to keep your blood in your core and and keep your vital organs warm. So as soon as you get up that those blood vessels will open again and the warm blood would flow out and get colder, and then flow back again into the car. And that's going to decrease the temperature in your core, of
course. So that's the drop. So that's the draw. I'm so glad you explained that I've heard you.
As ago, when Hoff, I heard him talking about the drop. And I've heard colleagues of mine, talk about the drop, but that's the first time I've ever heard it explained. Clearly living. Let me make sure I understand this, so I get into cold water. Obviously, I'm cold vessels constrict to keep blood near the center of my body. Keep me alive, I get out the warming up of my body, allows those vessels and capillaries to dilate again. The blood goes out to the surface but the surface is still cold and so that blood
Cooled and then my core body temperature drops. And that's what you're referring to as the drop. And that's what induces shiver. Exactly. And then am I right? In thinking that then the shiver activates Brown fat which then warms me up again. Yes, God
is why you should end on the cold. We could get back together.
Let's talk about ending on cold. As you know, it's what I refer to as and what has now become known as the so Burg principle, which is a really important principle about the importance of ending on cold and not doing what I do, which is
Just to get into a hot shower or back in the center but we'll get back to that in a few minutes. So that's wonderful that you can explain that. So clearly because I think that shiver is something that a lot of people do, avoid people think oh I don't want that, you know the chattering of the teeth and and it feels like a loss of bodily control which really it is. It's an autonomic response.
Yeah but I don't think that people should avoid it that much. It's just like seeing shivering as a way of your body in.
Like its training, it's training for your folio cells is training for your muscles. It's training off your metabolism and that's going to increase your What's called the insulin sensitivity. So if you can like in your mind get used to. The thought of shivering is just like when you go exercising in the training center and get that feeling of like oh this is tough now it hurts a little bit. Yeah it's going to hurt because that's what shivering also does but it's just a different way of training your cells in your body. It's going to
Create what is healthy stress? Is called hormesis in the cells and the more you expose your muscle cells or your brown fat cells to these kind of like healthy, stresses exercise, cold and heat exposure. It's going to make them better at like activating and also keeping you healthy. So as long as the cells get exposed to this, the it's going to keep them on its toes. You can say because it becomes more robust and increasing these heat shock proteins and kosher.
Was in the cells to make you a more robust for the next time and that is also what happens when you go to the training center and I keep like drawing that parallel because Pub people today know more about windmill more about exercise and what that's it's going to do to your muscle cells. And and but the same kind of like training is also what you do when you go out and into the cold water and submerged into cold water, because that is just your code training.
Center. You can see and and also your heat Training Center going into the sauna because the cells are getting stronger with hermetic stress. So it's the same process just different practices.
I'm so glad that you brought up the fact that the discomfort or the embarrassment or both of shiver is still crucial to actually to reach for and try and experience the same way that it with exercise. I think a lot of people don't realize this, but when we did our series with dr. Andy Galpin.
It became clear to me. What should have already been clear to me? And I think that most people don't realize, which is that if we were to measure, heart rate, blood pressure, stress, hormones and inflammation in a human being during exercise, it would look as if they were ready to die, blood pressure would be high, inflammation is through the roof. But all of that is setting in motion and adaptation or set of adaptations that allow blood pressure to be lower at rest, that allow inflammation markers to be lower at rest.
All the things that everybody is seeking with exercise. And in addition to, of course, the aesthetic changes that people are seeking with exercise. Sounds like the exact same things are happening with the cold. So the Redundant message here seems to be that the more discomfort provided it's done safely just like with exercise the more shivering the the more cold shock provided it's not to the extreme and stop somebody's heart, right? We can talk about thresholds for that little bit later. It sounds like all of that is going to set in motion.
Some long-term changes that will make people feel better and will improve health. Could you just touch on a few of the longer term changes that are known to occur? I mean, I'm well aware of the study showing that I think was European Journal of physiology. It was the European Journal physiology showing long-lasting increases in catecholamines, dopamine norepinephrine and epinephrine for many hours after deliberate, cold exposure. What are some of the other things that happen at the level of metabolism and brown fat?
In, let's say the hours and day after a deliberate cold exposure
as soon as you go in, of course there's an activation but it seems like, no, you're asking for the later outcomes like blood pressure and stuff like that. Is that what you mean?
Yeah, blood pressure but also in terms of metabolism, I know that you know, in your study you should and will talk about Brown fat in-depth here in a moment, but that there were changes to the brown fat that equate to changes in, for instance, people's ability to be comfortable in colder environment.
It's when they're not doing deliberate cold exposure or in the same way that I can exercise on an exercise bike or go out for a hard run. But then if I go hiking with the family on Sunday and it's a steep climb, I could do that steep climb more easily because I'm quote-unquote fit as a consequence of the of the exercise. What are so what are some of the fitness adaptations of deliberate, cold exposure?
Yeah, so what happens is that you you get adapted a little bit every time you go, so you will like, exercise, get a Little Bit Stronger.
So every time you go into the cold water for every time you will be more exposed to a durable, you feel more comfortable in the code. So you're going to, you're going to build your adaptation, which happens on a metabolic level, which is going to be the brown fat. So, we'll have more activation of your brown fat. The mitochondria, in the brown fat cells are going to be you have more of those and they will be more efficient at heating you up because it expects the body expect you to do this again. So you are prepared in a way. The capillaries in your
Your skin is also key will also become better at like constricting so you will have a better Shield of your body to prepare you for the next time. So we will be become better at going into the cold water in that way. So the body makes these mechanism and changes your body in a way. So you can expose yourself to the next time, right? And and also you will have also a your stress response will also be subside a bit. So you have
Less increase of your catecholamines with time with time. Also you have because of this activation of your brown fat or your muscles, you haven't increased in in your metabolism which will then make your insulin sensitivity better. And this is shown in studies, for example, there's this interesting study, I found just before I started my PhD, which was from keeper, stoma it Al from
16, where they measured metabolism, not in, or not on Brown fat, but they measured insulin. Sensitivity in middle-aged men, and women during one winter swimming season. So, they were not very young, like they were in my study but they were, they were middle-aged. And I think this is very interesting. So they during these four, five months, they were winter swimming. They saw that they had a lower blood pressure after the season and they had a lower heart rate and they
I was so so that they have a better insulin sensitivity, and I think that is very interesting, because if you can have a better insulin sensitivity, you can prevent lifestyle diseases. So, and we lower blood pressure, which is a very strong outcome. Also for telling how much inflammation who have in the body, and because it didn't measure Brown fat, I figured that it could be, that was the missing link. That was the one of the explanations to why we see this?
Less inflammation in the body. So the longer outcome. So the long-term outcomes could be that you lower your blood pressure and have a lower heart rate. You also have a better insulin, sensitivity, and better glucose balance, but that was shown at that is shown in my study.
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Packs in the year supply of vitamin D3 K to will get back to the insulin sensitivity and glucose balance. That's a in an impressive list of benefits, you know, blood pressure. Of course, most people are aware of blood pressure and what it is. It's what they measure when we go to the doctor and it's not very sexy. Nowadays, you know, blood pressure being honest, you know, blood pressure. It's not, you know, people want to hear about the inflammatory ohm and the microbiome, and all of that stuff is really interesting, but I think that blood pressure doesn't get enough.
Enough attention, and we have spoken to on this podcast to dr. Peter attia, who is an expert in longevity, and health span, and things of that sort. And and I was surprised to learn. Again I shouldn't have been surprised that the number one reason people died worldwide is cerebral, vascular disease and cardiovascular disease and they're basically three things on the list of things to address. One is not smoking or vaping, by the way. Not
Get that there are a few other things related to blood markers apob and things of that sort. But then the big one is blood pressure. And so, it's interesting because we don't think about blood pressure that much anymore as a kind of people interested in health optimization and health, but blood pressure is so vital to control. So, it's wonderful to hear that deliberate cold. Exposure is one way to control blood pressure. I'm guessing in concert with other forms of exercise. Let's talk about Brown fat and
And if you, if you're willing, I'd love to drill into Brown fat at a deep level. Again, my understanding of this is far more Elementary than yours. Obviously, you're the expert. My understanding about round fat is that it's located in specific areas of our body. May be more widespread than when I learned in school. I thought it was. I was taught it was just at the clavicles in the back of the neck and upper back but who knows? I learned that there's more of it when we're children may be.
Distributed throughout our body and that it's rich in mitochondria. But what is so special about the brown fat? Like, if we could just go into the biology of brown fat, a little bit, what does it look like? You've measured it in human subjects. Where is it distributed? Really? Can it expand its distribution? Can we activate and expand the amount of brown fat as adults? And for those of you that are cringing already thinking, we're talking about getting fatter, it's quite the opposite. We're talking about not,
Subcutaneous fat butt, fat located around the organs but please educate me. Tell me where I'm wrong and expand my knowledge on Brown fat.
Okay? Yeah, you are not wrong but it's definitely it's true. That there are more locations of the brown fat than we previously. Thought there's this very nice study from 2017 by Lightner Adele where they had made these festivities overlays of their subjects
But you can see where in the body do we have brown fat and where can we grow more Brown fat? So to say, so the brown fat is, is very plastic. So it means that it can grow and they can decrease. And this is proven in, in studies, where we have seen them people, with their failed kryos. I Toma is like a very specific candidate type where people were from the Seven Seas where we can see that if they have this specific kind of cancer,
Type, they have at it, they have this tumor on the adrenal gland. So they have like, an a huge increase in noradrenaline and because of that, they have this continuous activation of the brown fat and they have grown a lot of brown fat. In whole body are abdominal where it's located in this six different places, but it is less like very much compared to like normal people. And what they didn't see what we learned from this study, is that brown fat can
Apparently grow. If you have an increase in noradrenaline the body. It's not like you want that because when that happens, you have a high blood pressure. You don't want to chronically, right? You just want it on like a short amount of time and then it can grow for a bit, but you don't want to chronically, of course not. But because it activates also your sympathetic nervous system. So they also showed they have high blood pressure. They had they lost a lot of weight, of course because this is activating your metabolism. So they they found luck.
Ali that when they remove this bit benign tumor that, the brown fat decreases again to normal size and they gain weight again and they had normal blood pressure. So the story ends well, but it's kind of like proof of concept of the brown fat can actually grow. So it's plastic in its in its way of like it can grow and it could decrease again so that's very good. Good studies to see what what the body is capable of but we don't of
Was want all that brown fat. We just wanted to be, just want to keep it actually and keep it activated. Because what we see in studies is also that after the age of 40 and people Studies have shown that there is an association with having less brown fat, but increase obesity. So, of course, we don't know. Yet whether Brown, fat decreases with Ace and therefore, we get obese or we get obese and therefore, we have less brown fat. But as
Brown fat is an insulin sensitive organ in our body and we get beasts just like the muscles. Get less sensitive to insulin sensitive, the brown fat does as well. And therefore, it may be decreases. It could be a theory that I think could be one of the reasons why we don't see that much Brown fat in elderly. People, some have a lot specially people working outside. There are studies showing
this who people who worked out
Outside do physical work, outside farmers.
