Latest / Wellness, Actually with Emily Oster & Perry Wilson, MD / What's the deal with cold plunges and saunas?

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What's the deal with cold plunges and saunas? · Wellness, Actually with Emily Oster & Perry Wilson, MD

0:02
Speaker 1: Emily, I have an audio challenge for you. Are you ready,
0:06
Speaker 1: I'm ready, Okay. I want you to listen to this
0:08
Speaker 1: following clip, and your job is just to tell me
0:12
Speaker 1: what's going on here. I don't know if I could
0:19
Speaker 1: do this. However, it is a countdown.
0:25
Speaker 2: Countdown, So Perry, I think this is going to reveal
0:31
Speaker 2: too much about my Internet consumption. But I think that
0:35
Speaker 2: I have seen the video associated with that audio on
0:39
Speaker 2: TikTok wow, and that person is cold plunging in an
0:44
Speaker 2: icy lake.
0:46
Speaker 1: I believe I have once again underestimated your ability to
0:51
Speaker 1: understand the Internet zeitgeist. Emily. You're correct, that is not
0:55
Speaker 1: a lake. It is a tub of some kind that
0:58
Speaker 1: is filled with icy water. But I will say that,
1:02
Speaker 1: being new to exploring the world of social media wellness
1:06
Speaker 1: influencers and looking at a bunch of cold plunge of videos,
1:09
Speaker 1: this is what I took home was this seems terrible.
1:15
Speaker 1: No one enjoys this.
1:18
Speaker 3: I agree.
1:19
Speaker 2: I think that if there are any benefits, it is
1:22
Speaker 2: that you are just so happy to be out and
1:25
Speaker 2: not dead that everything about your life after that seems
1:28
Speaker 2: better because you are not in an ice pit.
1:31
Speaker 1: There's no joy without sadness. Perhaps that is the philosophy
1:34
Speaker 1: of cold plunges. This week, we're going to explore extreme
1:38
Speaker 1: cold temperatures on your body as well as hot temperatures
1:41
Speaker 1: on your body in the form of Sauna's two ends
1:44
Speaker 1: of a bipolar system of stressing the body with temperature.
1:48
Speaker 1: We'll figure out if the data supports whether these things
1:50
Speaker 1: are beneficial or not. Should we dive in?
1:52
Speaker 3: We should dive in.
1:56
Speaker 2: I'm Emily Oster, I'm an economist and a data expert.
2:00
Speaker 1: I'm Harry Wilson, I'm a medical doctor.
2:02
Speaker 2: It's Thursday, February twenty sixth twenty twenty six, and this
2:06
Speaker 2: is wellness actually.
2:07
Speaker 1: Because you're getting a staggering amount of health and wellness
2:11
Speaker 1: information nowadays from every source imaginable, and some of it
2:15
Speaker 1: is awesome and.
2:16
Speaker 2: Some of it is well actually both. Fortunately we are
2:21
Speaker 2: both people who know how to read studies, how to
2:24
Speaker 2: parse the data, and can tell you what's worth thinking about.
2:27
Speaker 3: And what you can safely ignore.
2:29
Speaker 1: But before we dig in, a note that this podcast
2:31
Speaker 1: is for educational purposes and should not be construed as
2:34
Speaker 1: medical advice. We don't know your unique situation, so talk
2:37
Speaker 1: to your doctor for personal health decisions.
2:40
Speaker 2: This week, we're asking what's the deal with cold plunges
2:43
Speaker 2: and saunas? And then we'll get to your question of
2:45
Speaker 2: the week, But first let's do the health news roundup
2:48
Speaker 2: after the break.
3:01
Speaker 1: Now onto the health news of the week, Emily, I'm
3:05
Speaker 1: looking at CDC dot gov measles numbers through last week.
3:11
Speaker 1: Through February thirteenth, there have been nine hundred and ten
3:15
Speaker 1: total cases to date this year twenty twenty six in
3:18
Speaker 1: the United States. There were twenty two hundred and eighty
3:21
Speaker 1: in all of twenty twenty five last year. If you
3:24
Speaker 1: do the math, we're at about three times higher than
3:28
Speaker 1: twenty twenty five, which was a particularly bad year to
3:32
Speaker 1: begin with their measles outbreaks in the majority of states.
3:38
Speaker 1: What are you taking home from the new data?
3:40
Speaker 2: The measles data is really pretty scary.
3:44
Speaker 3: I mean, I think it's worth saying.
3:47
Speaker 2: You highlighted that we are saying more cases than twenty
3:49
Speaker 2: twenty five. Let me give you a what I think
3:51
Speaker 2: is a sharper fact, which is that in a single
3:54
Speaker 2: week in January of this year, we had more measles
3:57
Speaker 2: cases than all but a small hand full of years
4:01
Speaker 2: over the past three decades. And so really this is
4:05
Speaker 2: an unprecedented set of outbreaks.
4:08
Speaker 3: We are likely to continue seeing them.
4:09
Speaker 2: So those numbers that you gave go through the sort
4:13
Speaker 2: of second week of February already. Since those there have
4:16
Speaker 2: been announcements of a reasonably large outbreak at a college
4:19
Speaker 2: in Florida, announcements of the beginnings of an outbreak in
4:21
Speaker 2: Salt Lake City. So we're going to start seeing more
4:24
Speaker 2: of this around. And it is happening for a very
4:28
Speaker 2: basic reason, which is that measles is super contagious. It
4:33
Speaker 2: can live for a very long time on surfaces. So
4:36
Speaker 2: one number is probably useful to put out there is
4:39
Speaker 2: when we talk about diseases in their contagiousness, we talk
4:42
Speaker 2: about a number called are not which is like how
4:45
Speaker 2: many people someone is expected to infect if we kind
4:48
Speaker 2: of had a totally disease naive population. And so for measles,
4:52
Speaker 2: that numbers estimated to be sort of somewhere in the
4:54
Speaker 2: range of like twelve to eighteen. So every case of
4:57
Speaker 2: measles infects another twelve to eighteen p Well, by contrast,
5:01
Speaker 2: for a number like flu, it's a little bit above one,
5:03
Speaker 2: maybe maybe sort of one to two. And so this
5:07
Speaker 2: is just so contagious and when it faces a population
5:10
Speaker 2: with lower vaccination rates, which is what we have, a
5:13
Speaker 2: lot of people are going to get measles, and that's
5:15
Speaker 2: just kind of what's going to happen.
5:17
Speaker 3: That's it.
5:18
Speaker 1: Yeah, there's really no reason to get measles. That's that's
5:22
Speaker 1: the thing that I keep coming back to. I see
5:23
Speaker 1: these stories of kids who've been hospitalized. A couple of
5:26
Speaker 1: children died last year. You know, you can read the
5:29
Speaker 1: statements from families by and large, who even in the
5:33
Speaker 1: face of this, will often say things like, you know,
5:36
Speaker 1: I don't regret the choices I made, and I understand
5:39
Speaker 1: there's some self defense mechanisms at play here, but just
5:42
Speaker 1: to say it out loud, like measles is one of
5:45
Speaker 1: those things that we have defeated by and large, like
5:48
Speaker 1: we won this particular battle. There's no reason to keep
5:50
Speaker 1: fighting it.
5:51
Speaker 2: Yeah, I mean, I think it's just it's just very
5:53
Speaker 2: sad to say, you know, children will die this year measles.
5:57
Speaker 2: Measles mortality rates something like one in a thousand, so
6:00
Speaker 2: there will be kids this year.
6:01
Speaker 3: Who will die of measles who could have not died.
6:05
Speaker 2: And I think when you put it like that, it's
6:06
Speaker 2: just that's just really sad.
6:09
Speaker 3: That's all. Yeah, it's really sad. Okay.
6:13
Speaker 2: Moving on to some appointment news in the federal government.
6:18
Speaker 2: So j Badicharia, former professor at Stanford, economist and doctor.
6:24
Speaker 3: So he's like both of.
6:25
Speaker 1: Us, the perfect mix of you and I.
6:29
Speaker 2: I'm sure he is in charge of the NIH and
6:31
Speaker 2: has now been named as the acting director of the CDC.
