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Comment by infinite_salt | Hacker News Reader

Humans weren't optimized to endure the unnatural extreme heat of a 175 degree sauna, yet studies point to frequent sauna use being associated with a reduction in all-cause mortality

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> yet studies point to frequent sauna use being associated with a reduction in all-cause mortality

Is this perhaps because frequent sauna access is correlated with higher socioeconomic status/less stress/more free time/etc. What kind of confounding factors did they include in that study?

I don't think so. Saunas are economically available to almost everyone (where there is fuel). I grew up a yooper in Upper Michigan and saunas are a very common part of the culture and even folks without indoor plumbing (much less common now) would have wood-burning saunas in the back yard. Saunas are one of the most relaxing, and invigorating, experiences I know of.

> Saunas are economically available to almost everyone

This can't possibly be true. 65% of Americans are living paycheck to paycheck. They definitely aren't in a position to get a Sauna.

And besides, just because people can afford to do something, doesn't mean that less wealthy people do. Almost anybody could afford to golf, but that doesn't mean golf doesn't skew wealthy if you're looking at the people who actually play. If you looked at how long people who golf live vs people who don't, I'd be willing to bet that golfers live longer. I'm not about to suggest that golf is what is keeping them alive though.

Golf takes gear, course access, and above all large amounts of free time. It's certainly not something almost anybody can afford to do. Access and the time to commit are things those with higher economic status often take for granted when considering whether everyone can afford some activity. These factors likely come into play for saunas too - they're not a staple for any given city gym, for sure, which means you need access to a more well-outfitted gym, or to have a sauna in your own home. And then, again, free time beyond the essentials of fitness and daily life.

Yes, that is exactly my point. Anybody could golf, but it isn't practical for people who don't have a good amount of expendable income, so they don't do it. Same thing with saunas.

What do you think the costs associated with saunas are, beyond a towel and sometimes a swimsuit?

You and I have a different view of what a sauna is. My sauna in the UP is simply wood-sided shack, interior cedar board, and a wood burning sauna stove (basically a plain wood stove with free rocks on top) bought locally for around $600, and all going strong since 1998.

Here at home I belong to a gym for $55/ month and sauna there almost daily, and in prior home in Green Bay, each YMCA had a sauna included with membership. Mostly northern cultures and many southern have had something similar for thousands of years. The Oneida tribe outside Green Bay has regular sweat lodge ceremonies, same basic thing. I won’t enumerate the benefits of a true deep heating sauna but it is deeply meditative for me. This is one of the healthy ways to relax that is often available if sought out. Even during a recent trip to Orlando, I was able to sauna at one of the Y’s. My dad (86 yo) saunas at his health club near his home in SC.

I have never heard saunas described as something outside normal economic lifestyles.

A sauna costs about 1k$usd delivered.

And you're suggesting this isn't cost prohibitive to a huge number of people?

Initial outlay is high, but it has no wear. Mine is 8 years old, easily could go another 10. So 5$/mo over 20 years.

> Saunas are economically available to almost everyone (where there is fuel).

And if there isn't fuel, they can simply relax by the pool.

Let them eat cake.

Interesting saunas being associated with wealth, we come from different places. When I was in college at Michigan Tech in the early 80’s, dorms had saunas, the frat house had a sauna, and if you were lucky, someone was renting a place with a sauna. Of course I understand that this was very much a regional thing, the point is they are simple to construct and simple to maintain.

While there, I became friends with an old Finnish couple about 10 miles east of town near the Lake Superior shores. They explained that until just a few years ago (at that time), people had outhouses, and a sauna for relaxing, bathing and socializing. They did not eat cake. (They ate pasties :-) )

Do you really think that the people who worked on this study didn't consider your knee-jerk level-1 confounding factor? Obviously they look socioeconomic status into account when they were studying all-cause mortality, what study wouldn't?

I'm not making that assumption, I'm asking what factors they included. Lots of studies are poorly run and fail to account for very simple confounding factors.

The big study was a 20+ year observational study in Finland [1] where Sauna's are supposed to be quite accessible, but the world is complicated and there are probably many confounding factors.

The mechanism of action seems very plausible. Sauna's are moderate stress which spikes your heart rate temporarily (they say 100-150bpm in the study). So it's not surprising it could be protective for cardiovascular disease just like many other forms of moderate stress/exercise.

[1] https://jamanetwork.com/journals/jamainternalmedicine/fullar...

I don’t mind people asking obvious questions. Even if the answer is also obvious, it’s still an important base to cover, and we shouldn’t assume it was. The humanities is replete with flawed studies.

There is a reproducibility crisis in many fields where people tacitly assumed everyone else was doing their due diligence. Many basic assumptions about confounding factors, confidence values, etc are still being criticized and revisited. You should not assume that such factors have been accounted for, instead you should join in continually asking if they have been and challenging all assumptions.

The first one I head of was https://academic.oup.com/ageing/article/46/2/245/2654230, which did not consider income but did consider other typical biomarkers of health (HDL/LDL, BP/HR, smoking, etc)

Emerging evidence suggests a plausible mechanism is the "heat-shock response", which upregulates a lot of crap related to cleaning up misfolded (= aggregatey) proteins, like protein degradation and chaperone protein expression. Where most of these neurodegenerative diseases AD, PD, some dementias, CTE, prion diesases etc. involve protein aggregation at some point whether necessary-and-sufficient or just along for the ride. Like at this point if some kind of degenerative disease isn't thought to relate to protein aggregation, it's more likely nobody's bothered to look for it

Anecdotally/personally, it seems like there's kind of a step response going from "not cooked" to "cooked", the good stuff doesn't happen until you get "cooked" (ideally remaining that way for a while), and this seems to happen around a body temperature of 38.5-39C.

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