And yeah, interesting, yeah, yeah. Thanks to those them. So to it. So they'll just keep it in that way.
It's an I suppose we should clarify for people in case. They don't know that insulin sensitivity is a very good thing. You want that you want yourselves to be sensitive to insulin. Insulin insensitivity is type 2 diabetes, and as associated with obesity. So just a point of clarification there,
Yeah, it's interesting to me, I usually work out at home but I go to a gym once or twice a week if I can because it's good if I see the outside world and there are a few individuals at the gym who are they're not particularly large or muscular, but they are incredibly lean and their posture is great. Presumably from the musculoskeletal work and they they're in there.
70s and 80s. I mean, it's remarkable, right? And, and I know all The Tell-Tale signs of hormone augmentation. I'm very good at spotting that there are few telltale signs. I've talked about this on other podcasts and they're not there. That's not why they're there. They're there fit there, they are clearly of that look. And you see this written outside the gym to, of course, for people that look like they've done a lot of physical labor, their whole life. Yeah, they're just moving a lot. They have strong hands and features and they're, and they're not necessarily.
Excessively lean but you can tell that they've been using their musculoskeletal system and I like to talk to these people and ask them like not what are you doing now for your workout? But what what did you grow up doing? You know, and I would say and obviously I've been run statistics on this but more than 75% of them respond that they grew up on a farm or that they did some sort of
Manual labor, or were a postman, or a post woman or doing something where they moved a lot for their early years and throughout middle age. And most of them are now in retirement, but some of them are still working and they all still moving a lot. So, the relationship between shiver and brown fat makes sense to me. But is it the case? That as we're just moving around, I'm I've heard of needs non exercise-induced thermogenesis. So if we're just moving around, that we are activating Brown fat.
At or does there need to be this stress, or does there need to be shiver and a cold stimulus or a heat stimulus to activate the brown fat? In other words is just staying active enough or do we need to do some sort of temperature shock type thing like deliberate cold expert exposure?
Yeah, I think that is really good question because how, how also why do we have this tissue? Then if it's if it has to be extreme then you can question what what do we need this tissue for, but it seems that you can activate
The brown fat with just a little bit of exposure to cold, the coldest of the most potent. Stressor activator of our Brown fat, because it's our temperature regulating organ in our body. So first responder to that? So the muscles will be a little bit too late and therefore, we have maybe these two kind of tissues. So, actually, just exposing yourself. Our hand actually just too cold water. So Studies have shown that if you just put your hand in cold water, not that you're going to going to do that all day or
every day or anything. It's not the it's not something you have to do, but it just shows that you can activate your brown fat, just by getting a temperature change on your skin, so you can go outside and t-shirt. That's why also we were just talking about. Well, people who works outside or move a lot, get in and out of it, like changing the temperature of the body all the time, they will have more Brown fat and activating that it's going to keep your metabolism higher. And your insulin sensitivity is
They have also shown that so the brown fat can be activated as soon as you just change your temperature in the skin, so going outside in a t-shirt wearing cooling vests. Also Studies have shown this for 10 days, it's going to also grow your your brown fat. So you can get more Brown fat. If you expose yourself to the cold, you don't have to start in a code shower, you don't have to start in a cold plunge, if you're not really ready for that yet. But just exposing yourself to the wind has also shown
Shown to activate your brown fat or if you don't want to be like in this wake State, then you can also just sleep in the code and you won't notice it that much. Maybe, but Studies have shown that. If you sleep in 19 degrees Celsius, then you will activate your brown fat and you will grow your ground fat. So you have more of it. So this very nice studies from Hanson. It out from 2017 showed that a group of sir.
Guess who slept in a room at 24 degrees and then they made this PET CT, scanning, to see how much Brown fat do they have from the beginning. So what we call Baseline, then they measured again after a month of sleeping in 90 degrees. And they saw, I think it's remarkable just one month at 19 degrees sleeping. There they had a to bet on and they were still had clothes on when we're sleeping so
they're under a cover under
event under the bed. Yeah, the subjects were sleeping at 19 degrees from one month had
Increased is insulin sensitivity. The next month they stepped at 24 degrees, they measured this again, and then they had decreased actually a little bit and then they slept at the 27 degrees. So quite warm room actually for, for the fourth month, and they saw even less activation of the brown fat, and also insulin sensitivity. So, it seems that you can expose yourself and pretty rapidly. The brown fat will respond to this because it's so sensitive to noradrenaline, right?
So, if you keep exposing yourself to a little bit of coal, you also get a little bit adapted to it, but that's because the brown fat has grown these more mitochondria in the cells. So these small energy Fabrics that's going to activate the cells and that's going to take up glucose and fat from the fatty acids from the bloodstream to keep the thermogenesis arc, and that's going to clear up some sugar and it's going to click a, so in the, in the bloodstream and some some fat as well. So the brown fat can
In that way, decrease, our unhealthy fat, which is the white fat and the white fat is what we don't want too much of. But we still need some of course, and it's our energy storage. So it's very important that it's there. We just don't need a lot of it. So now thighs and also around our inner organs, that's where it's located. So, if we can have activation of the brown fat just by going out in the cold and just by sleeping in a cold room, or if you are have courage for it, you can go
Expose yourself in a cold plunge, cold showers is also going to do the trick. So you can do different variations of this just exposing yourself to various temperatures. It's going to activate the brown fat because it was involved to keep us in a perfect homeostatic balance regarding temperature. So, to Keep Us Alive,
incredible. I just get a clarification around this 19 °C room that they're sleeping and so they're under a comforter duvet.
And you mentioned, they had clothes on the room is 19 degrees Celsius, but the temperature underneath their blanket might not be 19 degrees Celsius. So presumably it's the cold on their face. That's activating the, the increase in brown fat. That was observed. Is that? Is that a reasonable
expectation? I think so. Yeah, because it's, you have so many cover scepters in your face as so, it's actually, it's enough and I think corresponds very well with the studies showing that you can activate the brown fat.
By putting a hand into a bucket of cold water and I did this experiment myself in my studies just to see how well did they respond to cold water. So it was a 4 degrees Celsius, cold water for 4 minutes and then I just missed your blood pressure and heart rate to see. Do they have like an activation of this? I actually also measured the brown fat during this cold exposure for four minutes with an infrared. Thermography camera to see can I see that the brown fat is
Activated and just just to tell go back to the location of the brown fat. So, usually, you cannot really see activation of your brow, because it's located centrally in your around your central nervous system. And, and the biggest Depot as you mentioned before, is up here under the clavicular bones. So, and very close to the skin surface and because it's so close to the skin surface. I could measure it with this very expensive camera.
And it's not very feasible for people to go home and do this. It don't because it takes a lot of practice. I can tell, but we measured the brown fat with this. And I could see that after a few minutes that the activation, was there an increase in temperature arose from that activation just four minutes. So, it's very rapid. And I'm also measured in my study, how deep was the brown fat under your skin? So it's very close to the surface which also shows that it needs to be.
Therapy to hit you off and he your inner organs.
Well, I'm delighted to hear all of this and I'll tell you why. One is, by way of anecdote, I mentioned a little bit earlier that, as an undergraduate, I worked in a lab that study thermogenesis and we were doing that in animals, but we had this room that was very cold. The whole room was called the guy who I worked for at the time and I'm Harry Carlisle is a very accomplished physiologist. He came from this lineage. I don't know if this literature is still discussed much, but it's a beautiful literature from Rothwell and
Stock. They were the ones who discovered non exercise-induced thermogenesis. The fact that people bounce, who bounced their legs, a lot and move around a lot and have a lot of kind of stochastic movement burn up to 1800 1800 calories more per day than people, who sit more still fascinating incredible. It just incredible. I don't think that worked desert gets as much attention, as it deserves publishing journals like nature, so very fine journalist but in any event
One of the things that I noticed when I started working in that laboratory was that I was cold because the room was cold and dr. Carlyle, Harry said, well, the key is to wear a t-shirt in here for about two or three days and then you will cold adapt. I thought, well, wouldn't I want to put on a hoodie and get warm in there. So I was comfortable. He said, no, actually what you want to do is get yourself, uncomfortably cold activate, your brown fat and indeed, when I did that, I think was just two days of being in that cold environment, then I could come back on the third day, and
Perfectly comfortable because the brown fat had expanded or or added mitochondria or both and I was perfectly comfortable in that environment. I also got very, very lean in those in those days and weeks. Now I've never been somebody who's very lean nor am. I somebody who carries a lot of excess adipose tissue I'm kind of somewhere in the middle. I'm sure I could adjust that with feeding if I want to but it was it was striking, what a powerful effect it had on my entire system of thermal regulation and one of the
The things that I also delighted in when cell reports medicine published your study is they had an accompanying, press release. That went out to those of us that receive press releases. And it described a saying in Scandinavia which is essentially I'm not going to attempt to speak Danish. Even though I have much of my family is in Denmark, a Believer not from Denmark. We have a lot of Danes in my family. I won't embarrass myself by trying to speak Danish as I did before the
Microphones were rolling. But that there's a saying that I think essentially translates to in the fall, when when you're approaching winter, you want to actually wear fewer layers. Not bundle up when you go outside, so that you can prepare yourself for the cold of winter and be able to heat yourself up using your brown fat and that in the spring, as the temperatures are warming. Rather than removing layers, you want to wear more layers in order to be a little bit uncomfortable.
Uncomfortably warm. So that in this heat of the summer, you're better at cooling, your body do I have that right? And maybe do you know the saying and would you be willing to share it? You only the swedes and and Danes will be able to understand maybe the Norwegians to if you don't know what that's
okay. Yeah. So I know that I know that the concept of it because we say it you should you should wear a less before winter and and more before
summer so there it is in English so I do it doesn't have to be esoteric.
