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Brett McKay here, and welcome to another edition of the AOM podcast which, since 2008, has featured conversations with the world's best authors, thinkers and leaders that glean their edifying life improving insights without the fluff and filler.
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Now on to the show.
Cold exposure has gotten a lot of attention in the past few years, with people dunking themselves in ice baths for the sake of their health and well-being.
But good news here exposing yourself to heat by sitting in the sauna or even a hot tub might actually be even better for you, not to mention more pleasant.
In his new book Hot Wired How the Hidden Power of Heat Makes Us Stronger, Bill Gifford unpacks the dichotomy of heat, how it can both be a danger and a healer.
We'll see you next time.
After the show's over, check out our show notes at awimp.is slash heat.
All right, Bill Gifford, welcome to the show.
Great to be here.
So you got a new book out called Hot Wired, How the Hidden Power of Heat Makes Us Stronger.
And you take a deep dive into the research about heat and what it does to our bodies, both the good things and the bad things.
You start out the book talking about how a bike race in Wichita Falls Texas, in the middle of August led you to take this deep dive.
What was going on there?
Well, it sounds like a terrible idea, right?
Riding your bike at 100 miles, 100 degrees.
You know I like to have a goal or a challenge.
That sort of then guides my and motivates my training, keeps me accountable, keeps me in shape.
And I picked this one for some reason, I think because I'd always thought that I wasn't good in the heat and that I didn't do well in the heat.
You know, back when I was a mountain bike racer in my thirties, twenties and thirties, I always felt like heat was my like kryptonite.
So I wanted to kind of test that.
And so, yeah, for those who aren't familiar, this race, it's pretty famous.
It's been going on for a couple of decades.
It's a hundred miles.
And it's again in Wichita Falls, Texas.
If you haven't been there, it is West Texas.
It is really hot in August.
And I mean people do get heat sickness and some people have actually died during this race because of the heat.
Yeah, a handful.
The heat is kind of the point.
Weirdly you'd think, well okay, nobody would sign up for this thing, but 10000 people come and do it some years.
It's wild.
The year I did it, 2023, they call it a heat dome.
It was a super hot summer, 100 degrees or more, pretty much all summer long.
And then the day we did the ride, got up to about 107 Fahrenheit.
It was brutal.
Frankly, I was surprised that I made it, and we can talk more about that why.
Yeah, I mean, one of the things you do this book is you talk about the research you did to prep for this race, to see well, what can I do so I don't get heat sickness, so I don't die?
Right.
And you talk about in the book.
The very first thing you note is that heat can either kill us or it can help us.
And let's talk about how heat can kill us first.
How hot is too hot for humans?
Do we know that?
We don't really know.
And it kind of depends.
You know, about 15 years ago some climate researchers theorized that there was a theoretical upper limit past which humans could no longer cool themselves down.
And it turns out that people were actually already getting into trouble at much lower temperatures.
So, for example, when there are heat waves in Europe, you know it'll be like 90 degrees and that to you you live in oklahoma or to me in salt lake city, that seems like a relatively nice day in the summer, not too hot.
So heat tolerance is very variable depending on a lot of different factors.
But the interesting thing that i learned is that it can be trained, it can be altered, so it's not something that's kind of set in stone.
Yeah, and you talk about people in India, kind of a contrast to those people in England where it's like 90 degrees and they're like, oh my gosh, we're dying.
People in India.
They're living in this sweltering.
It's super hot, super humid and a lot of people do fine.
Right.
I'm not saying it's fun, but I did all kinds of crazy research for this.
But I found one big study where they compared temperature and mortality rates across 400 different cities around the world.
They found that each city has an ideal temperature at which mortality is the lowest excess mortality.
So it's not too hot, not too cold.
By the way, many more people die from cold than from heat, like 10 times as many.
That that was a stunning thing to learn because that's not how heat is framed.
Anyway.
So a city like Toronto, the ideal temperature or the minimum mortality temperature is like 66 Fahrenheit.
And then for Tucson, it's like 86.
So there's differences in like basically.
I mean there's differences in like air conditioning, all that kind of thing.
But I think a lot of it comes down to like heat tolerance of these different populations.
Yeah, being used to it.
What happens in our body whenever it does get too hot?
Because it sounds like, from the research you highlighted, it's not so much the temperature outside our body that's the problem.
It's our internal temperature.
Right.
That's what causes problems.
So what happens when our internal temperature gets too high?
Right.
And we generate a tremendous amount of heat, internal heat, metabolic heat, just by being alive.
And then when we do anything, like any activity, it's almost like a car engine.
Your car moves forward a little bit, but your engine is producing like four times that much energy.
So 80% of it is heat. like a waste product of heat.
When somebody gets too hot, it's kind of gruesome.
If you get to a certain point, you get into heat exhaustion territory, which is you feel wiped out, you feel confused, you feel kind of lethargic you might pass out.
