#6: Exposure To Heat And Cold: The 5th Pillar to Live Long and Well

The 5th Pillar to Live Long and Well is exposure to heat and cold (i.e., sauna, cold plunge).  There is strong evidence supporting the idea that exposure to heat and cold can positively affect both longevity and quality of life. This isn't just wishful thinking; it's backed by credible scientific studies.

Practical Takeaways

The great news is that incorporating these practices into your routine is relatively simple and doesn’t require expensive equipment.

Sauna Tips

For heat exposure, spending 15 to 20 minutes in a sauna a few times a week can be very beneficial. While saunas may not be as easily accessible to everyone, many gyms and wellness centers offer them.

Cold Exposure Tips

Cold exposure is even more accessible. You can achieve the benefits with a cold shower or by adding a few bags of ice to your bathtub. Just three to five minutes in a cold environment a few times a week can make a significant difference.

My Routine

For those interested in practical application, I typically start my day with a cold plunge and end it with a sauna session. This routine helps me feel invigorated in the morning and relaxed before bed.

Historical Context

Heat and cold exposure have a long history. Saunas originated in Finland about 2,000 years ago and were used for relaxation and pleasure. The Finns even used mobile saunas during World War II. Similarly, cold exposure has ancient roots, with historical records suggesting its use as far back as 3500 BC.

Sauna Benefits

1. Reduction in High Blood Pressure: A Finnish study with a 25-year follow-up found that regular sauna use significantly lowered the risk of developing high blood pressure.
2. Lower Risk of Heart Disease and Cardiovascular Death: Another Finnish study observed that regular sauna users had a reduced risk of sudden cardiac death and heart disease.
3. Reduced Cognitive Decline: Regular sauna use was associated with a lower risk of cognitive decline and dementia.
4. Improved Mood and Depression: Studies have shown that sauna sessions can improve mood and alleviate symptoms of depression.

Cold Exposure Benefits

1. Soft Tissue Injury Treatment: Cold exposure has a long history of being used to treat injuries like sprains and strains.
2. Improved Exercise Recovery: Studies, including meta-analyses, have found that cold exposure aids in faster recovery after intense exercise.
3. Enhanced Mood: Cold exposure can significantly improve mood, as shown by various 
4. Metabolism Boost: Cold exposure activates brown fat, which helps burn calories and improve metabolism.

Conducting Your Own Experiment

1. Baseline Measurement: Assess what you want to improve (e.g., sleep, mood, blood pressure) and measure it for a week.
2. Intervention: Incorporate either a cold shower or sauna  for 2-4 weeks
3. Reassess: Measure the same parameters to see if there's any improvement

Conclusion
Exposure to heat and cold can help us live long and well. I encourage you to try it out and see the benefits for yourself. The time commitment is modest, and the potential benefits are significant.

Transcript

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Benefits of Sauna and Cold Exposure

Bobby Dubois 0:04

Hi , I'm Dr Bobby Dubois and welcome to Live Long and Well a podcast where we will talk about what you can do to live as long as possible and with as much energy and vigor that you wish , and with as much energy and vigor that you wish . Together , we will explore what practical and evidence-supported steps you can take . Come join me on this very impor tant journey and I hope that you feel empowered along the way . I'm a physician , ironman , triathlete and have published several hundred scientific studies . I'm honored to be your guide . Welcome back everyone who's joined me before and welcome to those who are first-time podcast listeners . Well , today we're going to explore the fifth pillar , and that is exposure to heat and cold , and the great news is these activities can help you live long and well . Now , as another reminder of the pillars we've talked about before , they include exercise , sleep , nutrition , mind-body harmony and social relationships nutrition , mind-body harmony and social relationships . So there is evidence , and it's actually pretty strong , that exposure to heat and cold affect how long we live and how well we live , and these are the goals that we all hope to achieve and I hope you can gain progress in those areas . I like