Yeah and you're completely right and I think this is the this is just something that we know in the Scandinavian countries. I think that we intuitively know this but if we just go back a little bit in history, I think that's him around the 1950s. The the Russian government went out and said well we should do something about it, took tuberculosis or Pentair, make a epidemic the worse at this time. So they wanted to have the the people
Be more resilient to the cold and also increase our immune system. So in Scandinavia and actually also in Russia. We put our babies outside to sleep in the prom and that is like to also to get more resistant to the cold but also to increase our immune system and we still do that. And then Mark. So
we really. Yeah, we do babies are taken out in the
cold in the snow in Frosty rain. Everything might two boys,
I've been sleeping out in winter, or at least the first many free for five years, because it's like, very good for them, and they get a better immune system and get resilient to the codes. They will have less colds. And also, they run around in a t-shirt when it's super cold because they have activated all their Brown fat. I didn't understand at that time, I must I must say, but I kind of like intuitively also knew because we have inherited this way of doing things with our
Our culture. So and have heard people coming from the US anger, the inside crazy. They put the babies outside and problems and leave them there and then they go inside and drink coffee and the cafe. Well, I
don't think games are crazy. I adore the day and they're, they're amazing culture and people. I'm so fortunate to have family members from Denmark, but I did notice. So when we were in Copenhagen and I know we saw you there not long ago, that was June.
The water in the Harbour was calm was cold. Therefore, even though the Pacific is close to here, which is very cold, felt pretty cold, but it was summertime ish. So people were in summertime mode, right? T-shirts and shorts and things, that that sort, but it did strike me that people in Copenhagen are dramatically fitter than they are in the United States. I mean, first of all, everyone's bicycling everywhere.
R. Yeah, not many people wearing sunglasses, so trying to extract as much Photon energy from the Sun as possible which I support as everyone knows. That's am a big fan of getting Sun but also when we did see swimmers they were swimming in this cold water and like it was nothing and their range in age of the swimmers was what was remarkable. You saw the kind of fit triathlete looking types but also young kids, I really young kids and then people
William there, again, their 70s 80s, maybe even 90s really remarkable vastly different than what you see, if you go to the ocean here in Los Angeles or elsewhere. So, yeah, you Scandinavians are onto something with this. I'd like to take a quick break and thank our sponsor inside tracker. Inside tracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and help you reach your health goals. I've long been a believer in getting regular blood work done.
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If you could give us a little bit of the backdrop about what motivated that study, and then, and then walk us through what you did. You know who the subjects were, what you had them. Do what you measured in as much detail as you would like to share. Because I think it's such an important, you know, even fair to say landmark study because it also explored not just cold, but Sona and the co use of cold and sauna as a way,
To probe metabolism and brown fat and other markers as well. And as you do this, I'm hoping at some point that you might tell us some of the observations that you might have made that interested you that perhaps were not in the paper because that's one of the great benefits of sitting across from somebody who did the work in detail. So yeah, if you could tell us about your study and what you did and what
you discovered, thank you for that question, Andrew. I I love to like also explain a little bit. What did we do? Because when people read this,
Kind of paper, they just see the numbers, they don't see what what happened before that, and human studies are very different from. From my study, my study, you can do a knock out of something and then everything is like perfectly matched and control during human studies is very far different from that because people are different even in the group's. So, yeah, but we, when I started this research in 2016, I did not really know what the brown fat was. So, I started reading up on
On all this. And I was very interested in preventive medicine and also the studies that I did before brown brown fat was also like very much in the preventive side like how can we, that was about something else but the Sweet Tooth and how can we lower our sweet tooth and stuff like that? So but after that I wanted to do something new. So I looked into the brown fat got hired in this, fantastic research group where they it's a cell group. So they mostly did cell studies and they didn't have anyone to do
A human study yet and them, but they really wanted me to do that. So I read upon a lot of research about. How does the brown fat get activated? What have been done already? And I mentioned the paper before with sleeping in the cold, I found that particular paper very fascinating and that was so so we're at that time I was like okay so cold exposure as an intervention of sleeping in the cold. Could be a good thing to go out and say well people do this but
On the other hand, is, first of all, it was already done. That was one thing. But the other thing was like well I wanted to see if we can do it like some kind of activity so we can have people move. Also go and do something do something together or whatever and and the cold made us think about well what about swinter swimming and it was kind of like a bit of a joke in the beginning is like winter swimming. Yes, going to activate the brown fat ride but but, but when we read the literature, we couldn't really find anything.
About activation of the brown fat with cold water, besides hand in a bucket of cold water that really there was already there. So we were just thinking, okay? So it should be very potent activation of the brown fat if its cold water, but very different from cold air. So it was kind of also a new thing we were going into and we knew that we were going to do like a more of a proof-of-concept study at the beginning of it. Because it was like
Winter, swimmers must in theory, activate the brown fat, right? But we kind of didn't really know with, was this kind of stressor too much too little or what will happen, actually. But we had this idea about well, we always say that cold water, winter swimming will activate your metabolism but do what do we know if you do? Does that know, we don't so and while this idea was a little bit fun, fun at the beginning, we kind of accept it. It was like oh,
Let's just try this out but because we didn't have the funding for it was like, okay, let's do a proof of concept study. Let's go with a small number, but enough to see a difference between the groups? So the power calculation of that study is done on what we know from pet-ct scannings of the brown fat. So that's the main outcome of that, of course so. And we wanted to go a little bit small, on the numbers of participants because we wanted to
to dig a little bit deeper into the different mechanisms and also redo some of the days. So I really wanted to do that to see if I can replicate also the findings and that's going to take a lot of a lot of funding, but it's also going to take a lot of time to do it. So the proof of concept was just going small, but looking at different mechanisms, we also took fat biopsies for example and looked at the white fat and see if there was any differences between the groups before and after and stuff like that.
So that's kind of like how it started. And the first year was like a field study for me. So I was not a winter swimmer when I started this. It was just a really know I wasn't at all and I would say I was a bit afraid of the cold myself bit of a cold sissy always cold having big socks on and sweaters and stuff like that. So I was like, I am so comfortable. I'm just like everybody else very comfortable. I like being completely temperature neutral but I started like playing with the store like well.
Well if this is so healthy in theory, I should not pack myself up. I should start not doing that. Yeah. But the first year observation of winter swimmers on the jetty, they kind of joked about is they come onto the new, you need to try this. You cannot study this. Some unless you have tried it and I was like, haha, very funny. Of course I can do that but I couldn't, I read the literature. I understood in theory. What happens when you go into cold water but
I completely understood it when I first tried it the first few times not so funny. It felt painful it was just like running too long after a long break and you and your muscles heard the day after, right? You completely regret that you took that extra
mile. What about what do you say, uncomfortable? You mean uncomfortable when you got in and when you were in or uncomfortable afterwards because I find that on rare occasions, but I should just full disclosure. I
I do deliberate, cold, exposure, every morning, for about a minute to two minutes in a cold plunge. There are days that I miss, but when I'm at home, I do that. And when I travel, I do a cold shower, I do finish with a warm shower. So, and we'll talk about why that's probably not the best idea, but and I've been doing it for some years now on and off. But so, just full disclosure. I'm a devotee and I have family members that hate the cold.
I've gotten into it and are starting to like it, but they don't and I don't necessarily like the experience in the cold water, but I love the way I feel when I get out and I, I'm 100% on that statement about loving it. When I get out occasionally, it feels good to be in there, it feels invigorating and I think I've learned to control the gasp reflex and the hyperventilation. And I just have told myself what we know which is that the forebrain struggles to engage for the first 20 or 30 seconds. But if you can get past that wall,
It's far easier to push through, but when you say that it was really uncomfortable, do you mean the experience of getting in or you also felt lousy
afterward? Yeah. It's and very important to clear that out. I only felt very uncomfortable doing it at the moment but afterwards, the first time I went with with the group and actually my husband was as well because I really want to someone. I knew coming along because it's very normal if you haven't done this before.
You feel a little bit anxious about it didn't? This is shown in studies as well because blood pressure and heart rate goes up in those who are new to this kind of activity. So I was a little bit anxious about it so it was really uncomfortable just doing it but afterwards as soon as I got up, I felt fantastic. And we went into the sauna and I did three rounds because I just loved it. I loved the feeling afterwards because you have all these new transmitters going in your brain and you feel more positive, you feel it. I feel it.
Invigorate, I had so much energy and that like, I could totally see why people would do this to get energy throughout the day because I definitely had that. I didn't have to do three dips to to get that. I think one would be enough and I often do that also. Now today, I do one dip, sometimes I do to a free tips in one round. You can say one day, but often it's like just one or two times a week for me, that is enough to get that energy and to get that,
Posted to feeling. And I think that that is also why I put up my study in that way, I wanted to study the lowest dose, you can say the lowest amount, we can get away with but still see health benefits. So, what I observed there on the jetty was that some did a long time, they were in the water for a very long time, and to me, it seems maybe a little bit extreme.
Could you give me an example of long
time? Well, so maybe they would like really swimming and they could be
20 minutes or half an hour's a long time. That's a long time. And that was like, ice and people who came up. I mean, I just didn't really feel that this is a something that I wanted to go out and recommend to people after my wanted to research
subjects dying either. Because if you're not adapted, I mean, the people, you know, people can do that. Also a 20-minute cold shower or 20-minute cold plunge. I know people do it, but it's probably not a good
idea. No, probably not. It's going to exhaust yourself and ate the make them age 25.
Asked so exactly. That's when you pass that Homedics dress, this the healthy stress level that's what is happening D. Quite opposite is almost chronic stress actually in the cells. Well what happened then was that I found out if I want to have this protocol get through ethical committee I really needed to go like very like Sleek with the not too long and and make sure that they were also very healthy and and to get approval, of course of this study.
But what I did was to to recruit winter swimmers who already have been swimming for two or three seasons and I just observed them. I said I'm not going to do an intervention study yet, I did that after but I wanted to do like a proof of concept where they were already adapted to the cold and then compare them to a match control group, who were matched on on, you can say diet, so where are they vegetarian or not and one of them worse in each
Also they weren't all vegetarians.
No no no just one in each group.
Yes a with all the amazing fish and meat in Denmark. I'd have a hard time being a vegetarian the breads are amazing, the fruits and vegetables to but okay. So there were a couple of vegetarians in each
group. Yeah. 11 in each. Yeah. Okay and they were most, I'm vegetarian.
I have family members are vegetarians. I'm just poking fun. Yeah,
but that would, they were matched on different things so what we usually match them owners also BMI, which
It shows one gender in this study and we would always choose both men and women normally. But we do see that there are different Brown fat levels. Depending on gender are so women have more Brown fat than men really hmm? Hmm interesting. Yeah I think is interesting
deserves study. Yeah. Yeah.
Why I actually think it's interesting because women are also smaller so in size and mass, right? But they also have
Or a refill temperature, especially on hands and ears. And is
that right? That's that's documented that what women do run colder than men. Yeah. And there's a geologically. I didn't say psychological. No, no, we won't. We won't go to the psychological colder. Cold heat, it's different. Something else. That's a different podcast. Yeah,
another time. So women are just colder physically. So on hands and ears, its measured on that and feet as well. So compared to men and men.