6:34
Speaker 2: Jay is known for many things, but one of them
6:37
Speaker 2: is during COVID, he was one of the authors of
6:39
Speaker 2: the Great Barrington Declaration, which in the fall of twenty
6:43
Speaker 2: twenty argued for a more focused approach to COVID, which
6:48
Speaker 2: would have protected the elderly but allowed COVID to spread
6:51
Speaker 2: more widely among healthy people. You got a lot of
6:54
Speaker 2: attention and hate for this at the time. He has
6:57
Speaker 2: now been put in charge of not one, but two
6:59
Speaker 2: major parts of the federal disease infrastructure.
7:02
Speaker 1: Your thoughts, including the part of the federal disease infrastructure
7:07
Speaker 1: that's responsible for containing outbreaks of disease, just to say it. So,
7:11
Speaker 1: let me take issue with one thing you said about
7:13
Speaker 1: the Great Bearrington Declaration, which, as you said, it would
7:16
Speaker 1: have protected older people and let the virus sort of
7:19
Speaker 1: spread throughout you know less vulnerable populations. That was the pitch.
7:23
Speaker 1: I think the reality is protecting older people. You can't
7:27
Speaker 1: just say like, oh, we will protect people. You have
7:30
Speaker 1: to actually demonstrate it, and as all outbreaks have shown us,
7:34
Speaker 1: it's really hard to do that, Like do you try
7:36
Speaker 1: to isolate people? Are you sliding food under the doors
7:39
Speaker 1: of older people's homes and so on and so forth.
7:42
Speaker 1: So you know, I don't think the Great Bearrington Declaration
7:44
Speaker 1: was well thought out. It was primarily ideological, and that
7:48
Speaker 1: seems to be the way this administration works is that
7:52
Speaker 1: they pick an ideology that they favor, and they put
7:56
Speaker 1: people in charge of the scientific apparatuses who believe in
7:59
Speaker 1: that ideology as opposed to people that are behaving like scientists,
8:04
Speaker 1: which is to look at data and to derive conclusions
8:07
Speaker 1: from the observable data.
8:09
Speaker 2: Let me say one thing here where so I know
8:12
Speaker 2: Jay pretty well, and he is a very smart guy
8:18
Speaker 2: who you know, getting back to our measles discussion, I
8:21
Speaker 2: think does fundamentally believe in routine childhood vaccinations, and if
8:25
Speaker 2: you asked him, would say people should get the measles vaccine.
8:29
Speaker 2: So I have what is presumably a somewhat naive hope,
8:33
Speaker 2: but I do think that relative to some of the
8:37
Speaker 2: vaccine rhetoric that we're seeing coming out of the administration,
8:41
Speaker 2: this is a more evidence based voice on some of
8:45
Speaker 2: these pieces. I'm a little worried that the job of
8:48
Speaker 2: being both in charge of the NIH and in charge
8:50
Speaker 2: of the CDC is just too much job for a
8:52
Speaker 2: single person, even an economist.
8:54
Speaker 3: It is.
8:55
Speaker 1: It is a big job. I hope you're right. I'm
8:57
Speaker 1: not going to hold my breath. I think what I've
8:59
Speaker 1: seen from even very smart people in this administration, and
9:02
Speaker 1: I know some of them too, although I don't know
9:04
Speaker 1: Jay is a tendency to cave to the political wins
9:10
Speaker 1: as opposed to the scientific evidence. But we'll see.
9:13
Speaker 3: I guess we'll find out.
9:15
Speaker 1: Speaking of terrible pandemics that may imminently sweep the nation,
9:20
Speaker 1: I'm wondering if you saw this article about a five
9:24
Speaker 1: thousand year old bacteria that was discovered in an ice
9:28
Speaker 1: cave in Romania that just so happens to be resistant
9:32
Speaker 1: to like all modern antibiotics. So, like I've read this book,
9:37
Speaker 1: I'm pretty sure I think we all turned into zombies
9:39
Speaker 1: in the next sixteen to ninety days.
9:41
Speaker 3: Big Michael Crichton wrote like nine versions of this book.
9:45
Speaker 1: Yeah, yeah, all great.
9:46
Speaker 2: This is published in a Frontiers journal. So the discussion says,
9:51
Speaker 2: this bacteria SC sixty five a dot three sounds like
9:55
Speaker 2: a peptide, represents an ancient ice adapted psychic bactor with
10:00
Speaker 2: a dual profile of multi drug resistance and antimicrobial activity,
10:05
Speaker 2: highlighting ice caves as under explored reservoirs of ancient resistomes
10:09
Speaker 2: and bioactive traits.
10:10
Speaker 3: I felt like when I read that, I was like, man,
10:12
Speaker 3: let's maybe not.
10:13
Speaker 2: Explore more, maybe over explored more or less leave the
10:18
Speaker 2: ice caves where they are. So is I mean, realistically,
10:21
Speaker 2: should we be concerned about ancient bacterias coming out of
10:24
Speaker 2: the explored ice caves.
10:27
Speaker 1: I think there's a theoretical concern. The authors actually in
10:30
Speaker 1: that paper they're quite positive. They're like, oh, we can
10:33
Speaker 1: learn new ways that bacteria develop antibiotic resistance that we
10:37
Speaker 1: hadn't thought of, and thus we can create new antibiotics.
10:40
Speaker 1: So there's always there's always value here. You do have
10:42
Speaker 1: to be careful. I mean, the truth is that there's
10:44
Speaker 1: permafrost all over the Earth that contains ancient organisms, some
10:50
Speaker 1: of which are capable of infecting humans, and some of
10:52
Speaker 1: which haven't infected humans for thousands of years, but nevertheless
10:56
Speaker 1: can persist under the ice, and some of that ice
11:00
Speaker 1: receding right as the as the climate warms, and so,
11:03
Speaker 1: you know, there are a lot of ways that new
11:05
Speaker 1: pathogens can get into the human population. The most common
11:09
Speaker 1: is we, you know, invade the territory of some animal
11:11
Speaker 1: that we haven't had a lot of interaction with, and
11:13
Speaker 1: some virus in that animal or vectory, and that animal
11:16
Speaker 1: hops into humans. That's, you know, probably what happened with
11:18
Speaker 1: All the Stars viruses like COVID and any number of others,
11:23
Speaker 1: as well as several Michael Crichton books. But you know,
11:25
Speaker 1: ice ice melting is another potential vector here. It's definitely
11:29
Speaker 1: something that we should be aware of, but probably not
11:32
Speaker 1: freak out about.
11:33
Speaker 3: Okay, I think that's it for the health news.
11:35
Speaker 2: I feel like next week we need to go have
11:37
Speaker 2: more Olympics because I miss the discussion of condoms.
11:40
Speaker 3: I would rather discuss Olympic condoms.
11:42
Speaker 1: We could discuss. We should kind of have a running
11:44
Speaker 1: like how many condoms have they used now? And let's
11:47
Speaker 1: just have that number exponentially rising, I assume as we
11:50
Speaker 1: get closer to the end.
11:51
Speaker 2: So with that first a break and when we come back,
11:54
Speaker 2: cold plunges and saunaus.
12:02
Speaker 1: All right, we are back, and it's time to talk
12:05
Speaker 1: about your hot and your cold. You know, Katie Perry
12:08
Speaker 1: is on my mind this week because we're talking about
12:11
Speaker 1: cold plunges and saunas. Both of these things are all
12:17
Speaker 1: over the wellness space. You've got promoters on all sides.
12:21
Speaker 1: As I've explored this, I've seen people making claims from
12:26
Speaker 1: the idea that they're a nice way to relax after
12:29
Speaker 1: a workout, to they will improve diabetes control. I mean,
12:33
Speaker 1: it is all over the map. Lots to dig into here,
12:37
Speaker 1: but Emily, before we get started, I feel like we
12:39
Speaker 1: need to just kind of define our terms. Can you
12:42
Speaker 1: walk us through, like what is a cold plunge? What
12:45
Speaker 1: is a sauna? All right?
12:46
Speaker 2: So generally, and I will say, part of what's hard
12:49
Speaker 2: about this space is that this is not well defined
12:52
Speaker 2: because really we're talking about a lot of things, many
12:55
Speaker 2: of which are done in the wellness space, which is
12:58
Speaker 2: an unregulated vague.