Take Home Messages

Bobby Dubois 1:45

to start with the take-home messages . First , there are scientific studies in people that are pretty darn good . Now there's more in sauna than in cold plunge , and these studies show benefits from both exposure to heat and exposure to cold , and these include things like improvement in your mood and exposure to cold , and these include things like improvement in your mood , less likelihood of a heart attack and living longer so really important benefits . Now , doing this may only take 15 or 20 minutes in a sauna , or three to five minutes in a cold environment a few times a week , and you don't need fancy equipment or expensive stuff , certainly not for the cold . Cold shower will work , or a few bags of ice from the market in your bathtub works wonderfully Well . There isn't quite as easy a substitute for a sauna , but certainly the exposure to cold is pretty straightforward and , if folks are interested , I typically do a cold plunge in the morning and the sauna before bed , and I'll tell you a bit more about that later . Now , as always , I'm going to be talking about studies that have been done in humans that are of credible evidence , and I'll put links in the show notes for anyone who wishes to take a look at those studies and if you have thoughts about them by all means ? Let me

History of exposure to heat and cold

Bobby Dubois 3:08

know .

Bobby Dubois 3:09

Well , let's begin with some history . Exposure to heat and cold have been around a really long time , thousands of years and they seem to have passed the test of time , meaning people are still doing it , so they must be feeling they get some benefits . Now . Sauna , that originated in Finland and that was about 2,000 years ago and they heated up stones in a fire and they did it back then for relaxation and pleasure . They didn't do scientific studies back then , so it was mostly for how they felt . The Finns were so big on this that in World War II when the soldiers had to go off to battle , they would have mobile tents or bunkers where they would do the same thing . Now sweat baths are in many other cultures , like ancient Rome and Greece and Native Americans . So heat has been around for a long time as a way of affecting how we feel .

Bobby Dubois 4:11

Cold perhaps goes back even longer , maybe 3500 BC , on papyrus documents . Now the ancient Greeks used it for relaxation and socialization , and probably not much different than the hot baths that they might have done there . But cold has a medicinal history as well . So before the Common Era , hippocrates , in the 4th century BC , he spoke about the use of cold for medicinal purposes and how it had analgesic benefits of reduced pain and that over the years it was also used as a treatment for fever , and so there was a long , long history of thousands of years for sauna and cold plunge . But passing the test of the time does not necessarily mean that it works . We need evidence for that and , as my listeners know , I need evidence for that , which is now what we were about to get to .

Bobby Dubois 5:15

Well , before we can dive in the evidence , it's important to at least understand what we mean by exposure to heat and cold . So the typical exposure that happens in studies is either a sauna , and more commonly a sauna , or a steam bath . Now a traditional sauna , what's called a conventional sauna , is pretty hot . It's 160 to 200 degrees with very low humidity , and typically people do five to 20 minutes per session . There's a newer type of sauna , and that's actually what we have is an infrared sauna . Typically the temperatures are lower and it uses infrared light to heat you up and that's about 140 degrees . It's new and certainly they , from a marketing standpoint , will say it's better than the conventional ones , but I'm not necessarily convinced that there's studies to show that's the case . So either one is wonderful . Cold exposure is pretty straightforward you either have a high ice bath or maybe a cold plunge tank or even just taking a cold shower , especially in the winter , and typically cold exposure is sort of between 50 and 60 degrees and the sessions are short , two to five minutes . Now some people do the cryo ones , which use liquid nitrogen or other type of gas , and that's something we'll come back to a little bit later . Okay , so that's what we're talking about .

Bobby Dubois 6:45

So now let's dive into the evidence . And what does the science tell us ? And we're going to begin with exposure to heat , and partly that's because that's where the best evidence is , and then we'll get to the cold later . So most of the studies that have been done , the clinical studies in people have used a sauna , and there's really far less information about steam baths . Now , it's possible that a steam bath provides all the same health benefits , but

Benefits of sauna and the underlying studies

Bobby Dubois 7:17

we don't know because they haven't been studied in quite as rigorous and frequent a fashion . Now , exposure to heat . So let's just say saunas have four benefits , each of which there's pretty darn good evidence of .