Have bigger Hearts than women and they can pump out more lat Perry fellow than in a woman's body so they could be an explanation for the colder hands. For example, thermal comfortable state is also different between genders. So men are more comfortable at 22 degrees Celsius and women are thermal comfortable at 24 degrees
Celsius and this is the thermostat Wars of home have been now validated. Yes,
Study degree celsius, by the way, prior to starting recording. I made the executive decision that we were going to go with Celsius throughout the podcast because the majority of the world uses Celsius. So for those of you that think in Fahrenheit, the internet is your friend in making those conversions vote. So, we're sticking with Celsius. So men tend to be Thermo comfortable at 22 degrees Celsius women at 24. Okay.
Interesting explains a lot about like
Like also some arguments in the homes where men are turning down the heater and women are turning off the heater and they cannot really. So it's really, it's, I'm on both sides here. I understand the men we understand the women, but it's there is a difference there which was also one of the reasons why we had we in this proof of concept. Study shows one, gender. So it was not like only because we wanted to study, man. It was just to see to eliminate all the confounding factors which could have an impact on our results.
So that was one of the reasons but also because we yeah so women have have more Brown fat than men and otherwise we will have to like do for groups or something like that and not having funding yet, we were like, okay, we need to do like just one a group, just a control group and them, and a group who were over to the winter swimmers. So, I recruited winter, swimmers who have been swimming for two to three seasons because I wanted them to be already adapted.
But not going to long in the water so they told me I did a lot of screening here, of course, beforehand and interviews to see him to ask him. How much do you do and how much do you, how long to stay in the water and I monitored, how long did they didn't stay in the water and recruited based on that, they only did like two to three times per week. It seems reasonable for for Denmark at least to do that. And they stayed only in the water for
One to two minutes. So the co-star subsides, very quickly and you will get this activation of your rest and digest system, which is your parasympathetic nervous system. So do the other branch of your order Norm is in nervous system. And you get that activation because you submerge into cold water. And when you do that, you have activation of your diving response and that's going to slow down, the, you can say the consumption of oxygen also in your body and that's
To slow down your heart rate
and I pause you on this cuz I've heard this before that when we get into cold water, shower or immersion, we get this sympathetic autonomic response to increased blood pressure, increased heart rate, release of norepinephrine from the locus coeruleus in the brain, release of adrenaline dopamine adrenaline from the from the adrenals dopamine, presumably within the brain. But that the parasympathetic response is activated. When we put our face into cold water,
Or go underwater and that's a calming relaxation response. So this brings us back to. I don't want to take us off track from you described in the study, but this brings us back to the first question, which is, if I go completely under water for a moment when I start my cold plunge, does that change the physiological outcome as compared to if I just submerge myself up to the neck? And actually, nowadays there seems to be a little bit of a movement online of people, putting a bowl of ice water, on their countertop, and
Merging their face into it. Did you see this? This is start, obviously more and more posts about this. So could you just touch on the what the dive reflex is and why it act, perhaps activates the parasympathetic response this calming response
but also the diving reflex is activated when you submerge into cold water
even just to the neck. Yeah. Or I thought you had to get your face under. I'm not I'm not arguing different, you're the expert. I just want to.
Yeah I haven't really. I haven't read that. I'd just seen that you can act
Bait your diving response as soon as you go underwater with your body. So you don't have to do it with your face as far as I understand. I could, I could be wrong though. Yeah, so when you activate your diving response, you slow down your your oxygen consumption in your body and that is because the body tries to reserve oxygen. So you will not get hypothermic too fast. So it's kind of like a survival
system in your body. So this survival system is very important for us, of course. So that would be activated and because of that you will have to maybe one minute or so I'm that can't be precise on that because maybe also varies a bit in humans. So 1 to 2 minutes, you will have full activation of the sympathetic nervous system, but also the parasympathetic nervous system and that's going to activate, for example, something like serotonin in your brain, which is like also good for me.
Balance and people feeling in mental balance afterwards. They after they go up, so that is like measured on a questionnaires and also measure like on anecdotes, of course, people tell all the time that they feel good afterwards, we need studies on this. So if anyone sitting out there thinking, that's interesting, then please do some studies on that to get more out of that. Yeah,
so you had So You observe these winter swimmers who are done this for a few seasons. Yeah.
Yeah, they're coming around for a new season of winter swimming, and you've decided to recruit them as subjects. They are getting into cold water, climbing down a ladder or jumping into the water up to their neck climbing. Yeah. Okay. Climbing down the ladder into the cuz this done Outdoors. What a fun study to do. My graduate thesis was done under fluorescent lights with no windows in a, in a building that I'm a ton of fun. As a PhD student, I actually lived in the laboratory as a PhD student, I loved it so much, but not something.
To do a PhD by the way, but they're climbing down the ladder. Yeah, getting it up to their neck, staying in, for one to two minutes and then getting out. And how many times a week are they doing
this? So to do this two or three times per week, and for each time they go it's day. They go, they take three rounds of Sophie dips and to sauna sessions. So they start in the cold and they end in the cold
water. Okay, so it's getting for 1 to 2 minutes, then get out and get into the sauna.
Yeah. What is the temperature of the sauna
about 80 degrees
Celsius? Okay. Then how long are they in the sauna? So they
stayed there for 10 to 15 minutes. So depending on if they went two times per week or three times per
week, okay? And then they get back into the cold for a few minutes. Two minutes up to two minutes. Yeah. Okay. Then back into the sauna 15 minutes or so? Yeah. Then back into the cold for a third-round. Yeah. Back into the sauna.
And then, then they're ending on the money back into the cold again and then ending on cold. Yeah. And, and we'll talk about why it's important and none cold, the so-called sobered principle. How cold was the water in this particular given average because I realized its outdoor winter swimming. So it's going to vary depending on wind, chill and things as
well. Of course. So it's a very uncontrolled environment to do this, kind of study them, but I wanted to do something. That was also very close to something people can do.
For free, going out, nature, and use that, and also have the nature, like it's very healthy impact on us. It lowers our stress stress level as well. So by doing, so, I also measured the temperature, every time they went, so I have this graph and it's actually in the winter swimming book. It shows the temperature and then Mark going like from October to April and it's like starts at 12 degrees. I think is around travel to 12 degrees Celsius the water and then it goes down to
22 degrees in on average, in January, and then up again. So it's within the spectrum of very cold water. I was saved from around 15, 15 degrees Celsius and down. But it was actually not colder than like to 24 degrees in on average when it was the coldest. So it doesn't have to be that code to be good enough and enough to activate our metabolism.
And what time of day are the participants doing this?
Cold sauna alternation.
So I think they did this throughout the day, so I didn't control whether they wanted to go in the morning and the afternoon, or in the evening at a time where I set up the study, I wish I was not controlling it in that way. I wanted them to go whenever they had time. And I also think that is the most important message to give out to give to people is when do it, when you have time, it's not if doing it is when you get home from work, and
And it's 6:00 in the evening and this is the time where you are where you can do it, then try out if it's going to impact your sleep or not, if it doesn't impact your sleep, then fine. But you have to try for yourself and find out what works for you. It's the same for coffee, for example, right? Some people can drink coffee in the evening and go to bed and they can sleep. I can't or exercise or exercise. Exactly. So I can't, I can't do that. And that's because the coffee, exercised, Coldwater immersion. It's going to activate
You're a sympathetic nervous system. You have an increase in stress response in your body and that's going to make it really hard to fall asleep. For some people at least, maybe you are super exhausted anyways and then you will just crash anyways. But yeah, but that's the only thing. So I just told them to do this if they can it during the daytime and that's primarily what they also
did and then all along you're measuring Brown fat by way of this infrared camera, right?
Right. So what did you observe in terms of changes in brown fat? How quickly did that occur? And and then, I'd like to ask also about sauna a bit more because earlier you mentioned that you can activate Brown fat with sauna, as well with heat. I'll go to the surface surface of the skin. How long did it take before? You observe significant increases in brown, fat, and was it increased density of my brown fat or distribution? Was it, you know, showing expansion.
From regions throughout the body and maybe you could also touch on some of the changes in insulin sensitivity and
Metabolism. Yeah, very good question. And I didn't mention this before, but besides measuring temperature as an outcome, for brown fat activity, we also did Pit MRI scanning of the brown fat. So this is like the golden standard for measuring Brown fat and it's not very feasible for normal people to get and a pet.
A CT or pet MRI scanning of the brown fat is super expensive. So we had both to see if we could have like a continuous measure of brown fat in humans because that was already not not out there. So I wanted to see during both the experiments all days. But also during day and night, what kind of like circadian rhythm do we have in our Brown fat activity? So that's why I wanted to have that as well.
The PET CT scanning or the pit MRI scanning was to see upon code. Activation stimulation for some hours. Do we have activation, can we see the brown fat in this subject and also during thermal neutrality of thermal comfortable State? How is that activated in each of the
group, of course. So you want to see how comfortable people were away from the cold water and sauna just at different temperature environments. Is that
right? Yes, I was
I measured that. How comfortable are you? I had I made this scale like visual analog scale and ask them. How comfortable do you feel with this temperature and throughout the study days during cold exposure and thermal comfortable day? That had a whole day where just kept them Thermal comfortable to see, do they activate the brown fat? If they are just completely thermal comfortable as good as we could get with that, because we were asking people on a scale from 1 to 10 and 5 being
I'm comfortable. Where are you on the scales? Of one would be very cold and 10 would be super burning hot. Yeah and so that was a way to like try to figure out how do they actually feel also during their studies also measured electromyography so of muscles to see do they shiver during the cooling day? Sometimes people shiver before they know that really shivering so I had interesting.
Yeah so it's our conscious perception of
I might not be the best readout of shiver.
Yeah, well you if you also get adapted to the cold water, you will have less shivering. There will be less. Vigorous, they will be very small. So you wouldn't probably know that you are shivering because it's the steering is so small. And mitochondria in the muscle cells will be so dense that it doesn't need to shiver maybe that much to get, that is thermogenesis going and compared to when you're completely new.
It's too cold, water exposure. You're not adapted, then the body needs to create these. Mitochondria, these energy Fabrics to keep you warm. And that's also what the exercise is in the beginning. But when we measure this, we did see that the winter swimmers were shivering less or having less vigorous shivering when they said I'm cold. So even though they they perception, their perception of the code was pretty similar.
And the into groups and we could see that the activation of the muscles that we measured on with different and more Bakers and the control group were the
subjects, incentivized to be in the study where they paid or anything of that. Sort of, they just happen to like doing cold and sauna. And so that's why they did this
study. Well, they got paid a little bit for it, but not much. And that's how we do this
story. I was just curious. Yeah, yeah, I was just curious.