13:00
Speaker 3: But when people talk about.
13:01
Speaker 2: Cold plunges, they are generally referring to being in a
13:06
Speaker 2: some body of water largely submerged for an amount of
13:11
Speaker 2: time that varies from like I jumped in the water
13:15
Speaker 2: and I got immediately out to sitting for you know,
13:18
Speaker 2: five or ten minutes. The water is generally extremely cold,
13:24
Speaker 2: typically ice icy. Often people will do this and the
13:28
Speaker 2: like low budget version of this. This guy, I've got
13:30
Speaker 2: like a giant backyard like metal tank, and then my
13:34
Speaker 2: Instagram video will have me walking out and like cutting
13:37
Speaker 2: a hole in the ice on the top of my
13:39
Speaker 2: tank and then getting into it, often with my husband
13:43
Speaker 2: or wife, so we can have a romantic popsicle.
13:47
Speaker 1: Worst date night ever, worst date ever.
13:50
Speaker 3: But anyway, so that's so it's very very cold. Of
13:52
Speaker 3: course they also make like.
13:54
Speaker 2: More expensive tubs that will regulate this temperature for you.
13:56
Speaker 2: But it's very cold relatively short period of time. Then
14:00
Speaker 2: there's a sort of hot side of this, which actually
14:03
Speaker 2: is quite a bit more varied. So you can be
14:06
Speaker 2: hot in a sauna, or you can be hot in
14:08
Speaker 2: a hot tub, or actually in sports, you can be
14:11
Speaker 2: hot in like exercising in like a winter coat.
14:16
Speaker 1: Oh yeah, and like hot yoga. Right, I mean, I
14:18
Speaker 1: guess that's a sauna, right.
14:21
Speaker 2: Sua, although it's not like a dry son it and
14:24
Speaker 2: in fact, if you get.
14:25
Speaker 3: Into like the Fins.
14:26
Speaker 2: A lot of the data on saunas from people in Finland,
14:29
Speaker 2: and the Fins have like a lot of really specific
14:31
Speaker 2: things about their saunas, like different kinds of saunas.
14:34
Speaker 3: The saunas are the rocks, the saunas without the rocks,
14:36
Speaker 3: I don't know.
14:37
Speaker 2: At any rate, you are quite hot for a period
14:41
Speaker 2: of time, and typically a bit longer. So sauna or
14:44
Speaker 2: hot tub exposure is often something like a half an hour,
14:48
Speaker 2: you know, longer in the hot tub than than in
14:50
Speaker 2: the sauna, And the idea is just to raise your
14:52
Speaker 2: to raise your body temperature for.
14:53
Speaker 3: Some extended period of time.
14:55
Speaker 2: So basically we're talking about being either very cold or
14:57
Speaker 2: very hot. I think it's just worth saying both of
15:00
Speaker 2: these are uncomfortable. So we're talking about not like a
15:03
Speaker 2: relaxing bath with candles. We're talking about like most people
15:08
Speaker 2: do not enjoy being in a hot tub for thirty minutes,
15:13
Speaker 2: especially since in the heat treatments usually you have to
15:16
Speaker 2: have your arms in, so you're just really hot.
15:19
Speaker 3: Like it's just like really hot and uncomfortable, or really
15:22
Speaker 3: cold and uncomfortable.
15:24
Speaker 1: But but if I had a nice finished sauna in
15:29
Speaker 1: my office right here, and a giant bathtub full of ice.
15:33
Speaker 1: You ask me which one I'd rather spend fifteen minutes,
15:35
Speaker 1: and I'm taking the sauna every day of the week.
15:37
Speaker 2: Just going to say it, I think that's right. I
15:39
Speaker 2: hate being both hot and cold. I just I like
15:42
Speaker 2: to be one intermediate temperature that's perfect. I find both
15:46
Speaker 2: of these ideas like almost unbearable.
15:49
Speaker 3: But I do think I would also.
15:50
Speaker 2: Choose hot, although last time I was in a sauna,
15:53
Speaker 2: I literally made it forty five seconds before I was like,
15:56
Speaker 2: oh my god, I have to leave.
15:57
Speaker 3: I'm going to die.
15:58
Speaker 1: Okay, Oh you're okay. So you're really like your your
16:02
Speaker 1: homeothermia or whatever, meaning yeah, sure, regular persones somewhere somewhere
16:06
Speaker 1: in the middle. But if there are real health benefits, right, like,
16:09
Speaker 1: maybe it's worth it. Maybe what I think we need
16:11
Speaker 1: to figure out.
16:12
Speaker 2: All right, let's before we figure out the health benefits, though,
16:15
Speaker 2: let's talk a little bit about like why these might matter.
16:19
Speaker 2: Like what's the physiology, So you're the doctor, what is
16:22
Speaker 2: the physiology of these kinds of exposures to extreme temperatures?
16:26
Speaker 1: Sure, and let me say like a little bit of
16:28
Speaker 1: philosophy of wellness here where I think this might be
16:33
Speaker 1: a recurring theme in our podcast, which is that in
16:37
Speaker 1: medical science we start with this concept called biologic plausibility,
16:41
Speaker 1: which is is it possible that this thing works? Not
16:44
Speaker 1: does it work? Just like does it make sense? You know,
16:47
Speaker 1: if someone came and said eating red jelly beans cures cancer,
16:50
Speaker 1: I would say there's no biologically plausible way that that
16:53
Speaker 1: is true. It's not really worth your time. Where I
16:56
Speaker 1: think wellness gets it wrong is that they stop there
17:00
Speaker 1: say like, oh, it's plausible and therefore it does. And
17:03
Speaker 1: where we need to go is like, Okay, maybe it's plausible,
17:06
Speaker 1: but like does it actually And there's there's a wider
17:09
Speaker 1: gap between plausible and reality than people often think. So
17:13
Speaker 1: let's first of all, just talk about biologic plausibility. The
17:16
Speaker 1: physiology of cold water plunges is pretty interesting and we
17:20
Speaker 1: have a good amount of data on this, believe it
17:22
Speaker 1: or not, because the military is really interested in what
17:27
Speaker 1: happens to people when they drop into cold water. This
17:30
Speaker 1: is something I guess that we do. We probably do
17:33
Speaker 1: it more often than we know that we do. And
17:36
Speaker 1: so the Department of Defense has funded quite a few
17:39
Speaker 1: studies exploring like the short term and medium terms effects
17:42
Speaker 1: of these cold water plunges. It's not exactly the same
17:44
Speaker 1: as you know, calmly getting into ice water in your backyard.
17:48
Speaker 1: But there's a very standard physiologic response called the cold
17:52
Speaker 1: shock response, which is well described, which happens in the
17:55
Speaker 1: first thirty to ninety seconds of getting submerged in cold
17:58
Speaker 1: water at about forty degrees already five degrees or less,
18:01
Speaker 1: and it is essentially involuntary. It is characterized by a
18:07
Speaker 1: deep and rapid intake of breath, like a feeling yeah,
18:12
Speaker 1: and that's about three liters of air intake. And just
18:16
Speaker 1: to put it in context, breathing kind of normal like
18:19
Speaker 1: in and out is you know, maybe a leader in
18:21
Speaker 1: and out of air intakes, so you're really this very
18:23
Speaker 1: deep breath and this is actually when people fall through
18:26
Speaker 1: the ice or something. This response is what results in
18:29
Speaker 1: a lot of drowning because if your head's underwater and
18:31
Speaker 1: you do that, you just suck in a ton of water,
18:34
Speaker 1: it can be very dangerous. You get this dramatic again
18:37
Speaker 1: first thirty ninety seconds, a dramatic increase in the sympathetic
18:41
Speaker 1: nervous system. This is that fight or flight response, which
18:43
Speaker 1: is going to increase your heart rate, your blood pressure spike,
18:47
Speaker 1: your cortisol levels. It increases adrenaline levels by a factor
18:52
Speaker 1: of about five. In these studies, your adrenaline just goes
18:55
Speaker 1: through the roof in those sixty minutes. Interestingly, dopamine level
19:00
Speaker 1: increase bye two and a half fold. So we often
19:02
Speaker 1: think of dopamine as sort of like a feel good chemical.