So that's heat exhaustion, not usually fatal.
But then the next step is heat stroke.
And that is what it sounds like.
It's a neurological situation.
You can get aggressive.
You can get confused.
You can pass out.
You can have like a seizure.
And as you're unable to cool yourself off as your temperature rises past like 105, 106 degrees 107, you get into a situation where, like your cell membranes don't function as well.
Your cells kind of explode.
You get into organ failure, especially the liver.
And ultimately you die a horrible death.
I mean, it's terrible.
I've spoken to people who have had heat strokes.
I've seen people having, you know, exertional heat strokes and it's, um, It's not pretty.
It's scary, yeah.
But the thing is, you can treat it.
We know a lot more about heat stroke thanks to research in.
The military is a big place where a lot of this research is coming out of, as well as in athletics.
So when someone gets heat stroke, how do you treat it?
And this is really important.
If somebody is in that zone of elevated body temperature confusion, heat exhaustion, heat stroke, you dunk them in a tub of ice water, if you can.
I mean, that's the easiest.
That stops it in its tracks, really.
I went to a road race in Massachusetts, the Falmouth Road Race, seven mile run in August.
It wasn't particularly hot, but I sat in the medical tent with people from the Corey Stringer Institute, which is devoted to this awareness of heat stroke and prevention of heat stroke.
We had runners coming in in various stages of heat illness and we just threw them in the ice tub and they would come around.
Their body temperature would drop, and they'd be okay.
They'd walk out.
Nobody needs to die of heat stroke.
I think that's the takeaway.
That's the takeaway.
And what's interesting about heat stroke?
It can come on, as you said, with this race that you went to, when it doesn't seem that hot outside.
Yeah, suddenly.
Yeah.
Because the issue is.
I mean, one of the reasons why we don't keel over and die when it gets really hot is humans.
We are a species that can cool ourselves really efficiently.
We sweat a lot, but for sweat to work, it has to evaporate.
That's what cools you off.
So you sweat.
And then as the water evaporates.
It takes heat away from your body.
But when you're in humid conditions, you don't get a lot of evaporation.
So you can run a race when it's like 80 degrees outside, but it's really humid.
You can get a heat stroke in that because your body can't cool itself off.
Right.
Falmouth was 70 degrees, 70 degrees and like 90% humidity.
And that length, seven miles, six, seven miles.
So it's like, you know, it could be around an hour, 45 minutes or an hour.
Right. intense effort and your cooling system doesn't have a chance to catch up.
That's why those events are actually more dangerous than a marathon.
But our cooling system is incredible.
It's this incredible gift that I think is one of our fundamental human traits.
I mean, it kind of fueled our rise to dominance, really.
I mean-
Well yeah, because it's allowed us to basically migrate across the entire planet and live in just disparate climates.
And then, I mean, you talk about this too.
We've had the Born to Run guy.
We've had Alex Hutcherson on the podcast talking about why humans are so good at running.
And one of the theories out there is that, well, we're really good at persistence running.
And so the idea is like our early hunter-gatherer ancestors they would just chase gazelle down And we could do it for a long time, because we could sweat and we can keep ourselves cool.
The gazelle couldn't do that.
And so it just eventually had to stop and cool off.
And then that's when we'd go in for the kill.
Right.
So if you think about walking your dog on a hot day in the summer, I mean you can easily outlast your dog, I'm sure, unless your dog is some kind of endurance monster.
But your dog can only cool itself by panting and you're sweating across your entire body, you know, and it's amazingly potent cooling.
I mean, we have these sweat glands that basically just bring water to the surface of our skin and then it evaporates and that takes off a tremendous amount of heat.
It's super, it's brilliant.
What's interesting though, is that and you alluded to this earlier is that you can take two people and put them in the same sweltering conditions, and one person could be completely fine and another person could have a heat stroke.
What's going on there?
Why the difference?
Right, right.
I mean, you know, fundamentally, it comes down to different levels of heat tolerance.
And you know there could be other things going on, like certain medications, antidepressants for example.
It could be like a stimulant.
Anyway, that plays into it.
Somebody could be drunk or hungover, but basically people have different heat tolerance.
And the interesting thing to me is that, like I said earlier, this heat tolerance can be trained.
It can be modified.
So I went to the Corey Stringer Institute at the University of Connecticut.
And it's named after a football player who had passed away due to a heat stroke.
A Minnesota Vikings lineman and his family helped found this institute.
It's dedicated to basically studying heat in athletes and workers.
And so I did a heat tolerance test.
And so basically...
To do that.
They put you in a heat chamber, basically a hot room or a large oven, which is what it felt like, heated up to 100 degrees 40 humidity, put me on a bike and just had me pedal for an hour.
Then they monitored my body temperature and watched that go up and up and up.
Somebody who's heat tolerant, their body temperature will go up and then it will plateau.