Bobby Dubois 7:31

So the first sauna reduces the risk of developing high blood pressure . Now , this was a study in Finland and we'll talk later a little bit about why so many of these studies happened in Finland and they had a 25-year follow-up . So they had about 1,600 men that were in their sort of 42 to 60-year-old frame and none had hypertension at baseline , and so they followed these people up for 25 years and what they found was for people who were using saunas four to seven times a week which is quite often they had a 50% lower likelihood of developing high blood pressure , so a profound impact on one of the most powerful risk factors for a heart attack or a stroke or death . So if you can do something , that's 50% reduction of hypertension . That's pretty powerful , all right . The second benefit is that people who take saunas have a lower risk of heart disease and a lower risk of cardiovascular death .

Bobby Dubois 8:46

Another Finnish study , different study , and they looked at folks that were in the 40 to 60 age range and they followed them for about 20 years and the risk of a sudden cardiac death was significantly reduced in those who regularly did sauna . Now , this was an observational study , so the way an observational study is often done is you take a group of people who do something , in this case sauna . Take another group , the comparison group , that doesn't do sauna , and then you follow them up . It could be for a couple of years , it could be for a decade , it could be several decades , and then you see what happens and that's what these sauna studies that I've mentioned thus far . That's how they've been designed and , as I said , those people who used a regular sauna compared to those who didn't , have lower cardiac problems and hypertension problems and lower likelihood of death .

Bobby Dubois 9:47

Now , as we have talked about and we'll talk about it increasingly in future episodes , a randomized clinical trial is best , which would mean you take a group of people and then you randomly say you're going to do a sauna regularly and you're going to do nothing or not do a sauna , and then you follow these people . The problem is that to see a benefit might take years and maybe decades , and that's a randomized trial that's likely not to be done . It's just too difficult and to ask people to do something several times a week for the rest of their life ask people to do something several times a week for the rest of their life likely compliance would be not so good . So if you do have an observational study where you just look at people over time and compare those that had sauna and those that didn't . There are ways to be more confident that this could be real , because one of the arguments is that the people who do sauna are not the same as the people who don't . You know , they may have more free time , thus they can do a sauna . They may have more money , thus they can buy a sauna or have a gym membership .

Bobby Dubois 10:57

So there are problems with an observational study , but there's something you look at in the results that gives you a little more comfort that it might actually be real , and that's what we call a dose-response relationship , meaning the more you were exposed to it in this case sauna the better off you were . So in these studies there was a dose-response observed , meaning the more often you used sauna , the better you did , and the more time you spent in the sauna , the better you did . So when they compared people who were sort of once-a-week sauna people versus those who didn't , what they found was there was a 10.8% risk of cardiac death if you use sauna about once a week Now . If you doubled that to maybe two or three times a week now , it was below 8% risk of sudden cardiac death , and if you did it four to seven times a week , it was 5% or half of the risk of sudden cardiac death in those people who are regular sauna users versus those who are not . Well , the other way to look at dose response is how long you spent in the sauna on average each time , and so they compared people that were in there for less than 10 minutes , those that were there for 10 to 19 minutes and those that were there for 20 minutes or more 19 minutes and those that were there for 20 minutes or more , and the more time , the lower the risk of these events occurring . So if you were there less than 10 minutes , then a 7% reduction in risk . At 20 minutes , it was up to 50% reduction in risk . So that's a huge improvement . And both of these suggest that the observational studies , which aren't perfect , might be a little more believable because of the dose-response relationship .

Bobby Dubois 12:59

So now the third benefit of sauna and this is a really interesting and important one is that it may reduce the risk of cognitive decline . So once again , another study done in Finland , and they looked at folks who didn't have dementia when they were in their 40s and 50s and such , and they followed them for 20 years . And again , those people who did sauna had a lower risk of cognitive decline . In fact it was a sort of 20% risk reduction if you had one sauna a week and almost a 35% reduction in risk of cognitive decline if you did sauna four to seven times per week . So another study , another dose-response relationship suggesting the sauna has benefits . And finally , there's studies showing that sauna improves depression , and in this study they took a group of people who were depressed Primarily they were complaining about fatigue and loss of appetite and so they randomized them . Some people did sauna and some people didn't , and their routine was a 15-minute sauna five days a week for a month . And even in that short period of time of a month , the people who use sauna had much better mood and they just overall felt better on a number of measures compared to those who don't . So four different potential benefits , with some evidence that strongly suggests that these benefits may be real .

