How Sauna Use Can Impact Brain Health and Longevity Rhonda Patrick, Ph.D
00:00If we have a little bit more time, I want to talk something about a topic that is near and dear to both of our hearts, which is temperature. Um, you know, my journey on the sauna train, right? I was probably the biggest sauna skeptic for many years. Um, not because I didn't love it. I love I've always loved a sauna. I just had a hard time believing that the data were causal, right? I was just like, there's too much healthy user bias in here. Um but you know over the last five years as I've looked closer and closer at the data um while I can't comment on the effect size I think it's very difficult to comment on the effect size from all the epidemiology it's very difficult for me to believe that there isn't a positive effect in terms of at least cardiovascular disease and dementia. Um so that those are my priors. My priors are I'm now in a place where I actually view sauna as an intervention that can help an individual reduce their risk. And for me personally, because I don't really worry
01:00about cardiovascular disease anymore, it's so easy to manage the risk around that otherwise. But dementia is a very difficult risk to manage because, you know, there's fewer things we understand about the causal pathways to get there than we do ASCBD. So, in many ways, I'm in the sauna not just because I enjoy it, not just because it's a wonderful social opportunity to be with your spouse if that's how you choose to do it, but because I'm also banking a little bit on, hey, I want to get some benefit to my brain. So, tell us where you are currently because I you're one of the people who I think keeps up with this literature more than anybody. So tell us if anything has changed in your mind one way or the other both in increasing confidence, decreasing confidence, you know, just just update us on where you are. >> Yeah, I I am still a huge proponent of using deliberate heat exposure to improve your health both cardiovascular and brain. I do think that the physiological mechanisms um are
02:00somewhat in many in in some ways mimicking some aspects of moderate intensity cardiovascular exercise and that is how it is improving cardiovascular health and also a an aspect of that brain health um cardiorespiratory fitness that's been shown there's been not only like observational data but there's been intervention studies looking at endurance getting someone on a stationary cycle and then adding the sauna on top of that and V2 max improvements were greater in individuals that are also doing the sauna right after their training. >> So, um, anything that improves cardiovascular health is going to improve brain health. But there's another aspect to the story here and this kind of dates back to like the origins of my like one of my first biology, you know, experiments I did in um when I was actually a technician at the Sulk Institute before I went to graduate school. And that has to do with the heat shock protein response. And so we do know that heat stress in the form of either hot baths or going into a hot
03:00sauna, infrared sauna, a little different. you'd have to stay in there really long, like a long time to get to get a real heat shock response. But if you're in like a 163 degree Fahrenheit sauna for 30 minutes, we know that heat shock proteins increase about uh 50% over baseline heat shock proteins. >> And what would be the equivalent exposure in steam or water? >> In the water, it's about 104 degrees for 20 minutes, like shoulders down. So you're >> 20 minutes. >> Mhm. Okay. Yeah. About 20 minutes. And then presumably if you're in a hotter dry sauna less time is needed >> presumably. Uh we don't have that data. I'm just quoting the data we that we the empirical data that we have. >> And what tell me more about the IR because there are no questions I get asked more than hey are all the benefits you're talking about which all seem to come from studies in dry sauna are they also applicable to to infrared saunas? to
04:00which the only data I can find is if you're using infrared you actually have to rely on the change in skin temperature to know you've hit the whereas in sa in dry sauna we can look at time and temperature and humidity right like if I know the temperature of the sauna the humidity of the sauna and then the duration that you're in there I know what I know how to measure the effect size we can't do that in IR so we looked at some data that that looked at basically thermal skin change and I I can't remember the number so I don't want to get it wrong it was either five or eight degree increase in skin temperature was necessary to produce similar benefits. What do you do you know about this? >> I so I not that I don't know specifically about that but I do know most of the studies that have been done comparing and there have not been many maybe three or four that I can think of. They have compared a regular hot sauna to infrared sauna at the same amount of time. So in other words the dose is the same. Obviously the temperature difference is pretty vast depending on the study. The hot sauna could be, you