If you're not heat tolerant, it'll just keep going up and then eventually you'll get into trouble.
And so mine just kept going up.
So they were like, okay, you flunked.
Yeah.
And then, okay, so it's trainable.
You can become heat acclimated.
And I think anyone who lives in a hot location during the summer has experienced this.
Like here in Oklahoma, you know, in the spring, it's, you know, in the 70s, 60s, it's pleasant.
And then you have that first day that's above 80 degrees and you're like, oh geez, this is unbearable.
This is hot.
It's because you lost your heat acclimation during the winter and the spring.
And then by the end of August it's 95 degrees, but it feels more bearable because you've gotten used to it.
Exactly.
Exactly.
Yeah.
So what insights did you get from this research lab about what you can do to become heat acclimated?
Are there protocols?
Do we know how long it takes to get acclimated to the heat?
Yeah.
So this sort of protocol actually dates back to the gold mines of South Africa 100 years ago.
The mine owners used to think that okay, every black person is heat tolerant automatically because they live in Africa.
Turned out not to be the case and people died.
So they came up with a – heat testing protocol.
And then people who were not heat tolerant.
Basically, the cure or the protocol is deliberate heat exposure over time.
And so they would have these miners go into a tent that's like 95 degrees.
They set up these tents in the hospital, heated them up and these guys would just shovel rocks for an hour.
And they would do that four or five times, test them again.
Then if they were okay, they could go work.
So it takes like four or five sessions of an hour of getting your body temperature up to a certain level.
For me it was going out on my bike ride for a while, get my body temperature up to 1015 and kind of stay there for an hour.
So I did that.
I did that like 10 times as I was training for the Hotter Than Hell 100.
And, you know, I went into the ride thinking, This is like a bad idea.
This is not going to go well.
I was scared.
And then I kind of got out there and got hotter and hotter and hotter.
And like I was fine.
Like I felt great.
I couldn't believe it actually.
Like I built up this heat tolerance by deliberately working out in the heat.
So again, heat tolerance is trainable.
Yeah, I think I should make the point.
I made sure to be safe and monitor my core temperature as I did this.
So I had a little device called a core and it straps to a heart rate strap and it senses and calculates your core body temperature.
So I knew I was never getting into the danger zone.
So it's really important for people who try this to be safe and not overdo it.
And I think this also goes for what we're going to talk about, which is more of the sort of heat exposure by choice, heat therapy, things like sauna.
Yeah.
Something else you talk about is that there are some athletes who are using heat acclimation or heat adaptation not only to prevent killing over in a race or a game, but also just as a performance enhancer.
Yeah.
So you know, as events like the Tour de France or the Olympics get hotter and hotter, heat has started to become and heat tolerance has started to become a huge factor.
And so they've had sort of star athletes and race favorites coming into these events and just completely bonking because they were fit but they weren't heat tolerant, and it's two different things.
And so athletes started training their heat tolerance.
And then they found out that heat training itself actually brings some performance benefits, similar to altitude training.
So your plasma volume increases.
You have more hemoglobin, more red blood cells, more oxygen carrying capacity.
You know, after I did my heat adaptation, after I did the hotter in hell, I went back to Corey Stringer and I did the heat test and it was like a piece of cake.
I was like high-fiving the lab guys and smiling and it was dramatic.
It was a dramatic performance enhancement.
Okay, so heat can be a performance enhancer and it can also have a lot of other benefits.
And that's what the thrust of this book is about.
So heat, yes, it can be bad for you.
It can kill you, but heat stroke is preventable.
You can adapt to heat and heat can actually be a big positive for your body and brain.
Today, we don't really experience a lot of temperature variations.
We've got climate control.
So you can go from your air conditioned house to your air conditioned car.
So let's talk about this.
What are some of the benefits of being exposed to hot temperatures?
Well, I think cardiovascular is one side.
If you're in hotter conditions, your cardiovascular system has to work harder to keep you cool.
There are these things called heat shock proteins at the kind of cellular level.
They're like little maintenance proteins, or one scientist I spoke to called them mommy proteins, because they kind of take care of other parts of your cell, other machines in your cell.
They take care of your DNA.
They kind of clean up age-related damage.
Those get activated as you spend time in hot conditions.
I think it's interesting that people, even though we live in this comfort and I love sleeping in air conditioning I'm not going to lie, but people gravitate towards things like temperature extremes, things like cold plunging and things like saunas.
I think we crave that variation.
Yeah, I mean, humans have been doing that throughout cultures and throughout time.
So the Nordics have their sauna culture, but then other cultures have similar heating therapies that they do, where they voluntarily expose themselves to heat.
Russia has theirs.
Japan has theirs.
In North America or the desert southwest, Native Americans had sweat lodges.
So yeah, I think there is like this human need to experience extremes in temperature because it does something for our bodies.
