Sauna effect on heart rate • Hacker News Board

Re: Sauna effect on heart rate

#71

Post by gjulianm » Mon, Apr 20, 2026, 2:43 PM UTC

HelloMcFly wrote: post #25

bluGill wrote: post #6

Earlier quoted context omitted.

The most important thing you didn't measure: does this affect long term health in the same way exercise it known to. That is can I put a TV in my sauna and watch that for an hour every day instead of getting out and exercising - yet get the same better long term health outcomes? My current guess is no. That is this improves a marker for good health without improving health. However this is a guess by someone who isn'…

> That is this improves a marker for good health without improving health There is a substantial body of existing research to peruse about the impact of regular sauna use on health outcomes, much of it from Finland given the prevalence of sauna usage there allowing for larger sample sizes. It's a body of evidence rather than one knock-out experimental design.

Much of that body of evidence relies on self-reported and self-assigned sauna usage rather than actual randomized trials, and also the papers show massive risk reductions that do not really fit with the country-level data (e.g., if saunas are that good for cardiovascular health and finns use them that much, why do they have similar rates of CV disease as neighboring countries that don't use that much sauna?)

Re: Sauna effect on heart rate

#72

Post by renewiltord » Mon, Apr 20, 2026, 2:44 PM UTC

preya2k wrote: post #15

KeplerBoy wrote: post #9

Earlier quoted context omitted.

There are different kinds of saunas. Nobody gets into a 90c humid sauna, that would just kill you.

Oh I can assure you, millions people in the northern europe do exactly this ;) EDIT: I guess it depends on your definition of "humid". But 90C and regular water infusions are pretty common sauna conditions.

I mean yes it depends on your definition of humid but if your definition of humid is under 20% RH then that's not in agreement with any other humans on the planet and if it's over 50% RH then no, millions of people are not doing this because they would die. Our bedroom is at 50% RH because under that our baby's skin dries out. There's no way anyone is sitting in a 90 C 50% RH sauna for any appreciable amount of time. They would die.

Re: Sauna effect on heart rate

#73

Post by GordonS » Mon, Apr 20, 2026, 2:45 PM UTC

shevy-java wrote: post #64

bluGill wrote: post #52

Earlier quoted context omitted.

Problem is sauna use and genetic factors corrolate too strongly to make any conclusion to the broader population. If you live in/near Finland you likely sauna often, as have all your ancestors for thousands of years. If you don't live there both are false. Thus we can't know if Sauna is helpful for the general population who isn't of a Finish background.

Japan has a +4 years lead of life expectancy over Finland; Norway almost +3 years on Finland. I am not saying this is conclusive per se, but to me the sauna-people-live-forever is not backed up by the data. I would instead reason that, e. g. weight correlates a lot more here.

Maybe eating a lot of fish, rather than meat, has an impact too.

Re: Sauna effect on heart rate

#74

Post by trklausss » Mon, Apr 20, 2026, 2:45 PM UTC

nyjah wrote: post #42

bluGill wrote: post #6

Earlier quoted context omitted.

The most important thing you didn't measure: does this affect long term health in the same way exercise it known to. That is can I put a TV in my sauna and watch that for an hour every day instead of getting out and exercising - yet get the same better long term health outcomes? My current guess is no. That is this improves a marker for good health without improving health. However this is a guess by someone who isn'…

Zero shot you'd make it an hour in a proper sauna for an hour. People have this idea that saunas are always enjoyable. I sauna daily, and its nice up to a point. For me thats like 10-12mins in. From then on, its tough.

You are clearly not Finn (/s)

Re: Sauna effect on heart rate

#75

Post by tester756 » Mon, Apr 20, 2026, 2:45 PM UTC

bluGill wrote: post #6

kyriakosel wrote: post #2

Author here. Methodology upfront because I'd ask the same things: Data: daily records from wearable users who logged sauna sessions via connected apps. Within-person design — each user is their own control, comparing their own sauna-day nights against their own non-sauna-day nights. No cross-user comparisons. Stats: paired t-tests, FDR-corrected p 0.2 threshold for "meaningful effect." Anything below d=0.2 we don't r…

The most important thing you didn't measure: does this affect long term health in the same way exercise it known to. That is can I put a TV in my sauna and watch that for an hour every day instead of getting out and exercising - yet get the same better long term health outcomes? My current guess is no. That is this improves a marker for good health without improving health. However this is a guess by someone who isn'…

One hour in sauna? :O

Re: Sauna effect on heart rate

#76

Post by bluGill » Mon, Apr 20, 2026, 2:45 PM UTC

shevy-java wrote: post #64

bluGill wrote: post #52

Earlier quoted context omitted.

Problem is sauna use and genetic factors corrolate too strongly to make any conclusion to the broader population. If you live in/near Finland you likely sauna often, as have all your ancestors for thousands of years. If you don't live there both are false. Thus we can't know if Sauna is helpful for the general population who isn't of a Finish background.