There might be some folks at Wonder. So so what did you discover in terms of changes? In brown, fat, insulin resistance, or insulin sensitivity, rather and
Metabolism? So what we saw was we had this kind of different measures to see what to try and on Rel what's actually going on when they are already adapted to the cold water, compared to a control group, who was matched on various parameters? We did see that the winter swimmers
Hat, and increase, insulin sensitivity, they produce less insulin on all the experimental days. So, besides from just cooling them and measuring, the brown fat on each of these cooling days. There were two cooling days and one thermal comfortable day, right? So I wanted to measure insulin window, just they were fasting meaning that they hadn't eaten in eight hours before the study day and they were completely
Still not moving just in a bed and we measured insulin during the experimental day just to see how what level are they on a. We could see that the winter swim at had lower production of insulin and they also when they had an glucose drink. So we give them that to see if they test before we enroll them in studies, to see if they have diabetes. For example, and not knowing, for example, that that wouldn't that would like ruin, maybe the study. So we test for that, and
See if they have like a normal curve. So what was this seeing that? Was that the winter swimmers had a faster glucose clearance in the bloodstream so after two hours we could see that they had a lower level and it went the curve went down faster than in the
control group. So despite having lower insulin release they have better blood glucose clearance which is really what you want, what we all seek, right? You know, excessive insulin is bad insulin, being a more or less a chaperone for blood.
Glucose can do all sorts of other things as well, of course, but and having high blood glucose, obviously terrible. Yeah. For cells, especially brain cells. I don't think people realize how toxic high blood glucose is having high glucose history but if you want to kill neurons you make you make their put them in an environment where there's too much sugar. Oh, yeah. Very, yeah, very neurotoxic, I mean that's and their mechanisms like insulin, that buffer that we keep, you know, keep
But because in a reasonable range so that it doesn't happen. I mean I think that's why people will go into insulin emic shock hypoglycemic shock is also possible. So that range in which neurons are happy is not, AB is not a tremendously large range. Incidentally, the range in which neurons are happy and surviving is much greater as one gets colder than when you heat up. I mean that you can basically destroy brain cells by getting too hot for too long. Oh yeah, yeah, you can definitely destroy brain cells.
Permanently by getting too cold for too long, but you have to get really, really cold for a really long
time. Yeah, very interesting.
Yeah, we're thinking about doing an episode on sort of survival of the brain after death, kind of things, which actually happens. You hear about these people who are declared dead and then come back. And there is actually an a lot of cryopreservation type approaches for that. This is any we risk going into the esoteric now. So I'll steer us back to our discussion about your study. But
so, if I do the math,
These subjects are in the cold. Let's say they're doing three rounds of cold for one to two minutes, three, two or three times a week. What were the thresholds that you discovered were important for getting these positive changes in such as reduced blood sugar or clearance of blood. Sugar being more efficient reduced insulin improved Brown fat distribution and density, how much cold exposure do people
Need how much heat exposure do people need in order to extract these benefits?
Yeah, so when we then calculated the numbers together, we can see that this was ended up being 11 minutes in total per week. So not in one session, of course, but they had two to three visits to the water and the stone a. We so when we divide that out, it corresponds to being in cold water 1, to 2 minutes at a time. But also in the Sun, at 10, to 15 minutes at a time and I think this is very
Like also similar to what we see in other studies. When we look, for example, to the observational studies, from The Finnish cohort study from Logan. It Al for example, they published this very amazing paper in 2015. Some results from this Long Core study where they show that that up to 30 minutes in the sauna was healthy. And they, you you lower your risk of cardiovascular disease and that's like the trust her.
Hold, and if you go further than that, then there is not more healthy benefits to gain from that. So, and before that, it's like 19 minutes, then you will have this dose-response relationship up to 19 minutes. That's really in decreasing, your risk of cardiovascular diseases, and I
think we have two per week, 90 minutes per
week and 90 minutes per session now session? Yeah, per session. If we then compare that with
My study which was 10 to 15 minutes per session. Then I think it fits very well with what we call the homeric stress or healthy stress at your exposure to the cells to this kind of like potent, very stressful situation where they increase heat shock proteins in the cells and that will repair the cells. But if you wouldn't overdo it and you go beyond the maybe 30 minutes in the Sona, this observational study from Finland with more than up to
and Sona bathers where they're full of these for 20 years, they see that 30 minutes per session is like enough, and if you go above that, you don't get more health benefits out of it. So I think there's a window where we can say, the healthy stress corresponds to like 10 minutes and think it's, like, recession possession. And it's not it's not much actually, so you don't need to. It shows that you don't have to expose yourself very much to the Heat or very much actually to the cold to get this healthy.
Benefits from going into cold going to heat and have healthy benefits on your cardiovascular system. So I think this is very important. Also message to get out that you don't have to go extreme. You don't have to swim for a half an hour in the cold water. You can go in the water for 1 to 2 minutes per session, but go up to 11 minutes per week in total and for the sauna, my study showed 57 minutes in total per week, and
And if we also didn't divide it out on these two to three days and two sessions, each day corresponds to 10 to 15 minutes. So it's a load Trestle but I think it's good to have that too maybe we can aim for that if people need to have something to aim for and I think and I think it's really good to have that because then you you don't have then you don't overdo it and if you overdo it you exhaust ourselves and that will increase your risk of cardiovascular disease. Also,
I get a lot of questions about this and I did solicit for questions for this podcast on Twitter. And one of the questions that I got was, as one becomes more cold-adapted to the benefit start to wear off, or can people do too much cold exposure? Of course, the answer to that is. Yes, you can become hypothermic but I'm sensing a different answer now, which is if I understand correctly, the threshold is 11 minutes, total per week of deliberate cold exposure divided into two or three sessions of maybe one to three minutes depending on how long somebody stays in.
Now, and then 57 minutes, I want to be careful. Not to round up to an hour, but divide it in two, maybe three 20-minute sessions or so, you know. So one doesn't have to be perfect as long as you get a bump beyond that threshold but I wonder something which is is it the case that if somebody said oh you know, I'm just going to do one 11 minute session per week. That might actually not be as beneficial as dividing it up because
What you told us earlier is that the hormetic response depends on having that cold shock. You actually don't want to become to cold-adapted. I mean, once the blood pressure response drops down. So and minute 45 and 6, you're getting very cold and you're shivering, but your one is not getting the autonomic stimulus that they want. I guess I could liken this to if exercise worked in a way, where it was only the first few minutes of exercise, that really triggered. The adaptation, of course, this is not how it works, but
In fact, probably quite the opposite. But if that were the case then it's not simply the total amount of exercise. But dividing up the the, the sessions into little bouts, where every single time it acts as a stimulus, that seems to be the key here. This is very important because having watched the landscape of this on social media but also in books and generally I think you're the first person to really touch on this, that the goal is not to get so cold today.
That you can sit in for the full 11 minutes in one session where the goal isn't to be able to do an hour of very hot sauna. If you want to, I suppose people could do it for other reasons. But if the goal is to improve these Health metrics. Yeah. Then the idea is to keep the
stimulus. A stimulus, short exact nature. Yeah,
great. Well, this also, I think there's practical feasibility as you pointed out, because getting into a cold shower or cold immersion or natural body water for a couple of minutes has far less
You know, challenging to most people than finding a full morning to go, you know, spend there. But I've never really heard it articulated that the longer sessions might not be beneficial and might actually be detrimental. That's very important. Were there any other observations that you made that did not make it into the paper or that we're kind of in the the margin notes, I'm in terms of psychological
It's or anything of that sort. There was this recent study on soldiers that talked about weight loss. It sort of a controversial study for a lot of reasons, but one of the things they remarked in the paper was that there were a lot of psychological changes improved, buffering against anxiety, they even ripped the men and women. In that study, reported one of the significant effects was significantly, improved sexual satisfaction, of course, they didn't tell us what that meant for these subjects, but as we won't go there. But but a number of subjects
Active improvements. Was there anything that you observed, or took note of in your study that perhaps didn't make the main abstract? But that we should be aware
of. Yeah, there were some. And I'm today, I regret that I didn't measure on sleep. For example. I frankly didn't really think about that when I when I designed the study. So we were very much occupied with the metabolism.
And kind of had the thought, maybe, this could impact Sleep Quality and I wish, I'd just thought I had the thought that. Why don't you just ask them in a questionnaire, but I ask them every morning or every one who's not many - two, just two mornings. Actually, I'm, we measured on, but the winter swimmers told us before I brought them that they had a really good sleep quality, the control group also had that but they told
Told me on the day where we measured the brown fat on on a day and a night. So, if actually two days and two nights and they told me that they didn't, they had a good night's sleep, but they also woke up. So it's just telling me that they also have like a quick wake up. And then they fell asleep again and they went to swimmers is told they have a really good sleep. So it's like an internal, they all say we sleep very well, I sleep very well, so it's anecdotally.
General it corresponds to what I heard in my study but nothing that I measured on which would be fun to do in the future. But we didn't measure on Sleep Quality. That would have been a really good idea to do. They also told me that they were very comfortable when they were cold, they don't mind went to swimmers, don't mind going out. For example in in the cold with the T-shirt they were also less scared of showing their skin. There is
So so one observation.
Yeah so kind of a reduced social
anxiety. Yeah, stable, just so comfortable in the lab. You as you just mentioned before coats on and everybody running around us, very busy and all the other scientist out in the hallway. And also, my supervisor had her office down down the hallway and one of the winter swimmers one day, just got out of bed. After I have been in the study for it, eight hours. We was a long day, right? He
Out of the bed and had his clothes in the bathroom and he went out completely naked. He didn't care, he just went out. It was like, oh
so that's a side effect perhaps ever getting too comfortable with the cold. We're not recommending that. Although in your book you did a dedicated. Some let me start that again. Although, in your book, you dedicated some pages to naked winter swimming or I should say
Naked cold water exposure as opposed to with bathing suit? Yeah. Are there any data on this? I'm sorry, chuckling but I think in most places in the United States, it's skinny-dipping is not is not legal, most public beaches. There are a few in fact, where I my laboratory before moving to Stanford was in San Diego and I at the Salk Institute for biological studies, beautiful building. Incredible science has done their the beach right below that. It's called Black's Beach.
And and it's a no nude beach. And so whenever tourists were heading down the stairway there I would you know, sort of let them know especially if they had kids. I'd let them know, you know? It's and it's a nude beach of a particular of a particular genre. So I give them a little warning about what, what they could expect down below. It's a in any event, those beaches are quite rare in the United States. May be compared to Europe, I don't know. But yeah. So is there anything special about
Clothes list versus closed exposure.
Yeah, I think in that sense we have bit more free with this kind of like but remember, we also had this winter swimming culture for so for hundreds of years and then Mount And The Windsor, the oldest winter swimming clubs that we have especially the one we have in Copenhagen where I did my next study, which we haven't talked about, but, and it's also not published yet. But in that winter swimming club. It's the oldest one we have in, it's huge and they swim naked.