So yeah, let's dig more into these.
In our minds.
Yeah, we're going to talk about it.
The mind stuff is really interesting.
So let's talk about some of the benefits of heat exposure, voluntary heat exposure.
You mentioned a few.
It helps our heart health.
And we know this because of some studies done on Nordic people who do sauna regularly.
Okay.
Yeah, Finnish.
And this was sort of my gateway to this entire topic.
I'd been, because I'd written two books on longevity I was aware of these really interesting studies from Finland where they looked at it was really a sort of a broad heart health study.
They're trying to figure out why Finnish guys were dying of heart attacks.
And so they looked at a.
In 2015, this cardiologist and some colleagues came along and looked at the data and decided to compare sauna use and outcomes.
And they found that the most frequent sauna users in this group had about half the rate, or 40 the rate of heart attacks and half the rate of strokes and half the rate of mortality, as the guys who used it like once a week.
Weirdly, they couldn't find anybody in Finland who... any of these guys who didn't use sauna.
So the baseline was once a week.
So four to seven times a week did much better than once a week.
It's a huge finding.
There's no drug that does that.
It's a massive effect.
So what does the heat do?
Why do we get that benefit to our cardiac system from heat exposure?
Yeah, it's primarily, it's like light exercise, I think is the best way to describe it.
Your heart rate goes up, your blood vessels expand, your blood pressure drops.
So there's sort of a mechanistic effect on your cardiovascular system.
So that's one aspect.
That's the first level, but I think there's more to it.
I think it may have to do with the fact that you're activating and this is a guy who had worked in this lab in Finland.
This is kind of what they were pursuing.
Sitting in the super hot sauna kind of activates your sympathetic nervous system because it's stressful.
It's the fight or flight.
And then when you get out, that sympathetic nervous system kind of withdraws.
And so they suspect that some of the benefits may have to do with how it manipulates your autonomic nervous system, which I thought was pretty cool.
That is cool.
You also highlight research how sauna use or any type of other voluntary heat exposure can improve liver and glucose health.
What's going on there?
Yeah, that's a tough one.
They did find that it appeared to improve insulin sensitivity and they don't know if that's because it kind of sped up.
You know your heart rate's going, your metabolism is speeding up perhaps.
It's not clear.
But there is some sort of benefit.
We don't know the mechanism.
Yeah, and some of these healthy behaviors like sauna are kind of tied together.
So it's possible that somebody who's using sauna more maybe is healthier to begin with.
We can't discount that possibility, because it's a little tough to sit through a sauna.
But it's also possible that they're doing sauna and they're doing a little bit of exercise together, they're eating better, or whatever.
It's hard to disentangle.
They did find, these Finnish researchers, they did sort of parse that a little bit.
And they did find that the guys and this was all men in this study originally, the guys who exercised and used sauna frequently had the biggest benefit.
So they're the ones that had the 50% drop in mortality.
But the guys who didn't exercise and just did sauna, they had about a 30% drop.
So 30% effect.
So that's still pretty good.
And that tells you that the heat does do something.
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And then you also highlight research that there might be a potential connection between sauna use or hot tub use with our immune system.
Yeah.
And hot tub use is just as effective, by the way.
People love.
Sauna and hot tubs aren't as trendy now, but any kind of heat exposure or heat therapy also infrared has been found to be effective.
I think with the immune thing, that's been something that has been researched actually for decades.
And back in the day, like in the 60s, these German and Scandinavian researchers referred to it as I think they called it hardening.
So by doing the sauna and also the cold which was part of it, people sort of toughened themselves up and were more resistant to infection.
They missed fewer days of work.
And it's not clear why.
That's interesting.
What about?
I think a lot of people use sauna, particularly because they go.
Well, I go to the sauna, I'm going to sweat a lot, so I'm going to detoxify.
Is there anything to this idea that sweating a lot detoxifies us?
Yeah.
I'm going to make people upset and say, probably not.
Officially mainstream medicine will tell you that the only way we detoxify is through our kidneys, through our liver, and not really through our skin.
So if you're sweating things out, you're just kind of sweating out the liquid that's in your cells, the liquid that's in your blood plasma.
So If there's a little bit of like, you know, alcohol from last night, that's going to come out.
But it's not like a primary method of detoxification.
You know, there have been some studies that suggest that maybe we do put out things like heavy metals.
But those aren't very good studies.
I'll put an asterisk by that and I'll say the jury is still out.
It hasn't been well studied.
You know, it might be that heat exposure accelerates the detoxification that your kidneys and liver do.
Perhaps that's a possibility.
Brian Johnson did a sauna protocol for like, I think, a couple of months and then he tested levels of various toxins in his body and also microplastics and those dropped by.
A lot.
But that's end of one.
It's not a placebo-controlled study, randomized study, but he does have access to pretty good testing methods.
So I'll say the question's still open.
Yeah, still open.