19:05
Speaker 1: But you've got a lot of a lot of chemistry
19:08
Speaker 1: going on in that first minute in the ice, and
19:11
Speaker 1: it's obviously not entirely pleasant.
19:14
Speaker 3: What was the pleasant part the dopamine? Oh, the dope
19:17
Speaker 3: mean the don't mean that's going up? But is the
19:19
Speaker 3: dopaine going up? So your body is convinced, like, don't
19:23
Speaker 3: just die right now? Things could improve the next ninety six.
19:27
Speaker 1: Yes, we call it hopamine. It's like, uh, I'll give
19:30
Speaker 1: you a hug and then slap you in the face
19:32
Speaker 1: as hard as I can. I don't know, it's not great.
19:34
Speaker 1: I just want to give the good in the bad. Okay.
19:36
Speaker 1: Vaso constriction So when you get cold, your superficial blood
19:40
Speaker 1: vessels constrict to reduce heat loss to the environment, so
19:44
Speaker 1: blood gets shunted away from your skin and potentially your muscles.
19:48
Speaker 1: I think we need to get into this a little
19:49
Speaker 1: bit to your central organs, which are the things that
19:52
Speaker 1: really need to keep you alive, so like your heart
19:54
Speaker 1: and your brain and your kidneys. To some extent, it
19:58
Speaker 1: also makes you have to pee, and as a kidney doctor,
20:01
Speaker 1: we see this non frequently in the hospital. So after
20:04
Speaker 1: someone has a traumatic brain injury or a stroke, if
20:07
Speaker 1: we catch them in time and they're in very severe cases,
20:09
Speaker 1: we will induce hypothermia. There is some data there for
20:13
Speaker 1: brain injuries that recovery is better with hypothermia, and we
20:16
Speaker 1: do see that as you reduce their body temperature of
20:19
Speaker 1: the year, an output goes up because blood is getting
20:21
Speaker 1: shunted away from the periphery and into the kidneys. So
20:24
Speaker 1: if you jump in that cold plunge pool and then
20:26
Speaker 1: you have to get right out to pee, that's a
20:27
Speaker 1: great excuse. One last thing on physiology, because this is
20:33
Speaker 1: something that's actually potentially dangerous with cold plunges, and that
20:37
Speaker 1: is the mammalian diving reflex. This is a thing that
20:41
Speaker 1: happens when you submerge your face in cold water. It
20:45
Speaker 1: basically is an evolutionary artifact of our instinct to change
20:52
Speaker 1: our physiology when we're swimming, or especially when we're going
20:54
Speaker 1: deep underwater. What happens in the mammalian diving reflex again
20:58
Speaker 1: only if you put your face in the water, is
21:00
Speaker 1: your heart rate goes down. It sort of slows your metabolism.
21:05
Speaker 1: And this is potentially a problem because the cold shock
21:08
Speaker 1: response makes your heart rate go up, the mammalian diving
21:11
Speaker 1: reflex makes your heart rate go down, and there is
21:14
Speaker 1: some evidence that those conflicting signals can precipitate a cardiac arrhythmia,
21:20
Speaker 1: and people have died within the first couple of minutes
21:23
Speaker 1: of a cold plunge potentially through this mechanism.
21:26
Speaker 3: So don't put your face in the water.
21:27
Speaker 1: Don't put your face in the water. Like I saw
21:30
Speaker 1: on a lot of the tiktoks, is like okay, you're in,
21:32
Speaker 1: like now, go all the way and like probably not
21:34
Speaker 1: actually certainly not in the first couple of minutes while
21:37
Speaker 1: you still have the cold shock response going on. So
21:41
Speaker 1: that is the cold side of things.
21:43
Speaker 3: Okay, it sounds terrible. Tell me about being hot.
21:47
Speaker 1: Okay, the warm side I think is a little bit better.
21:51
Speaker 1: So what happens when you're exposed to heat is that
21:54
Speaker 1: your body does stuff to reduce your body temperature. And
21:58
Speaker 1: the thing it does is it dilates blad vessels in
22:00
Speaker 1: your skin so that more blood gets to the skin
22:03
Speaker 1: the surface areas, you can exchange heat better with your environment,
22:06
Speaker 1: and then you do this amazing thing that humans are
22:08
Speaker 1: very proficient at, which is that you sweat. And so
22:12
Speaker 1: one of the reasons those finish saunas can get to
22:15
Speaker 1: such a higher temperature than the steamy saunas is because
22:19
Speaker 1: you have evaporation of sweat, which is cooling you off,
22:22
Speaker 1: whereas if you're in steam, your sweat won't evaporate, So
22:26
Speaker 1: people can tolerate the finish saunas quite a bit better.
22:30
Speaker 1: Because of sweating, you can lose a lot of water
22:33
Speaker 1: through sweat, though you can put out leaders of water
22:37
Speaker 1: in a hot enough sauna you spend enough time there,
22:40
Speaker 1: so dehydration is certainly something to think about. There have
22:43
Speaker 1: been some studies that show that that warmth does release
22:46
Speaker 1: some endorphins, which are sort of you know, endogenous feel
22:49
Speaker 1: good chemicals. So taken all together, it's not as like,
22:54
Speaker 1: oh my god, I'm about to die as a cold plunge,
22:57
Speaker 1: but still might not be pleasant for you. Emily. All right, okay,
23:03
Speaker 1: so now we know what happens, right.
23:04
Speaker 3: Question is whether it's important.
23:06
Speaker 1: Whether it's helpful biologic plausibility wise, there's something here. It
23:11
Speaker 1: does something right. Maybe increasing your part rate is good.
23:14
Speaker 1: It's like a little exercise, you know, vasodilation, phasoconstriction. You
23:19
Speaker 1: could make arguments that these are good things, but we
23:21
Speaker 1: really need to figure out like, okay, are they good things?
23:23
Speaker 1: And I think where ice has got its most data
23:28
Speaker 1: emily is for athletes, right, like particularly like athletes who
23:32
Speaker 1: are really doing endurance stuff. Can you tell me about that?
23:36
Speaker 3: Yeah?
23:37
Speaker 2: So I think both ice and heat are things that
23:39
Speaker 2: people who are doing like serious sports try to experiment with.
23:43
Speaker 3: And I think we sort of start with ice.
23:45
Speaker 2: The idea again to get to the biological plausibility issues.
23:49
Speaker 2: The idea behind ice is sort of similar to, like
23:53
Speaker 2: I have an injury I have which partly is inflammation.
23:57
Speaker 2: You ice your injury. That's like a well known approach
23:59
Speaker 2: to prevention. I think there's a kind of extension into
24:02
Speaker 2: the sort of cold plunges in icing, which is like,
24:05
Speaker 2: well maybe if I just iced my whole body, that
24:08
Speaker 2: would like lower my inflammation overall, and it might improve
24:11
Speaker 2: recovery and ideally improved performance. I mean, I think part
24:14
Speaker 2: of what's I guess is we'll talk about this a
24:16
Speaker 2: lot of them podcasts, But there's actually a lot more
24:20
Speaker 2: research on a lot of these topics in athletes than
24:23
Speaker 2: there is in other people, in part because it's a
24:25
Speaker 2: very easy population to study, because you know what you're.
24:27
Speaker 3: Trying to achieve and it's short term.
24:29
Speaker 2: Right, So you can say, Okay, I'm going to put
24:31
Speaker 2: people in this protocol, dump them in the ice after
24:33
Speaker 2: their you know, cycling test, you know, every day for
24:37
Speaker 2: three weeks, and then I'll do it not for three weeks,
24:39
Speaker 2: and I'll measure their VO two max on a special bike.
24:41
Speaker 3: And blah blah blah.
24:42
Speaker 2: And it's like just much easier to think about what
24:44
Speaker 2: you're trying to accomplish and how to measure it.
24:46
Speaker 3: Yeah, and so many of.
24:47
Speaker 2: The problems we have studying regular people is what we're
24:49
Speaker 2: trying to say is like do you live to be
24:50
Speaker 2: one hundred? And like I can't measure that three weeks
24:53
Speaker 2: from now, obviously exactly, So I will say when we
24:56
Speaker 2: look at ice, my sense of the literal sure is
25:00
Speaker 2: that it's really not that great that these cold plunges.