Bobby Dubois 14:40

So of course the question comes in why might this occur ? What are the theories for why sauna might help us ? Well , as folks may know who've been in a sauna , your heart rate goes up and it may double in fact , and that's kind of like exercise , and we know exercise reduces your risk of cardiac problems . We know exercise reduces the risk of cognitive decline , so it's possible that one of the benefits of sauna is merely stressing or exercising your cardiovascular system without actually running around . There are special proteins in the body called heat shock proteins , and it kind of sounds like what they are , which is , if you're exposed to heat , the body releases these proteins and they may have some benefits . So that may be the way sauna helps us . And they've also done studies on inflammation and they looked at various markers , one of which is C-reactive protein , another is fibrinogen , another is your white blood cell count . But anyhow , they measured various things and they looked at several thousand people and when they compared those that use sauna regularly in this case that was quite often so , four to seven sessions per week versus those that were really not sauna users or only one sauna use , there were substantial improvements in inflammatory production . So again , not necessarily convincing , convincing evidence , but another one of the theories as to why sauna on a regular basis might reduce the risk of these various issues .

Bobby Dubois 16:21

Well , most of the studies I've talked about , although not exclusively , came from Finland . And why Finland ? Well , we think of Sweden and Finland and Norway , the Nordic countries as very much popularizing sauna use . And there's something quite unique about Finland , though . As I mentioned before , the people who use sauna , say , in the United States , might have more free time and more money , and what you could be measuring about the benefits has nothing to do with the sauna itself , but you're just measuring the fact that people who are more well off and have less stress in their life , have more free time , do better . Now in Finland there are about half as many saunas as there are people , and basically everybody can take a sauna or does take a sauna , whether you have it at your own home or whether it's in your apartment building and you sign up . Basically everybody in Finland uses a sauna , and so why that's so important is that in Finland you sort of don't have to worry quite so much about sauna use is associated with particular people or particular income levels . It's getting a bit more of a pure look at the benefits of it .

Bobby Dubois 17:42

Now we can't leave the discussion of sauna without at least mentioning the risks . Now , the risk of sauna . It's a pretty safe technique and activity , but , like everything , do talk with your doctor , because there may be something specific about you that you need to be aware of . So

Benefits of cold exposure and underlying studies

Bobby Dubois 18:02

I hope people are excited , motivated , that in fact , sauna may be something to bring into your life . Now , how about exposure to cold ?

Bobby Dubois 18:10

I have spoken to countless people about the benefits of heat and cold and they say , dr Bobby , I think I could do some saunas , I just have to find one or join a gym that has one . But this cold exposure , I just don't think I can do it . It's cold , it's uncomfortable . I don't like the cold and let me tell you , it is uncomfortable , although you do get somewhat used to it . Not that your body is used to it , but your brain gets used to it . Now , why would you want to do something that wasn't totally enjoyable ? Well , you would do it because there are health benefits . And since the whole point of this podcast is to live long and well , I want to give you some evidence that even this exposure to coal , which may not be fun , has benefits . So exposure to cold has a long history of treating soft tissue injuries . So you sprain your ankle or something like that and you put ice on it , and there's been , you know , years and years , decades and decades , probably hundreds of years , of people doing this and many , many studies that show that it's beneficial .

Bobby Dubois 19:23

The second is cold exposure improves exercise recovery . So if you do a long and hard workout whether it's a bike ride or a long walk or rucking or whatever it might be you want to get better fast . You don't want to be sore , you want to be able to feel like the next day when you want to play pickleball , that you're feeling pretty much ready to go , and what they've shown in studies . In fact , there was a meta-analysis which is a summary , and this one had 52 studies in it and folks were in about 50 degree water for 10 minutes or so and what they found was that at 24 hours after significant exercise , people felt much more able to go back and exercise and some of the blood tests that measure muscle breakdown were also better . So that's the second benefit of cold exposure .