So potentially, we don't know.
It does make you feel clean.
And it is a germ, back to your immune point, it's a pretty clean environment.
Like not a lot of germs can withstand 180 degree sauna.
And in fact you know old time Finnish people like I've met Finnish people who were born in a sauna.
Like they would give birth there.
Yeah, yeah.
It was the most sterile room in the house.
That's interesting.
So you mentioned this idea of heat shock proteins.
I've seen this research before.
It's like oh, when you expose yourself to heat, you activate these heat shock proteins and that can be good for muscle recovery and strengthen muscle gains.
Is there anything to that?
Possibly, but I think it has more to do with cellular resilience.
Going back to our heat tolerance conversation, there is a military study where they exposed, I think, mice to repeated intense heat stress, almost like putting the mice in a sauna again and again, and again.
And they tested their heat shock protein levels and they were through the roof.
And they found that these mice were extremely resistant to heat stroke.
So it's a protective mechanism.
I think as far as muscle gains, I think the increased blood flow, I think, plays a bigger role.
And that's why sauna, I think is, in my opinion, preferable as a recovery or as a post-workout tool to a cold plunge.
Well, let's talk about cold plunges because those have been, that's been the rage now.
We'll say like the past five, 10 years, everyone's cold plunging.
You got the cold plunge brother talking about it.
Yeah.
How do you know some guy cold plunges?
Well, he'll let you know that he cold plunges.
And there's all these benefits that are touted increases dopamine, helps with muscle inflammation, reduces inflammation.
But you talk about those benefits are probably overhyped and cold plunges actually might be hurting your gains.
Yeah.
Yeah, certainly in terms of muscle growth, this has been pretty well studied.
And they found that intense cold exposure slows down muscle protein synthesis.
So after a workout they actually did one crazy study where they had guys do leg work or subjects do leg work.
And then they would put one leg in a warm basically leg container and the other leg in a really cold thing.
And then they had them drink a special drink blah blah blah, where they could see what was happening in each leg.
And the warm leg muscle protein synthesis was happening.
Cold leg, it wasn't happening.
So it tells you that you're not getting the muscle gains.
However, you know, it may help with inflammation.
It may... increased dopamine, norepinephrine, all those things.
It does that in the blood.
We're not sure about in the brain because you have to kill the person to test that.
So we haven't done that.
Also, if you're talking about jumping into a cold body of water, you're getting into territory where drowning is not impossible.
If you suck in a big breath of Water because of the shock of jumping in the cold.
I mean, that can be dangerous.
Yeah, the cold plunges for after a workout, well, it reduces inflammation.
It's like, well, if you strength train, your body needs inflammation.
That's what causes your muscles to grow is that inflammation.
Excellent point.
If you eliminate that inflammation, you're just going to kill your gains.
But you do highlight it could be useful.
A cold plunge could be useful if you're an endurance athlete.
It can help with recovery.
And it also just feels good.
You know, going from the sauna to the cold plunge and back again, that can feel great.
And it's okay to just do it.
You know, do the cold plunge and hot sauna together just for that, because it feels good.
But yeah, if you're focused on building strength and muscle mass, maybe just stick to the sauna.
Yeah.
And you know you, you want to go in the cold plunge because you've built up all this heat in your body and, like you know, sitting in a sauna you're hot.
The idea of jumping in a Lake Superior sounds like the best thing you know 40 degrees sounds like the best idea anybody ever had.
And you know, I've done it too.
It's just.
I think the science of cold is is way behind the science of heat.
But you made a great point about inflammation.
Like inflammation is is not always bad, especially in the exercise context.
Inflammation is part of what drives those adaptations, and it's also a healing mechanism.
Yeah.
And the other thing you point out too is when people do cold exposure, they probably get too cold.
They get in a cold plunge that's like 35 degrees when it really needs to be just like 50.
I mean, it doesn't have to be as cold as you think to get the benefits.
Yeah.
This is like competitive cold plunging, right?
Who can do the coldest cold plunge for the longest?
And, you know, it's obviously it's more challenging.
I think, you know, people like it because it's a mental challenge, right?
But yeah, this is very satisfying to learn from some of the experts I talked to that actually the ideal temperature for the physiological benefits is really in the 50s.
Yeah.
I mean, after I read that research about how cold plunging blunts muscle protein synthesis, I stopped doing cold showers after workouts.
But I still do cold showers.
I don't do it for any health benefits.
I just do it because it's sort of like an exercise in willpower.
It's like, all right.
I know this is going to be hard.
I don't want to do this, but I'm going to do it anyways.
So that's why I do it.
Yeah.
Yeah.
Yeah.
And it makes anything else, you know, whatever else you have to do that day seem easier.
Right.
And so, you know, I'll do a cold plunge.
I'm kind of like, oh, God, do I have to do this?
I won't do it alone.