25:04
Speaker 2: Maybe they have you know, a little bit of an
25:08
Speaker 2: impact on sort of subjective muscle soreness. But in terms
25:12
Speaker 2: of recovery and performance and so on, there just isn't
25:15
Speaker 2: much consistent evidence that these things matter.
25:19
Speaker 1: A lot of the studies have this.
25:21
Speaker 2: Feature that it's like, well, we did this and we
25:23
Speaker 2: looked at these you know, forty seven different outcomes and
25:27
Speaker 2: you know, three of them it mattered, and it's like, yeah,
25:29
Speaker 2: but that's actually not a very statistically robust result. So
25:34
Speaker 2: I for me, the like ice for athletes is a
25:36
Speaker 2: bit of a dud.
25:38
Speaker 1: Yeah, I you know, as I was looking into this,
25:40
Speaker 1: I sort of assumed that at least for the real
25:43
Speaker 1: you know, real athletes, right, like the professional athletes, because
25:46
Speaker 1: you see these like the football players and the baseball
25:49
Speaker 1: players with the professional trainers and everything like, and they
25:52
Speaker 1: have these ice bats in the training house. And I
25:55
Speaker 1: saw enough videos of professional athletes like talking about the
26:00
Speaker 1: process before they get into the ice bath, like what
26:03
Speaker 1: they have to go through mentally and physically. You know,
26:06
Speaker 1: they're like, okay, I've got it because they hate it, right,
26:09
Speaker 1: Like they've got a mentally prepare Like some of them
26:12
Speaker 1: are drinking really hot tea. They're putting on like rubber
26:15
Speaker 1: gloves and boots and things like that. So that they
26:17
Speaker 1: don't get like a schemia of their digits and things.
26:20
Speaker 1: And then they you know, they get in and it
26:22
Speaker 1: has this feeling like, well, it must be really beneficial
26:26
Speaker 1: because they're they're putting themselves into this and and you're right,
26:30
Speaker 1: you know. Looking at the data, I couldn't find much.
26:33
Speaker 1: I found one study that looked at the level of
26:36
Speaker 1: a substance called creatine kinase, which is a muscle enzyme.
26:41
Speaker 1: It goes up when you work out really vigorously because
26:43
Speaker 1: you do damage muscles when you work out hard. In fact,
26:47
Speaker 1: that's the way your muscles get bigger, is that you
26:50
Speaker 1: sort of damage them and then they get they come
26:51
Speaker 1: back stronger, and so CK levels go up after exercise,
26:55
Speaker 1: and the people that they randomize to do the ice
26:58
Speaker 1: bath it didn't peak quite as much. But I'm not
27:01
Speaker 1: sure that means that, like that's even better for you, right, Like, yeah,
27:05
Speaker 1: don't you kind of want some muscle damage? I mean
27:07
Speaker 1: that's right, Like if you're trying to build muscle, I.
27:09
Speaker 2: Mean, yes, you do need to damage your muscles to
27:11
Speaker 2: try to build them. But I think the more generally,
27:13
Speaker 2: like where's the where's the performance out come?
27:15
Speaker 1: There?
27:15
Speaker 2: You know, this is like we're measuring all of these
27:17
Speaker 2: things and like we don't really we don't have a
27:20
Speaker 2: great sense of that that translates into performance. And I
27:22
Speaker 2: think if you look at this sort of true performance stuff,
27:25
Speaker 2: being cold is just we just don't have like a
27:27
Speaker 2: lot of good evidence.
27:29
Speaker 1: All right, professional athletes take notes.
27:31
Speaker 2: On the other hand, I will say I think the
27:33
Speaker 2: evidence on heat in sports is somewhat more compelling.
27:38
Speaker 3: The typical protocol.
27:40
Speaker 2: Here is hot tub, so basically taking people in after
27:43
Speaker 2: their workout, putting them in a hot tub for thirty minutes.
27:46
Speaker 1: This is literally the opposite of what we just talked about.
27:48
Speaker 1: So I feel like both of these can't work.
27:51
Speaker 3: People don't like this either.
27:52
Speaker 2: And actually in some of these protocols, they make the
27:54
Speaker 2: hot tubs really hot, like instead of your your hot
27:58
Speaker 2: tubs supposed top out like hundred four degrees, but they
28:01
Speaker 2: like juke the hot tubs up, so they go up
28:02
Speaker 2: to one hundred and.
28:03
Speaker 3: Seven and then they're like leaving these people.
28:05
Speaker 2: It was like, it sounds horrible, but you do see
28:08
Speaker 2: some performance impacts there, and in particular for people who
28:12
Speaker 2: are going to like race in a hot environment and
28:16
Speaker 2: now we're in like a really really niche area. But
28:18
Speaker 2: if you're like training in someplace cold, but you're going
28:20
Speaker 2: to race someplace hot, there's a lot of benefits to
28:23
Speaker 2: heat acclamation, which you can do in a bunch of ways,
28:25
Speaker 2: one of which is the hot tub. So you know,
28:28
Speaker 2: this is like an I would say there's more evidence
28:31
Speaker 2: for being hot than there is for being cold. But
28:35
Speaker 2: we are still talking about very small Like if people
28:39
Speaker 2: are listening to this and they're like, I'm a recreational
28:41
Speaker 2: runner and I have like I'm you know, I'm trying
28:44
Speaker 2: to like run a five k, Like, you don't need to,
28:48
Speaker 2: the best use of your time is just to exercise
28:51
Speaker 2: and have your regular life, not to get in the
28:53
Speaker 2: hot tub. We're talking about, Like, if you are, you know,
28:57
Speaker 2: a sub elite athlete and you're interested in adding something,
29:00
Speaker 2: I'd add sauna instead of adding cold.
29:03
Speaker 1: Let's talk a bit about for us non athletes. I
29:07
Speaker 1: have to represent my people. You mentioned that the FINS
29:11
Speaker 1: put out a lot of sauna data, some of which
29:15
Speaker 1: is fairly positive when it comes to things like mental
29:17
Speaker 1: health and whatnot, which I always always get a little
29:19
Speaker 1: suspicious when like all the data on something comes from
29:21
Speaker 1: the country that's really invested in it. It's like if
29:24
Speaker 1: the you know, if the Dutch put out like a
29:26
Speaker 1: lot of positive clog studies or something, right, So we'll
29:31
Speaker 1: take it with a grain of salt. Finland, But in
29:34
Speaker 1: terms of subjective well being, it seems like these saunas
29:38
Speaker 1: are good, right, I mean, it's a relaxing thing maybe
29:41
Speaker 1: for some people.
29:42
Speaker 2: Yeah, I mean so, I think the most famous paper
29:45
Speaker 2: on this is a paper about Finland which they looked
29:48
Speaker 2: at long term mortality follow up for men in Finland
29:52
Speaker 2: who spent different amounts of time in the sauna. And
29:56
Speaker 2: you know, we'll talk a lot about studies like this,
29:59
Speaker 2: but there are limitations to a study where you are
30:02
Speaker 2: using what's called observational data, so people weren't randomized. There
30:06
Speaker 2: may be different features between the people who spend seven
30:09
Speaker 2: days a week in the sauna versus two days a
30:11
Speaker 2: week in the sauna. But they find, you know, pretty
30:13
Speaker 2: in that observational data there are quite large impacts on
30:17
Speaker 2: cardiovascular mortality. And it's not inconsistent with some randomized data
30:23
Speaker 2: about sort of cardiovascular improvements and other things like in
30:28
Speaker 2: the heart space as a result of exposure to some
30:31
Speaker 2: of these temperatures. So I think there's like there's sort
30:33
Speaker 2: of a cardiovascular plausibility there. I mean, I'm curious if
30:36
Speaker 2: that lines like. Another way to think about quality of
30:40
Speaker 2: evidence here is to ask whether that effect which sort
30:43
Speaker 2: of seems to be really a kind of cardiovascular effect
30:46
Speaker 2: as opposed to something else, Like it really seems like
30:49
Speaker 2: it's something about the cardiovascular system. Does that line up
30:52
Speaker 2: with what you'd expect based on the physiology of this
30:56
Speaker 2: of the heat.