Bobby Dubois 20:18

The third is and I notice this every time I use it because it's a pretty immediate effect it improves your mood . So there's a really interesting study done in one of the Nordic countries and people in that country enjoy winter swimming , which is pretty much what it sounds like . They go swimming not in a web suit , they just jump in the really cold water and swim around for some period of time , and so they did a study in October where the people were just thinking about starting their winter swimming , and they took a group of people who were swimmers and exposed themselves to the cold , and then they had a group that weren't swimmers and they compared it to them At the very beginning . The mood that they assessed through questionnaires and tension and fatigue were all pretty much the same between the swimmers and non-swimmers , which is not a surprise because they didn't actually start the swimming process . They then measured them four months later , in January , and the folks that did the cold swimming , their tension level was better , their tension level was better , their fatigue was better and the amount of negative moods had fallen quite a bit . And the people that didn't do the cold swimming , nothing improved or changed for them .

Bobby Dubois 21:37

So again , I'm not sure we all want to jump in Lake Superior or the Atlantic Ocean during the winter , but at least there's some studies that say it really changes your mood . Now , of course , a shorter duration in a cold plunge or a shower or in your bathtub can also improve your mood , and there are studies of doing that simple approach , and what they found is and they did a study where they put people in cold water not nearly as cold as what I was just talking about and they had them in there for about an hour it was probably about 60 degrees and they measured a number of different hormones and chemicals in the blood and what they found was that the dopamine level , which is sort of your happy hormone , went up 250% well over doubling how much dopamine was available and the amount of noradrenaline , which is again a hormone that sort of gets us up and going , increased 500% , meaning a five-fold increase . And there were reductions also in cortisol . So there are hormone changes when you get exposed to cold . That may explain why people's mood comes about . There was also a study that looked at brain connections . So they looked at MRI scans in folks after they had done a cold exposure . Now the people felt better . They felt more alert , they felt active , inspired , less distressed . But they also looked at brain connectivity with an MRI scan and what they found is in some of the areas of the brain that focused on emotion and attention , there were real changes . So now we have a second reason why exposure to cold might make a difference in our mood . So first it's the hormone levels that change and the second is there could be something about brain connections . Now , the last , and something that may be very exciting to people and might actually motivate some people who are otherwise on the fence , is that cold exposure can change your metabolism and burn more calories .

Bobby Dubois 23:51

So we have multiple types of fat in our body , and in another episode we'll talk about that . The cosmetic fat that we worry about in our belly or our legs , and such is one type of fat called subcutaneous fat . There's also the fat that's around our organs , like our legs , and such is one type of fat called subcutaneous fat . There's also the fat that's around our organs , like our liver and our muscle , and that causes inflammation and heart disease , and that's called visceral fat . But there's a third fat called brown fat . Now , brown fat might sound bad , but it's actually really good . We don't have a whole lot of it , but it's helping us to keep warm when we're cold and shivering , and when that happens it burns a lot of calories . So what they found is the people that regularly do cold exposure . It activates the brown fat and you get more of it . So now we have four reasons to potentially take the plunge and expose ourselves to cold .

Bobby Dubois 24:48

A number of folks have asked about cryotherapy . That's where you sort of walk into this shower-like enclosure and they blast you with a very cold gas , which could be nitrogen gas or argon gas or something like that . Now people say they feel better , but it's really not clear at this point what the true health benefits are . There's some studies that suggest it improves mood , but there has not been the type of studies I just talked about related to cold plunge and that exposure . So it may work . There may turn out to be evidence . That's impressive , but for now we don't know . And what we absolutely do know is it's a whole lot more expensive than just doing some ice in your bathtub . Well , when we talked about sun , I raised the point about safety . So we definitely want you to talk with your doctor and start slow .