But like if I'm at the sauna with my son, like we like to have a little cold plunge duels.
It's social.
Yeah.
It's a great father-son bonding activity.
Yeah.
Instead of playing catch, do some cold exposure.
So, going back to the heat exposure, getting the benefits of it.
What temperature do you need to get to in a sauna?
And for how long do you need to expose yourself to that temperature to get the benefits we've been talking about?
So this is interesting.
Those Finnish studies, they asked the subjects about how hot was their sauna?
How long did they stay in?
But it was just a one-time questionnaire.
So it's not super reliable.
It did seem that the people who stayed in like 20 minutes at above 100%
I think 176 Fahrenheit did the best.
I mean, having been to Finland.
There aren't any saunas that are cooler than 176.
That's on the cold end.
I'm not sure we can definitively say that there is one protocol and certainly not one protocol for everybody.
However, It does appear that a lot of the benefits that I've talked about and also some of the mental health benefits, so the heat adaptation, the heat shock proteins, those things those happen when your core temperature gets up to 1015 Fahrenheit.
So I think that's like 38 Celsius.
So you have to get up to a certain core temperature.
That's kind of what it's all about.
Gotcha.
And there are ways you can.
You had this device that measured your core temperature.
That doesn't involve sticking up a probe.
Yeah, no rectal probe.
No rectal probe required.
No Vaseline required.
Yeah.
Yeah.
And I did endure the rectal probe a few times.
It's just a thing that they do.
Right.
Yeah.
My sauna protocol, I have a sauna in my backyard and I like to do it.
I get it up to 190 and I'm in there for 20 minutes.
Okay.
Yeah, solid.
That's what it is.
And then if I have friends over for a sauna session, we want to talk.
I'll put the temperature lower and turn it more into a sweat lodge.
So it's like 120.
And it allows us to talk for a long time.
And then we just sweat a lot.
And then at the end, we'll crank it up and get it really hot and then jump into the pool.
Yeah.
You know, I think, going back to our heat tolerance conversation, you know, nobody should jump into 190 degree sauna for 20 minutes out the gate.
Right.
Just pay attention to your sensations and, you know, pay attention to your body.
I kind of go in for I do 10 minutes at first, and then I kind of check in and like okay, am I bored?
Am I too hot?
Am I not feeling it?
Then I'll get out.
If not, stay in a little bit longer.
I kind of stay in past the point when I think about leaving.
So I push that a little bit farther and you have to make sure to give yourself enough recovery.
Don't just go out for like two minutes and hop back in.
You got to let yourself cool off.
Yeah.
I drink a lot of fluids after.
Yeah.
Key and electrolytes by the way.
This is where you know most of us.
You know, in our French fry filled American diets we don't really need a lot of extra electrolytes.
Like we get plenty.
But if you're intensively sweating or if you're doing like hot yoga or the hotter and hell hundred yeah, you need some electrolytes too.
Yeah.
As I found the hard way.
How'd you find out the hard way?
Oh, I went to a sauna festival in Minnesota and I was doing saunas all day long and you know, hanging out, and I had a couple of beers and I wasn't really paying attention to hydration or salt.
And then the next day I woke up and I just kind of felt miserable and I felt achy like I'd run a marathon, like I was just super beat up.
And then I talked to somebody and they were like, oh yeah, like, did you have any electrolytes?
Like, no.
Got to get those electrolytes.
So I didn't drink enough, didn't have enough electrolytes.
Yeah.
And so you also mentioned earlier that you can get these benefits from heat using a traditional sauna, like a Finnish sauna that uses wood or electric stove to heat things up, an infrared sauna, hot tub.
You can get the benefits with any of these things.
So one of the interesting sections that you have in the book.
You talk about the mental health benefits of heat exposure.
And there's some researchers who are using heat exposure as a potential treatment for depression.
This is coming out of a lab run by a guy named Charles Rison.
We've had him on the podcast before.
Oh, have you?
Okay.
Yeah, that was episode number 585.
This is a long time ago.
So, for those who haven't heard that episode and don't know about this research, what do we know about heat therapy as a treatment for depression?
Well, Chuck is great.
He's a real sort of intellectual explorer and he looks at all kinds of things that might sound extreme or kooky.
He's done a lot with like Eastern traditions.
So the heat piece of it is interesting.
He was involved with a study.
I think the first study was in Switzerland and they put these severely depressed people into kind of a heating device.
It's basically like an infrared sauna that you lie down in.
And they heated these people up to, again, 101.5 Fahrenheit.
And they found that basically their depression symptoms were wiped out, cut in half or more, in some cases completely gone.
So really potent effect against severe depression.
Which is that really surprised me, because you know, you think of like a heat wave and really hot weather and people can get kind of grumpy, but this appeared to have this powerful effect against depression.
Do they have any ideas of why that is?
They have some theories.
People who are depressed appear to have a difficult time regulating their body temperature.