30:57
Speaker 1: Yeah, yeah, I mean it seem like sauna in is
31:02
Speaker 1: sort of a mild cardiovascular stressor it kicks your heart
31:06
Speaker 1: rate up. It's almost like light exercise in terms of
31:10
Speaker 1: blood pressure changes and heart rate changes. Emily, I see
31:13
Speaker 1: you smiling because and you're right, it's not as good
31:15
Speaker 1: as actually getting exercise, yes, but cardiovascularly there is some
31:20
Speaker 1: of that. This introduces both an opportunity and a problem.
31:23
Speaker 1: The opportunities. Yeah, okay, maybe it is good to get
31:25
Speaker 1: your heart rate up a little bit. However you can
31:28
Speaker 1: I suspect it's better to get it up by walking
31:30
Speaker 1: around the block a few times than by sitting in
31:32
Speaker 1: a sauna. But it's not nothing there. The other thing
31:37
Speaker 1: is something we always worry about in epidemiological studies, which
31:40
Speaker 1: is reverse causation where people who have some cardiovascular problems
31:44
Speaker 1: might not be able to tolerate the sauna as much. And
31:47
Speaker 1: so then when you kind of follow people over time,
31:49
Speaker 1: you're like, oh, people who do more sauna live longer,
31:51
Speaker 1: when in fact it's people who are less healthy do
31:54
Speaker 1: less sauna to begin with, which sort of complicates the issue.
31:57
Speaker 1: But I don't think it's inconceivable that either the cardiovascular
32:00
Speaker 1: benefits or I'm a big believer in the power of
32:04
Speaker 1: like doing something intentionally for yourself, And there's a lot
32:09
Speaker 1: of stuff in this space where I think it's that
32:12
Speaker 1: it's like, Okay, this is me time, right, Like I'm
32:15
Speaker 1: getting in the sauna, I'm not bringing my phone. I'm
32:18
Speaker 1: just sitting and with alone with my thoughts. And maybe
32:21
Speaker 1: you don't even need the heat. Maybe it's just a
32:23
Speaker 1: quasi meditative state that I think actually might be beneficial
32:26
Speaker 1: for mental health.
32:27
Speaker 3: Do you think the same about the cold plunges or
32:29
Speaker 3: is it?
32:30
Speaker 1: No? Not at all, No, because I think in the
32:32
Speaker 1: cold plunge, I think instead of like quietly being with
32:35
Speaker 1: your thoughts, your brain is like, what are you doing?
32:37
Speaker 1: Please leave this horrible place. You're about to die. I'm
32:40
Speaker 1: shutting down your body systems as we speak.
32:43
Speaker 3: Yeah, that's what I think.
32:45
Speaker 2: So one of the things people will sometimes talk about
32:48
Speaker 2: is the idea that saunas are are a detox that
32:52
Speaker 2: you're sweating out the toxins a lot of efforts to
32:55
Speaker 2: get rid of toxin. So do you think that if
32:57
Speaker 2: you sweat more you get more of.
32:58
Speaker 3: Your toxins out? And what are the toxins specifically?
33:01
Speaker 1: No, no, no, no, not a chance at all. You
33:05
Speaker 1: have two organ systems that are designed to detoxify you,
33:10
Speaker 1: the liver and the kidneys. That is their entire revolutionary purpose.
33:13
Speaker 1: They do an amazing job. Sweat is ninety nine percent water.
33:17
Speaker 1: The other one percent is salt sodium chloride. That's what
33:21
Speaker 1: sweat is. So you will lose water, you will lose salt.
33:24
Speaker 1: Both of these are things that nominally you need to survive,
33:28
Speaker 1: and so we would want to replenish those after a sauna.
33:32
Speaker 1: Just to put some numbers in it, there was a
33:34
Speaker 1: study that looked at the excretion of organic pollutants in sweat.
33:40
Speaker 1: So if we're worried about toxins, here's a good one
33:42
Speaker 1: for you. Right. It's the stuff that like we spray
33:44
Speaker 1: on crops and things like that. It's in our system,
33:46
Speaker 1: it gets in our blood. You can measure these things.
33:49
Speaker 1: And so took some people, put them in the sauna,
33:52
Speaker 1: tested their sweat, and they determined that if you were
33:55
Speaker 1: to leave people in the sauna for an entire day
33:58
Speaker 1: and somehow they survey, so you know, getting a ton
34:01
Speaker 1: of sweat out of these people, you would excrete through
34:05
Speaker 1: the sweat zero point zero one percent of the daily
34:08
Speaker 1: accumulation of organic toxins. So there is a measurable and
34:14
Speaker 1: tiny amount, but it is spitting in the hurricane of
34:18
Speaker 1: potential toxins that are out there to try to excretify
34:22
Speaker 1: a sweat. That's not what sweat is designed for. That's
34:24
Speaker 1: what urine is designed for. That's what bile is designed for.
34:26
Speaker 1: You have organs that do this. Sweat is designed to
34:29
Speaker 1: cool you off. It is extraordinarily good at this. If
34:33
Speaker 1: humans are these amazing animals that evolved on the African
34:38
Speaker 1: planes to do persistence hunts against animals that can't sweat
34:43
Speaker 1: as efficiently as we can, and we maintain our cool
34:47
Speaker 1: under the African sun and they collapse of heat stroke
34:49
Speaker 1: and then we kill them like that is where we
34:51
Speaker 1: come from. That is what sweats for not to get
34:54
Speaker 1: your toxins out.
34:55
Speaker 2: Sorry, okay, but I think what people have noticed is
34:58
Speaker 2: good story about the gazelles. But I think what people
35:01
Speaker 2: have noticed is like, if you drink a lot at
35:04
Speaker 2: night and then you go into a sna the next day,
35:07
Speaker 2: you smell like a vodka and that I think people
35:11
Speaker 2: perceive that.
35:12
Speaker 3: To be like, you know, cleansing them from toxins. So
35:16
Speaker 3: is that why is that.
35:17
Speaker 1: Alcohol is special?
35:19
Speaker 3: Alcohol is special? I totally agree.
35:21
Speaker 1: Say more, alcohol and water do not know that they
35:25
Speaker 1: are different chemicals from one another. So virtually throughout the body,
35:31
Speaker 1: alcohol and water are freely exchanged in the solution of
35:37
Speaker 1: your body. So whatever your blood alcohol content is is
35:40
Speaker 1: your sweat alcohol content. It just they go together like that.
35:44
Speaker 1: Now it's not much, but it is enough to potentially
35:48
Speaker 1: be detectable. Again, it is not enough to clear alcohol
35:53
Speaker 1: from your system by any stretch. You have an organ
35:56
Speaker 1: that is designed to do this. It's called your liver.
35:59
Speaker 1: Your liver can clear for an average man, and it varies,
36:03
Speaker 1: but about a drink's worth of alcohol per hour from
36:06
Speaker 1: your bloodstream. Don't try. This gets worse the more takes
36:10
Speaker 1: you have sweating in a sauna, you know, we're talking
36:15
Speaker 1: less than a hundredth of that amount. It's just not
36:18
Speaker 1: the way to get alcoholic.
36:20
Speaker 3: It's not the hangover here that one hope for.
36:22
Speaker 1: No, it's definitely not, in fact, the dehydration that comes
36:26
Speaker 1: from a sauna. It's probably gonna make things worse alsome thanks.
36:29
Speaker 2: Of course, the last thing I wanted to say on
36:31
Speaker 2: the benefits is I came across what I think was
36:35
Speaker 2: an extremely interesting study about women with obesity and PCOS
36:41
Speaker 2: where they did it's a it's a relatively small set.
36:44
Speaker 2: They did actually a pretty short intervention where they sort
36:48
Speaker 2: of put them in the hot tub for an hour
36:51
Speaker 2: a week for eight to ten weeks, and there actually
36:54
Speaker 2: were a bunch of improvements in blood pressure and other
36:59
Speaker 2: cholester all metrics, so no improvements in weight, but just
37:03
Speaker 2: things that looked like, as you said at the beginning,
37:06
Speaker 2: like a little bit like they had exercised, like similar
37:09
Speaker 2: to if you had put people in exercise. So, you know,
37:12
Speaker 2: I think part of what was interesting about that for
37:15
Speaker 2: me was, you know, I think exercise is great, but
37:18
Speaker 2: exercise is not always feasible for everybody and is not
37:21
Speaker 2: something everybody wants to do. And so to the extent
37:23
Speaker 2: that there's a this is sort of something that could
37:26
Speaker 2: be helpful in some cases, maybe on the way to.