Bobby Dubois 25:48

Don't sort of jump into really cold water and stay in there for a long time . You will get

My routine

Bobby Dubois 25:53

shivering and you will feel cold , and for me , I often feel chilled for an hour or so after I do it . So what do I do ? Not that this is a science-based assessment , but I've read all the evidence and have tried it out , so maybe it's helpful to learn what I do . Well , when I do a sauna , I feel afterwards quite relaxed . In contrast , when I do a cold plunge , it wakes me up , I feel rejuvenated , awake , and that happy up state can last for hours .

Bobby Dubois 26:30

Now some people say , oh , it's great if you do a sauna and then a cold plunge before bed . Now , when I tried cold plunge before bed , it made me very happy , as I said , but it made me wide awake and now I couldn't go to sleep . So for me , I do cold plunge in the morning , it's about 50 degrees , I stay in for three minutes , and sauna I do cold plunge in the morning . It's about 50 degrees , I stay in for three minutes , and sauna I do in the afternoon or the evening . It's an infrared sauna , it's about 145 or 150 degrees and I spend 20 to 25 minutes . Some people say well , should I alternate hot and cold , first do the sauna , then do the cold plunge , or do the sauna , cold plunge and then back to the sauna again ? Now I have not seen scientific studies that tell us the best ritual to do , and a lot of this is really what is fun for you and will keep you doing it . But for me , I do the cold plunge by itself , and part of that is , I believe or at least it feels like for me that allowing my body to warm up on its own over the course of 10 , 30 , or 60 minutes seems beneficial , whereas if I jump back in the sauna , I think I would undo some of those benefits . But again , that's anecdotal and that's just my

How to test the benefits in yourself (N of 1 Study)

Bobby Dubois 27:50

opinion . Now , what we need to do for you , though , is convince you whether sauna and cold plunge will work for you , and that's our famous N of 1 study . So what's our N of 1 study ?

Bobby Dubois 28:05

Assess something at baseline . What is it you want to improve ? Do you think maybe it's your sleep , your energy level , your general mood , maybe your blood pressure ? And find a way to measure this at baseline . Now , clearly , if it's blood pressure , you have a home blood pressure monitor . You can see what your blood pressure is typically . Blood pressure you have a home blood pressure monitor . You can see what your blood pressure is typically . If it's sleep , many people have an Oura ring or an Apple watch or some watch that measures sleep , so you could look at that , or there's lots of questionnaires on the web that deal with all these things , so you want to do something , ideally quantitative , that you can write down . Do it every day for a week , write down what your baseline is and then choose which of the items you want to do Now .

Bobby Dubois 28:53

It may be the cold plunge , and you're just gonna do cold shower for a minute or two at the end of your shower . It may be sauna . Whatever it is . Go ahead and do it for , say , two to four weeks and then come back and measure the exact same thing and you'll figure out very quickly whether that intervention , that activity , helped you . Now I won't tell you whether you're going to live long , but it will help you about living well , because you'll know whether you're starting to feel better in a number of objective ways , and it only takes about a month and you'll have a lot of information that may be valuable for how you live your life for the rest of the decades and beyond . Okay , we are coming to the end .

Bobby Dubois 30:26

Now let me know if you try the N of 1 with one of these , let me know , either on my website , which is drbobbylivelongandwell . com , and the doctor isn't spelled out , it's just Dr , so it's drbobbylivelongandwell . com , or Instagram , and I would love to hear what you think . And if you like this podcast , please feel free to rate it and review it . That would be wonderful and I always love feedback . So whatever you can share with me , that would be great . I will be sending out newsletters and so if you wish to be on the mailing list and receive those , please just go to my website .

Bobby Dubois 31:10

And now , what are we doing next ? So for the next episode , we will deal with the sixth pillar , which is the importance of social relationships and the evidence that having good , strong social relationships may extend our lives and help us to be even more functional as we age . I hope you'll join us for the next episode on our journey to live long and well . Thanks so much for listening to Live Long and Well with Dr Bobby . If you want to continue this journey or want to receive my newsletter on practical and scientific ways to improve your health and longevity , please visit me at drbobbylivelongandwellcom . That's drbobbylivelongandwellcom .