In general, like they don't sweat as much, Their body temperature is elevated, so there's something going on with the whole thermoregulation system in these folks.
One theory that these folks are working with is that if you heat up your brain to a certain level, that stimulates a brain region I think it's called the dorsal raphe nucleus to start producing serotonin.
So similar to what a SSRI drug might do.
So that's one possible reason.
Yeah.
If I remember correctly, another theory that Charles put out there is that using the sauna or exposing yourself to heat it is an acute stressor.
When it causes an acute amount of inflammation, it's like exercise basically.
Yeah.
And then it goes away.
And then it goes away.
It reduces inflammation.
Right.
It's sort of like hair of the dog.
I think depressed people, they have a lot of inflammation in their body and in their brain.
So exposing yourself to an acute stressor, it helps dissipate inflammation in the long run.
Right and exercise does the same thing, and exercise also has a potent antidepressant effect, potentially for the same reason.
This IL-6 inflammatory cytokine goes up, spikes and then afterwards it drops and it stays down.
Yeah, that's really interesting.
Yeah.
And then you highlight this, and I think Charles talked about this in our interview.
He says this heat therapy for depression, it doesn't work for everyone.
No.
And I think the reason is like depression can be caused by all sorts of things.
It's not just because your body doesn't know how to thermoregulate or you have inflammation.
It could be other stuff.
So if your depression is caused by something else, the heat exposure is not going to do anything for you.
Yeah, the way they discovered this is really interesting.
Or one way they discovered this.
They found that they were experimenting with this microbe that they found in the soil in like Uganda and they were trying to use it to help build up people's immunity to leprosy.
And it gives you a slight fever, but a fever is kind of a healing mechanism.
And they found that people who had been injected with this microbe were happier.
They got happier really after having this like slight fever, kind of a crazy story.
Yeah.
And you talk about in the book.
You've had a dealt with a melancholic disposition throughout your life.
And that's why I'm a writer, you know?
Yeah.
Yeah.
Same, same.
It's required.
I'm an Eeyore too.
Did a heat therapy do anything for your melancholy?
Oh, it was amazing.
It's actually why I started gravitating towards heat in the first place.
I started going to the sauna in my gym, which was kind of dark dank, not the best, but it was warm and comforting.
I felt good being in there.
I was going through some difficult work stuff.
Prior to that, sauna was not on my to-do list.
And so I kind of took that and was like, hmm, I felt better.
I wonder why.
Then I came along and I met Chuck Rezon and did a little bit of a dive into that research.
And then I actually volunteered to be sort of a guinea pig in a study that he and his colleague Ashley Mason were doing in Colorado.
And basically they stuck me in this infrared sauna, you know, lying in a hospital bed, Again with the rectal probe.
But anything for science.
They heated me up for like an hour and it was totally miserable.
I was like, why did I do this?
I was kind of bummed out.
We did this, and then I hopped in a cold plunge and I kind of went home to the hotel thinking why the heck did I do that?
But then like the next day it was like the skies opened up and the angels were singing.
It was like, I hadn't felt this good in months. couldn't believe it was like euphoric it was amazing yeah that was the thing that drew me to sauna it was the mental health benefits i'd go there i'd have like this natural drive to go to the sauna whenever i was feeling really stressed out yep and that's why i started it and if it helps my cardiac health great and if it helps heat shock proteins fantastic but i do it primarily because it just makes me feel better mentally Yeah, there's something about it.
And I do the same thing.
I go to the sauna place kind of near my house and spend an hour going in and out.
And then I'm just driving home and I don't care.
Like somebody cuts me off.
Don't care.
You know, I can tackle the work things that I've been putting off.
I'm just better to be around.
Yeah.
Afterwards.
It's great.
So I think, when a lot of Americans in particular talk about hitting the sauna or doing heat therapy, we typically talk about it as a biohacking tool.
Like.
Well, I want to improve my heat shock proteins and I want to improve my cardiac health, whatever.
But you argue that taking this sort of like it's a really reductivist view of heat therapy can miss the bigger benefits of heat exposure.
Right.
What can Americans learn from Nordic sauna culture and heat therapy about some of those intangible benefits of exposing yourself to the heat?
Right.
And you know those mechanistic benefits are real.
But I think it comes down to how do you approach, how do you think about time.
And so here we're like, everything we do has to have a purpose and a payoff, right?
It has to have like a concrete okay, I'm doing this and I'm checking this box and I'm taking down my blood pressure and I'm activating my
Heat shock proteins.
I think in more traditional sauna cultures and heat bathing cultures, it's really about taking time to, as one person told me, to slow down.
So you're going to like a third space.
You're not thinking about work.
You're not thinking about status.
You're not necessarily there for the concrete health benefit, but it's just like you're taking time for yourself or to be with your family or your friends and to do something that doesn't necessarily need to be quantifiable or productive.