At this facility men and women men and women and they have so NE where they can go in together and they also have a separate Zone has but it's very much, a Danish thing. And and I think it's, I think it's, I think it's good. If people want that and I had it in my book because people want to know if they have to swim with their bathing suit on out. If they can take it off or what's the, what's the difference? Is there any difference in this? And if you ask me there is no difference. If you have your little
Skinny bikini on, it's not going to do any difference to your cold exposure or you're a Temptation. It's not going to do any difference for your benefits of course, but I think that it has something else, it has something to do with how you also. Observe yourself how you're observant your surroundings and it's so sometimes some sense of freedom in skinny-dipping. So I think people in Denmark, who does this, is they do the winter swimming because they feel free when they do, they come home from work.
Go to this club and they skinny dip and they feel like in touch with nature and they have maybe done this the whole life. So this is an old tradition in Denmark in some of the clubs but the newer clubs are coming. They don't stay, don't do, skinny dip. So everyone has bathing suit up. I never skinny-dip because that people around people with phones and taking pictures all the time. So
this different different nowadays.
Everything is recorded. Yeah, and also this this
This old tradition is also fading away because of
that. Yeah, I use on and called at home but when I travel there, there's a Banya. So Russian Banya has hot sauna and cold plunge. There's one in San Francisco called Archimedes Banya and that one is clothing optional. So some people are clothes such as myself and then other people are not and it's co-ed most of the time. I think they have male-female separated evenings or something like that. And then the other Banya is
88. Which is an on Wall Street in New York as an amazing Banya as well. And these are starting to crop up in different cities or maybe they've been there for a long time. And as deliberate, cold exposure, and sauna gets more popular more people are using them, the one in New York, that that Spidey 8 is always closed. And it's interesting because you know, people here naked or skinny-dipping and they might get certain ideas in mind it. Yeah. All these places are very well lit. And they all have a tone of kind of of
Health that it's about really kind of Health and Wellness. I guess the point being that there's no requirement to do one thing or the other, although in the studies that you did obviously, people were close but I did, I did pay attention to those pages in your book. I thought it's interesting that you put some some dedicated passages in your book related to this. And I think it
my publisher wanted that discussion about that was like, okay
well I think
It, you know, it points to a larger theme which is I think for a lot of people who already do these practices there's no shock there. Yeah. For people that do not do deliberate, cold exposure or sauna. I think that, you know, there is this idea perhaps that, oh, you know, these are Traditions that are kind of Fringe or that they're cut. And I just, I want to queue that point because there's so many things that are happening right now. In biomedical, research and Medicine, you know, serious.
Quality. Peer-reviewed studies published an excellent journals, like your paper on things like deliberate cold exposure, sauna the use of particular supplements, natural natural herbs, and supplements. I mean, there's an entire branch of the National Institutes of Health in the United States dedicated, just to the study of supplements and behavioral interventions for health like meditation and breathwork really incredible. Really. Incredible and psychedelics, of course, being something that for a long time was part of a certain community and feel and
Is being frankly adopted by mainstream medicine even Pharma so the times are changing. And so, yes, I think it's important to know that it's perfectly acceptable and encouraged to wear clothing.
Absolutely absolutely yeah, yeah. And one other thing that I wanted to to mention going back to your questions around with there were any observations in the studies which we really maybe haven't discussed yet and maybe it's in
in in the back of the paper and not mentioned that much was one of the winter swimmers didn't have any brown fat when we measured him 00. And in, we do see this in previous studies as well. That some humans don't have any brown fat
was he did he carry a lot of white fat out of post issue was he was he obese?
No, he wasn't. No, he was not obese because that he would not have been in the study then.
Oh, right? Yes, you mentioned this earlier. Forgive me?
And no, no.
He was them. But what I did observe before, I knew that he didn't have any brown for was that during the cooling experiment where I cooled them for two hours before they go into the PET CT scanner, he was not able to control his shivering like the winter swimmers could. So he got he got very cold, very easily compared to the others. So and
Without didn't know what was different about him, but we could all our me and three others were working on the experiment. We were like, okay, what's going on? Because we turn down the temperature but he started like shivering and then we had to turn it up again and it was just all over the place. The temperature is not. It wasn't that controlled like the others was pretty similar protocol. I could just do pretty much the same because they were same size and also same gender, so it was easier.
To like for see what was going to happen. When will they start Shiver? I quickly learned that but with this subject it was just with this volunteer was just very much different and then when we scanned him and didn't find any brown for I I didn't even think about it. So when we scan him and we didn't see anything, I told the pit. See people who like, oh you put up the wrong scanning it
was the technology.
Yeah. It's the technology was like this scanning looked like the thermal neutral day the film.
Notable day where we also scanned them to see if they have any brown fat. So you have made a mistake, I was pretty sure and the reanalysis at and analyze this scanning and they just concluded. Well it discounting was fine, the experiment went. Well it was just that he didn't have any brown fat so he was like but we just in the paper called a brown fat - so he didn't have any and in my studies we will be called and knock out so it didn't have any brown fat.
What the observation with him and I think that would be that's interesting is that he both shivered very early on and didn't regulate his temperatures. Well, he also told me that then, he was like a five on the scale of how comfortable he fell with the cold. And so it was from 1 to 10, and 5 being Thermo comfortable, and 10 being very cold and, and one very hot. So,
On this slyke scale of an up and down and he was like more of an down on this scale than any of the others. It was an observation that I did, what we did see, in his blood samples, also, that his blood samples looked a bit more like the control group. Also, his insulin levels were like the control group, so a little bit higher than the other winter swimmers, and he also had his blood glucose clearance was, not as
The fast as soon as the the other winter swimmers. So he was like an outlier, what we call it. And in the analysis we also had to take him out of the analysis because he was an outlier so the results showing that the brown fat is more efficiently, activated in the winter swimmers is without him having him in that group or it didn't ruin the study. If I tried to put him in as well and didn't it didn't ruin. The results are in
Nothing. But just to keep it more clear. We put, we took him out of the
analysis. Yes. Oh, he was a mutant, a knockout. Yeah, and I'm sure they're out there. Very interesting. So, if you shiver early then, perhaps you have less brown fat to begin with, although it's hard to conclude from one person that's sort of the, the implication there.
Oh, you haven't adapted to the coat so you should build that up. Yeah, right. So in addition to
looking at regulation of blood sugar,
Round fat metabolism, and so on, were there any markers that you examined in the deliberate cold, exposure group, as compared to controls that revealed to you, that deliberate, cold exposure could have additional benefits say, for immune system function, or for any function for that
matter. Yeah, so for we looked at inflammation, of course, we measure the outcome of blood pressure and so on but we also measured aisle six in this.
They just to see also and inflammatory and inflammatory markers. So I all six went up and it also follows with the il-10. So that is like also very known in the literature, so we measured that. And I think it's very important to, to think about the cold exposure to heat exposure as something that then lowers the inflammation in the body. And would, if we can do that, we will have an open door for preventing lifestyle diseases, right? So for
Type 2, diabetes, but actually also for some mental diseases as well. So, as known as depression and anxiety, and also Alzheimer's disease, which are all associated in research. Also newer, research showing that at that inflammation increases the risk of depression anxiety and Alzheimer's disease, neurological diseases. So if we can decrease inflammation in the body, we will decrease our modern lifestyle diseases, but also these increasing me
For diseases that we see in these modern lifestyle times. So, I think that it's, I think it's very interesting that we can go out in nature and we can use these natural stressors, and it don't want to have it sound, very romantic, or anything. It's just, it's just exposure to temperature. Actually, just a cold or to heat. That is kind of twerk our body into a natural state again and reset it where the, the homeostasis the balance has lost a
It. So the body is going to repair itself in that way, and I think it's beautiful that we can do that. Just by changing the temperature of our body. And although people are very scared of doing this because in our times, we have been away from cold away from heat temperature for some for decades. Now, since we isolated our houses better and we are more sedentary, we also save more indoor. We don't move as much so this.
Very modern sedentary lifestyle has made us more temperature comfortable, just neutral. So, no, no wonder. I mean that obesity is increasing. We don't expose ourselves to the Natural stresses that we did earlier on in our environment but also up until maybe the 70s the 60s where we started having more like comfortable Lifestyles, right? And obesity increases in there in the 80s we can see that from
artistic. So I think that if we can take and cold and heat and you mentioned other things also before but of course, exercise is very important here and also a bit of fasting actually because it all increases the Hermetic stress in the body. So it's doesn't have to be other than natural stresses to the body which then could keep us in their Natural Balance. Again,
can we talk about what I refer to as the so Burg principle, which is to end on cold and the reason I called it the
Over principles because in reviewing, oh, by the way, I wasn't a official reviewer of your paper, but, I mean, in reading and reviewing your paper for its after published Contents, I noticed that you had people end on cold and this has been a long-standing debate in the, the deliberate cold. Exposure Community. Should you warm up in with a warm shower afterwards? To get back in the sauna? What should you end on colder? And non Heat and the sober principal says end on cold as I understand it in order.
Order to force your body to heat itself back up and thereby, increase metabolism further still. Is that right?
Yes. So when you, when you end on the cold, you, you force your body to heat up by itself, and that will require that you activate. You keep your brown fat activated and also your muscles, which is a good thing. It's a good collaboration. So keep your thermogenesis up and that's like an an exercise even when you go home. So in that way, you don't have to
Think about your Colt exposure dipping in in your Plunge, open see what it is. As just an exercise that you do for one to two minutes and then there's over. If you end on the code you have an exercise for your body going on for hours afterwards and that's not only on your metabolism, but it's also going to keep your neurotransmitters activated as well and increase that because your body is still cold. So you need that extra those neurotransmitters to activate, the brown fat ass.
Well, so that's going to make your brown fat cells, more efficient and also your muscle cells more efficient, or increasing mitochondria and the cells, which will then generate heat very fast. So if you have done this for a few times so maybe three four, five times and being new to this but I've tried it a few times, you will notice a switch where you like feel that you get easy early warmer and you can keep yourself warmer. And that is also what we shown in my study is that the winter
Most were a physically warmer on the skin, compared to the control group. So they
when they are out of the
cold when they're out of the coat just relaxing and we tested this in on the days where they were sleeping in the lab so we could see that they had a more activation of the brown fat higher temperature. So probably because they also lose heat. They have a higher heat loss to the body compared to the control group because they have a more vascular.
Skin because of the contrast of cold and heat so they lose heat faster from the body during that day. But is that a bad thing? No, probably not, because that's going to keep your brown fat and your muscles a little bit activated, so we you will have to it. It has to work to keep you
warm and I would hypothesize that. It also might lead to some of the subjectively reported improvements in sleep because in order to fall asleep, you need your core body temperature to drop by.