37:29
Speaker 3: Exercise, or maybe in addition to it.
37:32
Speaker 2: It feels like there's there's sort of something there that
37:35
Speaker 2: might be meaningful enough that it's.
37:37
Speaker 3: Worth considering for some people. I buy it, okay, but
37:40
Speaker 3: not all people.
37:41
Speaker 2: So what when we sort of talk about are there
37:44
Speaker 2: people who should not do this pregnant?
37:48
Speaker 1: Yeah, yeah, there's always people who should not do everything.
37:51
Speaker 1: You know. Again, if you're curious, if you're one of
37:53
Speaker 1: these people, of course, talk to your doctor. But broadly speaking,
37:57
Speaker 1: both of these hot and cold are mild cardiovass stressors.
38:01
Speaker 1: So people with pre existing heart disease who are at
38:04
Speaker 1: risk of heart disease, you know, certainly can be put
38:06
Speaker 1: at mild risk by going into either of these situations.
38:11
Speaker 1: People at risk of arrhythmias, particularly with the cold plunge,
38:14
Speaker 1: and I'll just say it again, I would not put
38:16
Speaker 1: your face in the water when you're in the cold plunge.
38:18
Speaker 1: The problem with a rhythmias is that a lot of
38:20
Speaker 1: people who at risk of them don't know that they're
38:22
Speaker 1: at risk of them, at least the first time that happens.
38:25
Speaker 1: And so does make me a little bit nervous. Obviously,
38:28
Speaker 1: jumping into a cold body of water, as opposed to
38:31
Speaker 1: like a tub in your backyard has extra dangers because
38:34
Speaker 1: of that cold shock response. You know, people jumping into
38:37
Speaker 1: cold lakes can just like go under and not come up,
38:41
Speaker 1: and it's very hard to find them. Deaths have been described,
38:44
Speaker 1: so you know this is something to take seriously and carefully.
38:49
Speaker 1: I will also mention that there have been some studies
38:52
Speaker 1: if you're a man that is interested in fertility, at
38:57
Speaker 1: least in the short term, that prolonged exposure to heat
39:02
Speaker 1: does kill sperm. And so if you know, if you're
39:06
Speaker 1: you and your partner are trying to get pregnant, it's
39:08
Speaker 1: probably not the best time to do significant sauna or
39:12
Speaker 1: hot tubbing. And women who are pregnant that elevated body
39:16
Speaker 1: temperature can certainly be damaging to the fetus, and so
39:20
Speaker 1: we don't recommend hot, certainly for pregnant women, and I
39:24
Speaker 1: probably wouldn't recommend cold in that case either.
39:27
Speaker 3: Just disagree.
39:29
Speaker 2: Actually, I spend a bunch of time at some point
39:31
Speaker 2: looking at the cold plunge data in pregnancy, and I
39:36
Speaker 2: would say, although you know, of course the data is
39:39
Speaker 2: limited because cold plunging seems terrible and why would you
39:41
Speaker 2: do it?
39:41
Speaker 3: Ever, there actually are.
39:44
Speaker 2: There is some evidence on this is actually no real
39:47
Speaker 2: reason to think that, you know, particularly if you are
39:49
Speaker 2: a person who generally does this, that you would need
39:51
Speaker 2: to stop doing it when you were pregnant, which is
39:55
Speaker 2: not the case of hot dubs and saunas, where the
39:58
Speaker 2: risk for neeral tube defects, particularly for exposure in the
40:00
Speaker 2: first trimester, means that that's a no, no.
40:03
Speaker 1: Fair enough, fair enough, all right, No, saunas may be
40:05
Speaker 1: cold plunges, but be careful.
40:07
Speaker 2: So my last like risk question that I have always
40:11
Speaker 2: wondered about is like, can you get frostbite from being
40:15
Speaker 2: in the like if I get in and I have
40:18
Speaker 2: some exposed parts fingers, toes for men.
40:22
Speaker 3: I mean, aren't you worried your penis is gonna get
40:24
Speaker 3: frozen off? Honestly? Isn't that a thing I would be worried?
40:28
Speaker 1: Well, I hadn't thought about it until just now. Now
40:32
Speaker 1: I'm worried. It's not my go to every time cheese.
40:39
Speaker 1: So typically in frostbite, we imagine that it occurs when
40:44
Speaker 1: the external temperature is below freezing because you have ice
40:47
Speaker 1: crystal formation so that being said, you can get schemic digits.
40:55
Speaker 1: So that response to cold is that the blood vessels
40:59
Speaker 1: in your your superficial blood vessels constrict, and it can
41:02
Speaker 1: be quite powerful. Particularly there's a phenomenon called Renod's phenomenon.
41:07
Speaker 1: Many women have experienced this where and I mean men
41:11
Speaker 1: have it too. It's just more common in women where
41:13
Speaker 1: you have such severe vaso constriction in your finger typically fingers,
41:17
Speaker 1: but it can happen in toes two that it's just white.
41:19
Speaker 1: There's just no blood flow there that can be triggered
41:23
Speaker 1: by cold plunges. And so many people who do this
41:28
Speaker 1: routinely actually wear like some rubber gloves and rubber booties
41:31
Speaker 1: and even rubber boxer shorts. To get to the issue
41:34
Speaker 1: that you are referring to, Emily, to try to make
41:38
Speaker 1: sure that those nibbly bits as we call them in
41:41
Speaker 1: the medical profession don't get exposed to too much of
41:45
Speaker 1: that cold. Broadly speaking, I think if you're healthy and
41:49
Speaker 1: you don't have vascular problems to begin with, even some
41:53
Speaker 1: vaso constriction from the cold plunge that is painful and
41:57
Speaker 1: hurts is not going to result in the loss of
41:59
Speaker 1: a digit the way you could if you were, you know,
42:01
Speaker 1: outside in sub zero temperatures, so you.
42:03
Speaker 2: Won't lose your fingers, but your nibblelybits could be uncomfortable.
42:07
Speaker 3: Thank you.
42:08
Speaker 1: Yes, I'm sorry to use medical jargon.
42:11
Speaker 3: Well it's I think we're gonna be using that in
42:14
Speaker 3: the future.
42:16
Speaker 2: Okay, So Perry, what is your one thing takeaway on
42:21
Speaker 2: cold plunges and saunas for the listener.
42:25
Speaker 1: Cold plunges seems like modern day self flagellation. Be kind
42:29
Speaker 1: to yourself. I don't think it's worth it. Saunas, sure,
42:33
Speaker 1: go for it, primarily because it's a nice time to
42:36
Speaker 1: have some time to yourself and relax, which we all
42:38
Speaker 1: need more of.
42:39
Speaker 3: My one thing is similar.
42:41
Speaker 2: What I would say is if hot tub sauna on
42:45
Speaker 2: a regular basis sounds like something that would serve you
42:49
Speaker 2: emotionally or in some other way, then that seems lovely.
42:54
Speaker 2: And in fact, if getting in this ic tub in
42:57
Speaker 2: your backyard would serve the same things and that's a
43:00
Speaker 2: nice date, that also seems fine.
43:02
Speaker 3: Up to the concerns.
43:04
Speaker 2: But for most people, I don't think I would invest
43:08
Speaker 2: in either of these for significant health benefits. There are
43:12
Speaker 2: a lot of other things I would put on the
43:13
Speaker 2: list for people first.
43:15
Speaker 1: Sounds good. We will be back right after this with
43:19
Speaker 1: your questions, and we're back with our listener question of
43:28
Speaker 1: the Week.
43:29
Speaker 4: Hi, Emily and Perry. This is Ellie from Toronto, Ontario.
43:34
Speaker 4: So I'm a parent in my late forties, and I've
43:37
Speaker 4: been running on about five or six hours of sleep
43:41
Speaker 4: at night for well many many years.