Yeah.
And in those Nordic cultures, like sanaen is, it's a social activity.
It's social.
Yeah.
I mean the benefits.
I think the social benefits are tremendous, but I think if you're doing it by yourself, it's almost like a meditation.
You're slowing down.
You're away from your phone.
You're away from work.
Yeah, for me.
You know i mostly sauna by myself, but when i'm in there it's like no phones allowed.
Yeah, and i'm just just gonna phone doesn't work anyway.
Right, i've taken my phone in a sauna before and you'll eventually get this warning saying yeah, your phone's too hot, take it out.
But i just go in there, just close my eyes and just really relax and just don't think about things.
But i do think it's an even more enjoyable experience when you can do it with friends.
Yeah, it's nice, It's a good little bonding thing.
You know, there's something about it.
Like we're in this space that is kind of too hot and kind of slightly panicking a little bit where it's stressful, but you know you're together.
So it breaks down inhibitions I find also.
So, like in New York, where people walk around with you know their guard up, these social saunas are hugely popular and you go in and, like you, talk to people.
It's crazy.
Yeah, you mentioned that in that study with the people about depression and sauna treatment.
One of the things they noticed- Yeah, they started talking.
Yeah, people just start talking and they're just yapping.
Yeah.
Yeah.
And you did the same thing.
You just started yapping to this- Yeah, I was just babbling like a madman.
Yeah, that's really funny.
And I'm not the chattiest person typically, but it somehow broke down those inhibitions.
What do your sauna sessions look like these days?
So there's a couple places in town that I go to.
One place is super, super hot.
And so I like debate with the guy like, I think your sauna is too hot.
But anyway.
The cold plunge is awesome.
It's like clean, which is, I think, an important quality in a cold plunge, especially a public cold plunge.
So yeah, it's real basic, right?
One thing I noticed cold plunges and I've been worried about doing cold, like public cold plunges.
Whenever I've done cold plunges, I have to pee.
Like you immediately, like there's some response.
I think there's some response in your body.
Once you hit cold, like you're just like, I need to pee.
Yeah.
Yeah.
So I couldn't imagine doing a public cold plunge.
Cause the only thing I'm thinking is like people probably just ruined it for me, I think.
Right.
Yeah.
I'm sorry.
Okay.
So you do the sauna, you do the cold plunge and how often are you doing, doing this?
Oh, I do like once or twice a week at this point.
So I'm like the control group in those finished studies, you know, but it's enough.
And you know, I, I go when I could take the time.
It's like an hour.
Yeah.
And so in fact, I'm going to try to go today and get my kid to go.
He's home from school.
That'll be pleasant.
So yeah, that's going to be the afternoon.
I go in the afternoon.
I go at like four.
So I'm kind of done with any kind of productive writing I've had to do, because it's so relaxing that I want to go to sleep afterwards.
Yeah.
Yeah, for me, I have a sauna in my backyard.
It's one of the best purchases I've ever made.
That's so great.
It's fantastic.
I go in after a workout for 20 minutes, but it's awesome.
I love it.
Yeah, you know, I feel like I should get one now, but I haven't pulled the trigger.
But, you know, I don't necessarily want to always sit in there by myself.
Yeah, you like the social aspect of it.
Yeah, so maybe that's a trigger for inviting people over and having sauna days.
Yeah, inviting your friends.
Well, if I'm ever in Salt Lake, I'll hit you up.
We can do a sauna session.
Yeah, for sure.
Bill, this has been a great conversation.
Where can people go to learn more about the book and your work?
Yeah, the book is called Hot Wired and I'm on Instagram and the site formerly known as Twitter at Bill Gifford.
I'm also on things like Threads, so you can go there.
Well, Bill, thanks for your time.
It's been a pleasure.
Yeah, Brett, thank you.
Great questions.
My guest today was Bill Gifford.
He's the author of the book Hotwired.
It's available on amazon.com and bookstores everywhere.
Be sure to check out our show notes at awimis slash heat, where you find links to resources that delve deeper into this topic, including a very helpful article we've got that covers the frequently asked questions that people have about how to sauna.
Well, that wraps up another edition of the A1 Podcast.
If you haven't done so already, I'd appreciate it if you'd take one minute to give us a review on Apple Podcasts or Spotify.
It helps out a lot.
And if you've done that already, thank you.
Please consider sharing the show with a friend or family member who you think would something out of it.
As always, thank you for the continued support.
Until next time.
This is Brett McKay, reminding you to not only listen to the A1 Podcast, but put what you've heard into action.
Before you go, here's another episode worth adding to the queue.
In episode number 821 we explore why routines, especially over rigid ones, can actually make life harder, not easier.
We talk discipline without obsession, structure without rigidity, and where real growth comes from.
You can find it at aom.is slash routines.
That's aom.is slash routines.
Go check it out, episode number 821.