About 1 to 3 degrees. Yes. So it's not just sufficient to be sleeping in a cold room and under the blanket. You also need your body temperature to drop? Yes. And so what you're saying if I understand correctly is that by forcing by ending on cold and forcing oneself to heat up naturally that increases the brown fat stores, which I see as a kind of like the oil in the candle of the Furnace that is thermogenesis and that
In turn leads to increased heat loss which people might think oh I don't want to lose heat from the body. But yet there are times when you want to lose heat from the body, basically, it sounds like what we want is to be a very efficient heating and cooling system. Yes. That it's not about being cold or being hot. It's really about keeping the system tuned. Well, keeping the oil in the candle is brown fat functioning? Yeah. What could I ask one question about Fedor, fasted, is there any rather are there any
Known benefits of doing, deliberate, cold exposure, and, or sauna fasted versus after a meal say, within the last hour or something of that sort. I do might deliver cold exposure, first thing in the morning. So in general, I'm faster because I don't eat until a little bit later in the day. Yeah. But what's known about that and was that looked at in your study I know you measure glucose but that was as a separate test. Yeah. From the
coal away from the code. Yeah, but I also tested
Glucose on the days on the cold so we measured that as well on on the cooling days are specifically on fasting and fed. I don't know. I don't think that I have seen studies specifically on this.
Okay. More science needed. A number of people asked about the use of deliberate cold exposure to offset some of the symptoms of various diseases. Now here, we're not talking about curing disease. We're talking about offsetting symptoms one.
Ian, I've seen quite often is whether or not people with Raynaud's syndrome, this is a syndrome, my high school girlfriend had this syndrome and I'll never forget, we went around a school dance together. And so is the when we first started dating, and she had Ray nodes, which leads to very poor blood flow to the, the the extremities. And, and she was very cold. So, she left to go to the bathroom and warm up her hands in the warm water. And I was left standing there at the dance and people came up to me and asked, you know, why I was there and who
There with. And I kept telling them who I was with and they didn't believe me because they couldn't believe that she would be with me, made total sense. If you knew me at the time, I was, I was way out of my league with her at the time. I like to think of Entry, I caught up but in any case she was in the bathroom for about an hour or so. At one point, I did consider the possibility that she had just left. But indeed she hadn't she warmed her hands back up. But people with Ray notes, suffer from this, from this thing of very, very cold extremities.
Their fingertips will even turn blue, you know, as if they were starting to get frostbitten, it's quite dramatic. And that question gets asked whether or not there's any use of cold to try and increase the elasticity, the plasticity of the, of the small capillaries in vessels by everything. You've described up until now, it seems like that would be a logical thing to do. And in addition to that whether or not people with autoimmune conditions, people with any other time,
Types of conditions are known to benefit from deliberate cold exposure. I'm not aware of any studies but I get asked about this a lot and they were a lot of questions about this for you in the Twitter
feed. Yeah, thank you for those questions and I get them as well on social media. And I have to say that I haven't seen any studies that erected on this outcome and measuring Rhino, it's syndrome. I do know that it's it's not that rare actually a problem, and I know that many women are more men women than men.
Men suffer from this but logically it would help them if they expose their hands too cold. And also he to make the vest it more vascular. But, and I have heard from people saying that it had helped them but also hurt for some others saying it didn't help them. So, studies are needed on this specific topic. I think I hurt my hands when I go into the cold when I don't have this syndrome at all, but I keep my hands above the
Water. You do. Yeah, I do that often. I take a little bit of a swim and then of course, I have to have my hands in the water, but it helps me when I then get back to the daddy. And them take my hands up because then I can stand there for a little bit and get my one to two minutes exposure and then I can go up because then otherwise that would stop me from being in the water enough time that I as long as I would like to so people.
I suffer from having this pain in the fingers and it can be very intense. So just take the hands up a bit from the water and and that's going to help you also boots, never print boots. It's going to help him defeat some people have the hurt feel the pain in the feet and the ankles and that's going to help them also a
little bit. Okay so there is no problem with keeping hands out or feet in neoprene booties it if people feel the need to do that if that's the what the
Pain of the hands or feet is a barrier for people doing deliberate called exposure than it seems it would be okay to do to keep hands out or to keep your feet if yes,
because the new you do get the exposure but of course, hands and feet are very potent places in your body to get a fast activation of your nervous system, of course. But if you can just, you can also just dip them and then take them up. It's going still going to activate that, but you have your full body is covered.
In Cope receptors, you'll have a full activation anyway, so you know,
you are providing very reassuring information to people because I know a number of people that do not like to put their hands in. I find that the more of my body I get in the more comfortable I am cycle. I don't know if it's psychologically and or physiologically, I find that if where there's an interface between the water and the cold, it's most uncomfortable. So I prefer to just get everything under. I keep my head out although I'd these days I've been dunking all the way in and then coming out.
And then dunking. Once more with my head under, before I get out after the plunge, that raises a different question. Now, we're getting into kind of the practicalities of deliberate cold exposure, which I think are important. Sometimes, I'll experience and I hear from a lot of people that they'll get a kind of back of the head headache at the interface of the of the water. You know, when they're in doing cold immersion to the neck, I assume this has to do with blood flow, that there's vasoconstriction right up until the neck. And in the
Region surrounding it. But that maybe there's still blood flow to the head. But do we know what the origin of these headaches is? And again, this doesn't happen for everybody but some people do experience
them. Okay. Yeah, I haven't really heard about that one specifically, so, but I would say that there are different reasons for maybe keeping your head out of the water. And, but it seems like maybe for some that could be a reason for like, just getting like a quick head
down, could go all the way in. Yeah. Yeah, that's what I've started doing to eliminate, I do.
Wasn't getting headaches but I could. I noticed that interface, okay. And I wasn't in the rest of the experience at so much experience of it so much. So I started dunking all the way in. I noticed in some of the photos that you've put out and in your book that you'll sometimes wear a cap. Yeah, while you go in. Yeah, okay.
And well, it comes from different reasons. So, let's talk about some of the physiological reasons. So when you submerge it in cold water up to the neck and Studies have shown, and this is from Denmark.
Daddy's from a piece, would be a hospital that's when you submerge into cold water up to the neck at zero degrees. So sir, °C very cold and you have a decreased blood flow to the brain by around 30 to 40% and make sense because you activate the sympathetic nervous system. And, and therefore, you will have a less blood flow to the brain. Makes you maybe a little bit this year and
proof again that your you need a heart more than a brain. Because when the sympathetic nervous system gets activated blood,
Always maintain to the heart to keep you alive, but obviously taken away from the brain to keep you from thinking that's why it's hard to think when you're
stressed. Yeah, well, the muscles and then and your vital organs need to, you have to be able to run away from that tiger, right?
The rationale makes total sense. And who am I to disagree with Mother Nature?
Well? But yes, so one of the reasons being that you should keep your head out of the water is that you could increase that decrease in blood flow to the brain further. If you
Up the head. So there's this is a very nice paper from from a research group in Canada, where they have, collectively looked at different papers where they compared heat loss in a crew in the papers where they don't the head and compared to, he blows submerging up to the neck to see how much extra heat. Do we lose from our core when we dump the head. So, and I think is very interesting that with you, submerge up to the neck. You have a
Keep Louis of 11% from the body for and when you then also dumped the head you will increase that heat loss rate by 36 percent. So that means I'm not saying that. I'm not I'm not here to say what is right? And what is wrong. I just think that people should know the information so they can for themselves evaluate what is best for them. But if you increase your heat loss rate by 36% from your core, that's going to increase.
Kris you're after drop, which we touch upon Liberty earlier, even further. So that's meaning that you are closer to hypothermia than you are if you just submerge up to the neck. So you should really think about whether this is like something that you want to do. Or if it's just better for you, not to get that cold in your core. The beanie is also because I have a little bit of sensitive ears. So it meaning that if there is wind, and because we swim in the open sea in Denmark, we have a lot of
Our, when our conditions are just very rainy, very windy. And when the temperature is also freezing, you could get this. What is that code? So very cold and lightheaded just from wind. So if you also submerged into cold water and you then get up, you could, you will get a brain phrase immediately. So it is enough to just go up to the neck, wear a beanie to just, not get dizzy also because the heat loss.
Is increased, of course, but it also the blood flow to the brain has decreased. So the beanie will keep you a little bit warmer so you can stay for 1 to 2 minutes. So it's just a way of like getting around some of the conditions also, so people can choose that if they feel their, but it's quite normal to do in Scandinavia where I be any
of it. And so, for those of you are afraid of doing a 2-minute cold shower what. Dr. Silver just described lets you see how she and others aren't?
Football of doing things far harder than that. When the way you describe it with the cold wind and Scandinavia and is quite striking along the lines of covering the head. There's this seemingly. Paradoxical thing of people going into hot saunas and wearing wool caps. You know, if you go to a Banya or you go to a sauna and there are people who are well from Eastern Europe, where typically, or Finland or
Russia or Ukraine or elsewhere, what you'll see is that many of them are wearing wool caps in the sauna, which many people think is to make it hotter, that's actually not the case. It actually insulates. You from the heat environment, the urge the sense of urgency to get out of the hot, sauna is a brain driven mechanism. And so the reason that people wear wool hats in the sauna, is it actually lets you stay in the saw no longer because it takes a lot of heat to the skin. Before you feel that you have cortical have to get
Out whereas when you insulate the brain, you don't get that signal. It's pretty interesting. I've tried this before just by putting a towel over my head in the sauna and you can stay in there much more easily. And for much longer, you know, as we talk about these different stimuli for the hormetic response, the adaptation to stress, you know, it occurs to me that the big ones in our evolutionary history have been light, right? I mean you were talking about seasonal changes. We
No. They're especially as you go up to Nordic countries that are seasonal changes in the amount of Light by time of year, dramatic ones, in fact, less less. So, at the equator, of course, light temperature food movement and it's sort of interesting. And at the same time, perhaps it should have been obvious to us that there are stimuli that our bodies have evolved to adapt to in very powerful ways. And so the idea that temper
ER heat and cold could evoke these tremendous physiological changes that are beneficial for us. Probably shouldn't surprise us at all. I mean, I mean this is why we, I mean these are not as so, esoteric mechanisms. They're actually the foundational mechanisms by which our body, and the bodies of other animals adapt. So I do have a question about the different ways that people could approach deliberate cold exposure. So for instance,
Children I've been to banyas where their kids, you know, six or seven years old with their parents at the Banya and so they're in hot sauna. I'm not suggesting people do this, if they're, if they're not, you know, adapted to it and you know, talk to your parents kids and talk to your kids, parents talk to your doctors, but is remarkable. I mean, children doing sauna from a young age, or deliberate cold. Exposure, are there any data on this and is it safe assuming that, you know, obviously that they can swim and her. They're doing this in a
Tub or shower. And then I'd also like to ask you about, are there any additional male-female? Differences? I know your study focused on men but other Studies have focused on both and you of course are woman and can attest to your own experience with this. So children, men, women differences there, I'm in terms of protocols, is there anything that people should build into the structure of their deliberate cold exposure? That's unique to that.