05:00know, 160 or it could be 175 or 180 and the infrared is like 140 or something like that, right? So, a lot of variation in terms of, you know, the temperature of the sauna. If you're looking at there haven't, in fact, there's like one study like the title of something like infrared saunas or like does not mimic cardiovascular effects of exercise or something like that. And that's because at this the given dose, right? If you're just doing like 20 or 30 minutes, it's not going to be the same. Like your heart rate doesn't go up as much. You don't feel as hot because the temperature is not as hot. Now, you will sweat based on a different mechanism. But as far as my take of the literature, it's pretty clear to me that infrared saunas, if you want it to mimic the cardiovascular exercise response, you might have to double that. You might have Yeah. So rather than spending 20 minutes in 175 degree, 180°ree sauna,
06:00you're going to spend 40 minutes. >> Wow. >> Right. So, you're giving up your time >> if that's the kind of sauna that you either have or enjoy. >> Because you if you do, and I've been in infrared saunas many times, if you stay in long enough, >> like you get that you feel hot and you feel that like heart rate going up just like you do when you're in a hot sauna. It just takes a lot longer. Um, now I know you've had Dr. Ashley Mason on this on um on your your podcast. She's been on my podcast as well. I've I'm a we collaborate. >> Is she awesome? >> She's awesome. just love her. >> She's awesome and we collaborate on a variety of sauna studies. She does a lot of she wears a lot of hats and her data looking at, you know, she's a psychologist by training and she looks at depression and she's looking at depression as an endpoint in terms of, you know, these infrared saunas and she's looking at core body temperature increases, right? So people their core body temperature is going up by like almost two degrees and um in th in that case I mean she's got them in an
07:00infrared sauna for like 85 minutes. People with major depressive disorder were exposed to this this device where they're heating heating up their core body temperature by about two degrees and they had an antid-depressant effect that lasted six months compared to a sham control which was also heating people up but not >> single treatment. >> Single treatment. Now, Ashley has gone out and she's done four to eight treatments depending on, you know, the person whether or not they've completed the whole study. Um, and and she didn't have a sham control, but she's got an just phenomenal. >> How do you sham control that? >> So, he so what he did in his study was he had the same device that just got people a little bit warm enough where they were thinking they were getting the active treatment, but it was not didn't hit the threshold >> of two. Yeah. Raising their core body temperature by two degrees. It was a phenomenal study. Um, and this is, by the way, Peter, what got me interested in the sauna back in like 2008 when I started doing it like every day was I was I lived across the street from YMCA and I was going into the sauna in the
08:00morning. It was freezing in Tennessee. And I was going to the sauna in the morning before I would go into the lab to do my experiments. And I was going every single morning and staying in a long time because I was like, you know, I'm like go hard, go home kind of thing. And I love the heat. And it was incredible the effect it was having on my mental health and my ability to deal with stress and anxiety so much that I was like, "This is insane. What's going on? Nothing has changed other than I'm going to the sauna every day before I go and do all my failed experiments." And that's kind of what got me into the whole sauna was actually the effect on my mental health. So, it's kind of fun to go full circle and um team up with Ashley on some of this this research as well. And she's amazing, by the way. and and we've got some she's got some new studies coming out that are really in this whole field of sauna depression I think just she's opening the door. So um that said the effect on the head and you know if you think about like hot tubs, jacuzzi's, right? We're all sitting with