Japan has a +4 years lead of life expectancy over Finland; Norway almost +3 years on Finland. I am not saying this is conclusive per se, but to me the sauna-people-live-forever is not backed up by the data. I would instead reason that, e. g. weight correlates a lot more here.

Nobody is claiming they live forever. The claim is sauna use increases lifespan. There are other factors than just sauna use in lifespan though. The question is would the Japanese live even longer if they were using a sauna?

Re: Sauna effect on heart rate

#77

Post by kazga » Mon, Apr 20, 2026, 2:45 PM UTC

mminer237 wrote: post #40

nsbk wrote: post #21

Earlier quoted context omitted.

I recently listened to a podcast about the benefits of sauna or deliberate heat exposure and the gist is that if you get your core temperature at about 39 degrees celsius your cardiovascular system is working comparably hard to light exercise. My take is that your heart and lungs are working out, even if your body is not. Do you get the same benefits as going for a run or bike ride for a comparable amount of time? no…

Edit: I posted this accidentally when editing without noticing. Hypertrophy isn't necessarily a bad thing. I thought I was discarding the comment cuz I realized I was out of my depth. whoops Please ignore my comment, though I will leave it to make the below comments less confusing. Original: You don't want to "work out" your heart though. Cardiac hypertrophy is a bad thing. The benefit of exercise is that your muscle…

Not true. You can't really train your muscles to use less oxygen for the same energy output (what "oxygen-efficiency" would imply). You rather increase their capacity to take up oxygen from the blood and burn it. They will use more oxygen to output more energy.

That additional oxygen needs to come from somewhere. Endurance training at the same time trains the heart to deliver more oxygen to the periphery; the primary mechanism is increased cardiac stroke volume.

Re: Sauna effect on heart rate

#78

Post by tuukkah » Mon, Apr 20, 2026, 2:46 PM UTC

nyjah wrote: post #42

bluGill wrote: post #6

Earlier quoted context omitted.

The most important thing you didn't measure: does this affect long term health in the same way exercise it known to. That is can I put a TV in my sauna and watch that for an hour every day instead of getting out and exercising - yet get the same better long term health outcomes? My current guess is no. That is this improves a marker for good health without improving health. However this is a guess by someone who isn'…

Zero shot you'd make it an hour in a proper sauna for an hour. People have this idea that saunas are always enjoyable. I sauna daily, and its nice up to a point. For me thats like 10-12mins in. From then on, its tough.

When it doesn't feel enjoyable anymore, you're supposed to get out of the sauna and cool down - preferably in a lake. Then repeat as many times as you like.

Re: Sauna effect on heart rate

#79

Post by ricardobayes » Mon, Apr 20, 2026, 2:47 PM UTC

RankingMember wrote: post #49

ricardobayes wrote: post #34

Earlier quoted context omitted.

My take is probably too nuanced here, but the reality is that we don't know. People living in areas with longevity (blue zones), didn't really excercise (as in sports) or take multivitamins. For all we know, it might even come out that regular, gym-style excercise is even worse for longevity. Nordic people tend to live a long life even though they historically didn't have access to fresh vegetables or fruit and bruta…

> I'm not arguing that excercise is unhealthy, it's just that its contribution to eventual longevity, is currently unknown I see numerous studies indicating that exercise contributes directly to eventual longevity, e.g.: https://www.ama-assn.org/public-health/prevention-wellness/m... https://www.acc.org/latest-in-cardiology/articles/2025/07/02... https://pmc.ncbi.nlm.nih.gov/articles/PMC3395188/

Thank you for the resources.

I do wonder what the correlation is: is it only because of excercise, or at least partially also due to the fact those who can set aside time and effort (and often, money) to exercise, have a "better" life than those who don't?

For example, high life expectancy in Madrid, and Switzerland are often attributed to having broad access to great healthcare and stress-free lifestyle(both), despite living a relatively "unhealthy" lifestyle, at least in Madrid. Eating fried food everyday, little exercize among elderly (at least if you don't count walking to the bar). Those 85 year+ Madrileños probably had their last formal exercise when they had to do their military service back in the day.

As in the case of top athletes, in your second article, is their longevity due to heavy exercise, or kind of, "despite it", and at least partially due to their accumulated wealth, health-conscious mindset plus the ability to afford a stress-free life?

Re: Sauna effect on heart rate

#80

Post by Arch485 » Mon, Apr 20, 2026, 2:48 PM UTC

strangescript wrote: post #51

Anecdotal, of course, but the biggest change I ever made in my life was right before bed: take a screaming hot shower with dim lighting. I'd say 95% of the time, I get in bed and just pass out and have no real memory of time passing before falling asleep.

Increasing skin temperature is known to induce sleep (can't find a source currently, sorry). Something about your skin being warmer allowing your body to cool more effectively, I think.

So a hot shower before bed is actually great for sleep, because you get the increased skin temp, relaxed muscles from the warm water, and general relaxation because showers are (for many people) relaxing.