43:46
Speaker 3: So my question is I.
43:48
Speaker 4: Function, you know, I mean, I get through my day.
43:51
Speaker 4: I've convinced myself that I've totally adapted to that amount
43:54
Speaker 4: of sleep and it's fine.
43:56
Speaker 3: But I keep.
43:57
Speaker 4: Hearing that chronically not getting enough sleep can kind of
44:02
Speaker 4: damage your health quietly, and so I'm wondering is regularly
44:07
Speaker 4: getting this amount of sleep harmful if you feel fine? Like,
44:12
Speaker 4: what does the research say about long term effects on
44:16
Speaker 4: things like, you know, like my metabolism or my heart
44:20
Speaker 4: or my mood, my weight, et cetera. And then I
44:24
Speaker 4: guess the last pieces. If someone can't realistically get eight hours,
44:29
Speaker 4: what are the most meaningful ways to reduce the damage.
44:33
Speaker 3: Thank you, Emiley.
44:35
Speaker 1: I'm so excited about this question because I get to
44:38
Speaker 1: talk about familial natural short sleep, one of my favorite
44:43
Speaker 1: and most awesome genetic conditions. So there are people out
44:47
Speaker 1: there literally who do not need to sleep as much
44:49
Speaker 1: as other people. Approximately one percent of the population have
44:53
Speaker 1: this genetic condition called familial natural short sleep. I will
44:58
Speaker 1: point out that it's not a syndrome or a disease
45:00
Speaker 1: because it doesn't cause any problems. In fact, it seems
45:03
Speaker 1: to be quite beneficial. These people need to sleep about
45:06
Speaker 1: four to six hours a night, they suffer no ill effects.
45:10
Speaker 1: They might even be protected against Alzheimer's disease. There's some
45:14
Speaker 1: suggestion there it is inherited through families. But the fact is,
45:18
Speaker 1: unfortunately that most of us aren't lucky enough to have
45:22
Speaker 1: the special genetic mutation that prevents demension and makes you
45:25
Speaker 1: not have to sleep at night.
45:26
Speaker 3: How would I know?
45:27
Speaker 2: So like before we get into regular people, how would
45:29
Speaker 2: I know if I had this mutation?
45:31
Speaker 1: You might know because you sleep four to five hours
45:34
Speaker 1: a night and feel completely fine, or at least you
45:36
Speaker 1: might be. You might suspect. And then many of the
45:39
Speaker 1: genes are actually known, so if you know, if you
45:41
Speaker 1: were genotyped, they could detect that you had this variation.
45:44
Speaker 3: That is fascinating.
45:45
Speaker 2: However, most of us do not have this variation, and
45:48
Speaker 2: most of us need more than this amount of sleep.
45:51
Speaker 3: That this person is getting.
45:52
Speaker 2: I mean, I so, first of all, I just think
45:54
Speaker 2: we underestimate how important sleep is. I think most adults,
45:58
Speaker 2: especially adults who have jobs and et cetera, kind of
46:02
Speaker 2: think of sleep like a sort of nice to have,
46:05
Speaker 2: you know, sort of like a pedicure, right, Like you know,
46:08
Speaker 2: it'd be great if I could get one, my feet
46:09
Speaker 2: would look better, but like if I can't get one,
46:11
Speaker 2: it's totally fine. And I sort of think people should
46:14
Speaker 2: think of sleep much more like a biological necessity, like
46:18
Speaker 2: and if you don't get enough sleep, it's like torture.
46:21
Speaker 2: I mean, sleep deprivation is a form of torture.
46:23
Speaker 3: And we know that.
46:25
Speaker 2: People's working memory and executive function is affected by even
46:30
Speaker 2: relatively limited limitations on amount of sleep. So they have
46:33
Speaker 2: these studies where they'll take away, you know, a couple
46:36
Speaker 2: hours a night for some period of time, and over
46:38
Speaker 2: a few days of that, you actually end up with
46:40
Speaker 2: a level of functioning that's not dissimilar to if you
46:42
Speaker 2: literally skip the night of sleep. And it's especially hard
46:45
Speaker 2: on working memory, which is something that when you think
46:50
Speaker 2: I need to do something and then you go into
46:52
Speaker 2: the other room and you've forgotten what it is. That's
46:55
Speaker 2: your working memory, and that's not good if you are
46:57
Speaker 2: not sleeping enough.
46:58
Speaker 3: Yeah.
46:58
Speaker 1: I couldn't agree more. It's super important. Most people need
47:01
Speaker 1: about six and a half to eight and a half
47:03
Speaker 1: hours a night. People do very a little bit around there,
47:05
Speaker 1: but you really got to get it in there. You've
47:07
Speaker 1: got to prioritize it the same as you think about
47:09
Speaker 1: like getting some exercise or eating well or whatever. It
47:11
Speaker 1: is a critical thing to focus on, so do your best.
47:14
Speaker 2: I will also say, you know, I want to recognize
47:17
Speaker 2: that it is really hard to get enough sleep and
47:20
Speaker 2: that for a lot of people listening to this, you
47:21
Speaker 2: probably have multiple jobs and multiple children. And so this
47:26
Speaker 2: is partly you know, giving yourself a break and saying like, hey,
47:29
Speaker 2: if I'm not in bed you know at ten o'clock
47:31
Speaker 2: fully asleep and up at you know six, like Brian Johnson,
47:35
Speaker 2: like it's okay, Like you're not going to immediately die.
47:38
Speaker 2: But it's also saying, you know, this should be something
47:41
Speaker 2: you prioritize, and so thinking about, you know, what is
47:44
Speaker 2: feasible for me to improve my sleep. I think that's
47:47
Speaker 2: something that we should care about. And I think at
47:50
Speaker 2: some point we should do a whole episode on the
47:51
Speaker 2: science of sleep, because I love the science of sleep.
47:54
Speaker 3: Every animal sleeps, It's so interesting.
47:56
Speaker 2: Dolphins sleep, has their brains at a time while they're swimming.
48:00
Speaker 3: I'm going to pull out so many great facts for you.
48:02
Speaker 2: So, Perry, do you have any quick tips for better
48:05
Speaker 2: sleep if someone wants more sleep?
48:07
Speaker 1: The standard sleep hygiene stuff here, which is, you don't
48:09
Speaker 1: want to drink caffeinated beverages typically after like four pm.
48:13
Speaker 1: You might not even want to drink any beverages as
48:15
Speaker 1: you approach eight o'clock nine o'clock at night, just so
48:18
Speaker 1: you don't have to wake up in the middle of
48:20
Speaker 1: the night to pee. We want people sleeping in dark,
48:24
Speaker 1: quiet rooms as much as possible. Those noise machines and
48:26
Speaker 1: stuff can actually disturb sleep a little bit if you
48:28
Speaker 1: are an allowed environment. Ear plugs are awesome if they're
48:31
Speaker 1: comfortable for you, and the bed is a place to
48:35
Speaker 1: sleep and have sex, not to eat and watch TV
48:38
Speaker 1: and be on your phone and whatnot. I'm okay with
48:42
Speaker 1: reading in bed, but I would read an actual book
48:44
Speaker 1: as opposed to a phone, because that blue light that
48:46
Speaker 1: comes from the screen can actually keep you up a
48:48
Speaker 1: little bit.
48:49
Speaker 3: That's it.
48:53
Speaker 1: Join us next week when we ask what's the deal
48:55
Speaker 1: with the blockbuster weight loss drugs GLP ones.
49:00
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49:06
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49:34
Speaker 3: We'll let the influencers have the last word, all.
49:36
Speaker 5: Right, guys. So I am three weeks into cold Plunging,
49:39
Speaker 5: and I'm going to explain to you, guys the differences
49:41
Speaker 5: I'm noticing and whether I think this is worth it
49:44
Speaker 5: or not for you guys to go out and get
49:45
Speaker 5: a cold plunge for yourself.
49:46
Speaker 1: Or build one.
49:47
Speaker 5: But I've been doing it for three weeks now, every
49:49
Speaker 5: single morning, and I will tell you the very first
49:52
Speaker 5: thing is that I highly underestimated how much I was
49:56
Speaker 5: not going to want to get into that cold plunge
49:58
Speaker 5: every day