09:00our head out as well, right? And >> uh it's it's it's it's a good question because I agree with you. When I'm in a hot sauna and I'm also on the top and it's like the same deal. I want to get out in 20 minutes. If I stay in too long, I will get a headache. And I I've know my I know my threshold now. I know the temperature and the duration and the amount of water and all that. Like I know all those variables. >> Isn't it amazing how much water you can drink in a sauna? Like I >> I know it's it's >> I worry I'm going to get hyponetriia. I'm like, you got to slow this down then. >> Um, so the interesting thing is is that talking about dementia risk, I talked about heat shock proteins and I I kind of didn't even I like went off on this tangent. Sorry. But the heat shock proteins, what they do is they prevent proteins from misfolding and forming aggregates, right? And so, um, you know, it's it's obviously when you're getting into a hot sauna, you are denaturing some proteins. And so your heat shock proteins are a stress response that's activated to help with the proper
10:00folding of those proteins that were kind of denatured somewhat from the heat that you were exposing yourself to. Well, it turns out the heat shock proteins stay active for a long time and so they end up having this like effect where you're now just improving the folding of proteins in general even after you're out of the hot sauna. Right? So um he there's a lot of animal studies that have been done. I did a lot of studies in worms like many many years ago where you can take amalloid beta 42 inject it into a worm muscle tissue and then activate heat shock proteins and it like prevents the aggregation and it prevents the the muscle sort of paralysis that occurs in these worms. Animal studies have been done looking at amaloid beta and heat shock proteins and Alzheimer's disease. Again it's having a protective effect. Now is that the whole story? No. The cardiovascular effects are also important for brain health in my opinion. Right? You know the data coming out of Dr. Yariel Linen's lab showing that dementia Alzheimer's disease risk is 66% lower in people that are using
11:00the sauna 4 to7 times per week versus just one time a week. Of course, all >> that was at 179 degrees or greater for 20 minutes or greater, right? >> Yeah, like 175 or 179 exact for 20 minutes. Um, now here's where your question comes in and that is like what about the head? And there was another study out of Finland. It was not Yari's lab. It was another professor that I I'm not aware of. But um this study looked at sauna use and dementia risk. And then it sort of it stratified the data based on temperature. And it was protective. Again, people that are using the sauna, again, they're getting a protective effect against dementia. But when people were going extreme, so if they're going above 200 degrees Fahrenheit and they were on average it was like if they're getting to like 212. People do this by the way. This is like you can go on Instagram and see it's not an uncommon thing. >> Their dementia risk was actually increased with that temperature where it was like really hot and my concern is
12:00the head at that high of a temperature. >> I've started wearing one of those um >> sauna hats. >> The sauna hats. >> Yeah. It it and again I don't know why it works. Do you >> um >> it it does it's not logical to me why it's hurting why it's helping rather. >> I don't know. It's it does seem to help. I mean it shields probably some of the heat that you're being exposed to, right? Because there's got to be >> Yeah, I suppose. But it but the fact that that's a net benefit because it's also got to be preventing you from dissipating heat, but >> clearly what it's preventing coming in is exceeds what but but it makes such a difference. >> Um >> those I mean these cultures and >> but I've als I've also dialed mine down a little bit. I used to be consistently going to at least 200 and now I'm like, you know what, honestly, like 185 to 190 is good enough. >> I'm 180. I do 180. >> Well, my wife is going to be very happy if we dial it down to 180 because she she's more >> uh she seems more sensitive to the heat than I am. >> I'm more sensitive to the heat than my husband is as well. I wonder if there's some kind of sex thing where Yeah, if
13:00it's it's definitely like I'm I'm more sensitive to it. So >> So that's great. So but this is important. So, you really think that we could even dial it to 180? >> Absolutely. >> And just totally get the same. >> I mean, the data is showing that. >> Yeah. Yeah. I know. I just You know me, more is better. >> More is better. Not just you. It's it's it's a common, you know, it's go hard, go home, right? Um but I do think with we're talking about a type of stress here, right? >> Yeah. And you have to get it hormetically correct. >> Exactly. Exactly. You know, I I don't know that the 212 and I hope people that are out there doing the 212 or like listening to this because it's too it's too hot. There's no need for it. You're not there's no evidence you're getting added benefit and if anything there's >> potential benefit potential risk that you're getting. >> Exactly. Potential risk downside. I don't you know that's just one study. >> Yeah. Yeah.