So, yes, it does.
On cold exposure. So yeah, I think that starting with the question about children, I think that it's important to to think about as children are smaller than adults. So we cannot really completely transfer all the information and the benefits and also protocols for how long and stuff like that to children. We cannot do that because they are just smaller and math and one study that actually improves this
Is a study where they have compared heat loss in children, boys, who were 12 years old compared, to adults men and looked at the heat loss of the core temperature and exposed them to a 1 or 1 or 2 minutes cold exposure. So, emotion up to the neck and what they saw was that the boys in this study, could actually defend the court.
Mature in is same way as the adults could, but they had to use the muscles way faster. So, it means that they couldn't stay for as long and they use more energy to defend their core temperature, compared to the to the adults. But for one minute, it seems that they could actually confirm but they will be colder when the then come out because they are smaller in their Mass to their rate. You're right. So it means that if the
Surface is so large on children and their mess and muscles being smaller to that ratio. It means that they can be in the water less time before they get hypothermic. So just think about that, they are just smaller. They can't defend their temperature for a very long time. But in this study that showed that for up to, I think it was a minute or so they could mean one minute. Yeah,
I'm glad you mentioned hypothermia and smaller bodied people children. I used to do some
Pacific ocean swims in the morning without wetsuits and I dapped it to it pretty quickly and these are fairly long swims and we brought in an excellent swimmer with us. That was interning with me for a while. Is 16 years old at the time and very lean and it wasn't small for his age but he was smaller than us. Then the it was all guys on the swim that day. I'm Sometimes women join us and he got hypothermic
And he's an excellent swimmer and he didn't report feeling overly cold but fortunately we got him to Shore and he did him up again. So he lived I don't think his mother is going to ever let him go swimming with us again. He's thriving in the world. He's a university student now and he recalls that swim. I mean, this is why you always want to Ocean swim with a buddy with people. Yeah, he he became hypothermic his teeth turned yellow. He was Scott, slurring his words, he wasn't making sense. You know, we got him on the shore and he was
You know, drooling and a little semi euphoric and then kind of, you know, it hypothermia is no joke so I think. Yeah so I am really glad that this is coming up because the cold is a powerful stimulus and and I and kids are at a and smaller. Bodied, people are a greater risk of hypothermia, so good reason to approach it with caution. Maybe start with cold showers, get then cold immersion in Stillwater, natural water, and open bodies of water. Of course, we're always going to be more dangerous for other reasons, current
It's and things that sort of thing. Okay, I'm drowning. Yeah, so important note there, what about any additional male-female differences or similarities that we should be aware of and this comes up all the time on social media. Any time I post anything about a study it's what about women because oftentimes there are
differences. Yeah, yeah and there are we we also just talked about the difference in in, in temperature, in men and women. So it means that if we did, we replicated my
The in women, it could be that they would have enough. You can say, cold, exposure, with just nine minutes per week. It could be because they apparently are also just colder. And, and they have increased metabolism in their Brown fat is just to have more Brown fat, it could be but this is just something that I frankly, don't know. But women also do cold exposure, winter swimming with the 11 minutes protocol, I do it myself and
Feel good about it. So I would say that women Also regarding activation of the brown fed, it should be the same in theory, but I don't know if women actually do need to have another protocol when it comes to this rapid cold exposure. I think that it's another question. If we are talking about ice swimming when it comes to, how far can you be in the cold water without getting hypothermic, then that will be differences in men and, and
Female but, but if you do this cold exposure, for a very brief amount of time, which is what I try to talk to battle, talk about what we call, also micro stressing the body to, to increase the homeric stress to healthy stress. Then this is such a short amount of exposure that it's fairly the same. I think, I think women can look at this as a fairly good protocol for the for them as well.
I always say that if you really dread the cold
Old and don't like the cold, then you are a perfect candidate for using deliberate cold exposure. Because the sympathetic aka the stress response will be greater and there by the adaptation to that shorter. One or two minutes is is going to be much greater right? For people that are perfectly comfortable in the cold. It's harder to get it an adaptation response. The same way that if somebody is very strong and they can lift a very heavy weight that that had very heavy. Weight is unlikely to evoke the same kind of seemed
Re of, of adaptive responses if somebody is not quite as strong. So, another reason to keep these exposures relatively short and more frequent than to do longer duration, exposures frequently. However, let's say somebody only had two days a week to do. Deliberate, cold exposure, maybe they don't have access to a sauna, maybe they do. Would you suggest that they get in for 1 or 2 minutes? Then get out then get back in for another couple of minutes, then get
Get out and call that for you know 45 minutes to try and get to that 11 minutes total per week as opposed to getting in for a full five minutes and then getting out and coming back a second time that week. I know this is getting down into the weeds, but these are the sorts of things that I think people really want to know. Because not a lot of people either don't live close to a body of water or don't have a cold plunge that they can do this with although cold shower, apparently works too. So most people live close to a shower
Yeah, as the definitely I think the changes in temperature is what is strengthening your yourselves in the body. So if you can do the short amount of exposure and then get out and get back in, that is kind of you can say strengthen yourselves because you are challenged him them to, to adapt to changing temperatures. So, during one session, you can change this right? You, you can do it. If you are able
To go to cold water but also a Sona, then you just do it that automatically it you will have a change in temperature but you could also do it. What very aiding the temperature and your cold plunge. If you have, if you have a plunger, if you have it open CEO or you have seasoning it Seasons, even you have, we have that in Denmark. So we have four seasons and the temperature is going to vary with that. So we have nature who can just change this for us and we don't have to think about if you have a cold plunge. Well then I would say that changing the temperature is what is going to create this, huh?
Medic stress and also keep yourselves on its toes. You can say because you are tried the body will still be stressed to try to adapt to the new temperature as it seen as something actually toxic to the body, right? It's a small, small piece of toxicity that you are exposing yourself to you, don't have to swallow it, but it's enough that you touch it actually.
Yeah, great great way to frame it.
That brings me back to this idea of circadian. Time you in your study, you didn't control for specific time of day and now I'm realizing that may be a great asset to the whole thing. So we know, for instance, that our bodies go through, pretty dramatic shifts in temperature from the time we wake up our body starts heating up as we wake up and continues to heat until the afternoon and then starts to drop in the later afternoon and then assuming all things are working correctly, that body temperature drops and we sleep. So I could imagine
In that doing deliberate, cold exposure, at different times, just by way of convenience, or by way of intention, could be very beneficial because my body temperature is going to be quite a bit warmer at one time of day versus another. And in that way, keeping the system tuned. And that's really what I keep hearing coming through in, as you explain these data and all these beautiful studies yours and others is that it's not really about getting cold. It's about going from warm to cold and from cold to warm. It's not it. And I love
This idea because I probably said this a hundred times on my podcast in a million times in my life and I'll continue to, which is that biology is not an event. It's a process like these. These metabolic and Thermo regulatory processes are indeed like the Turning of a knob. It's a verb. It's as opposed to a noun and I and so I think if people can internalize that idea that they're going to have a lot more flexibility, a lot, more fun and and get a lot more benefit as opposed to thinking, okay, I need to
To get into X degrees of water for x amount of time on X number of days. Yeah, you know, in a very rigid
way, all the time, you know, how much and how cool them. And I mean it's that it's just like well because we also don't have studies showing exactly if you just keep five degrees in your water. And you do that for a month, then what happens? We may be the future, we will know much more about this and I'm sure it's going to come and I really hope so. But I just think by logically changing that same
Sure, up and down up and down. And you also do that in your water. It doesn't really, it's not that important, what temperature you will have your water then, then just keep changing it going up and down. It could be all up to 12 degrees Celsius, you're going to activate your brown fat anyway. So, I mean 12 and 19 degrees cold air is enough to activate your grandpa's. So maybe we don't have to go as cold as I think. Many people think and putting ice even all the time you don't have to it's not
I don't think it's necessary to, to expose yourself to that cold temperature all the time, but very it a bit.
So keep the system off balance and all the way to keep it tuned. Yeah. You mentioned it. I study, that is more recent or an ongoing that's not published. Or if you're willing could you share maybe some of the data from that findings, from that study with, of course, the cute, everybody that these are not yet published data, so the conclusions could change.
The data could change for that matter.
Yeah. So we haven't analyzed all the data yet and I know from the study that we did publish that, we would need to look more at the data. So I don't really have any results yet that I can share because we are still in very preliminary analysis of this. So I wouldn't know yet what to exactly say about it, but what we looked at was both men and women my friend. So that's that's
coming. Oh that's fantastic. I'm that answer is going to please a
Great number of people and, and Intrigue everybody so well, listen, I want to really thank you for coming here today to talk about your work and the incredible direction that it points to. Because I think that, you know, no one study is definitive but your study really again stands as a landmark in the landscape of exploring, deliberate, cold, exposure, and Heat.
How it can impact and potentially impact our health. Because frankly, they're just haven't been that many high resolution detailed modern studies of this. There have been studies of Sana, there been some studies of cold. There are a lot of groups and Physiology that work on hypothermia and very cold exposure but most of the temperatures used in those days just aren't practical. So first of all, I just want to thank you for doing the work that you've done and for the work that you continue to do. I'm waiting.
With bated breath, as they say to to hear the results of this study that's ongoing on both men and women. So we'll have to have you back to inform us about that soon. And I want to thank you for the incredible public education efforts that you've been doing on social media and it with respect to your book. And we, of course, will put links to all of those things in the show notes captioned. So people can learn from you and can continue to learn from you. We we certainly need more scientists who are both.
Experience with doing hardcore research as it's called and who also do the practices. I think that's a wonderful additional asset. You know you're not just behind a lab coat or bundled up in a down in a down feather jacket as everyone else's getting in the cold. You do these things and that you are so open and generous in the way that you share knowledge, which includes coming here today to share knowledge with me and our audience. Thank you ever so much.
You're very welcome.
Come I am so pleased to be here and thank you so much for inviting me and I could explain my study and I can share some of my insights from from doing that. So I'm very grateful for being here.
Delighted and we'll have to have you back again. Thank you for joining me for today's discussion, all about deliberate cold and deliberate heat, exposure science, and protocols with dr. Suzanne us oberg if you'd like, to learn more about dr. So Berg's research or you would like to learn about the research of her Institute. The so Berg Institute, please see the links in the show notes caption also in the show. No,
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