The Straight Dope - Does a sauna or steam room do you any good?

I love to go to the steam room (or if there isn’t one, the sauna) after a workout. But I’ve always wondered: Do they really help? Or rather: I sweat a lot in the steam room, and it’s obviously doing something to my body, but what exactly are its benefits? Or is it actually damaging my body?
— Ricardo Cámara

You know I like to be emphatic in these columns, Ricardo, so I wish I could tell you that, yes, steam rooms and saunas will cleanse your body of noxious substances and, when combined with regular steak dinners, orgasms, and chocolate cake, will enable you to live to 126. Or, alternatively (really, I’m not fussy, I just want something definite to say), that the sauna is a cabinet of death. Once again, however, I find myself stymied by intransigent reality. The scientific evidence, sorted into piles, breaks down as follows:
1) Steam rooms and saunas are good for you.
2) Steam rooms and saunas are bad for you.
3) We can’t decide about steam rooms and saunas. Give us another hour, and see if you can rustle up some baby oil and a lava lamp.
My drab elaboration on these conclusions is provided below. You’ll notice I treat saunas and steam rooms together, although they’re two separate things. Saunas typically operate at 176 to 212 degrees Fahrenheit and a relative humidity of 10 percent to 20 percent, whereas steam rooms involve lower temperatures and much higher humidity (i.e., steam). Now, nearly all the research out there focuses on saunas, and one ought not to assume that what’s true of saunas will in all cases be true of steam rooms. Nonetheless, the two share a key feature, namely, they both make you sweat — perhaps insufficient commonality for a peer-reviewed journal, but good enough for me. We proceed to the results:

Good. “Very few sudden deaths take place during or after sauna bathing” (American Journal of Medicine, 2001). This may not strike you as a ringing endorsement, but at one time saunas were thought to be associated with sudden death, arrhythmia, and heart attacks. Sudden death and heart attacks are now off the list. I hope this fills you with a golden glow.
Bad. “Almost all (221 of 228) hyperthermia deaths in Finland from 1970 to 1986 took place in saunas” (same source). This may undermine any confidence derived from the previous item, but perhaps it helps to know most of the overheated dead were middle-aged men under the influence of alcohol — admittedly a pretty large group.
Good. One study says sauna therapy helped a woman who had a “chronic, debilitating multisystem disorder of 20 years’ duration” due to toxic chemicals discontinue her medications and return to work. Another says saunas improved the condition of firefighters left with neurological problems after PCB exposure. The assumption appears to be that these people excreted the harmful substances in their sweat, which maybe they did. Then again, you can excrete harmful substances in other perfectly ordinary ways, and if it’s sweat you want, you can get plenty through exercise. But how much fun is that?
Sounds good but isn’t really. You can lose a pound or more of water in the sauna. But once out you gain the weight right back.

Good. Saunas can help people with chronic heart failure, asthma, or chronic bronchitis; reduce pain and increase mobility in the arthritic; and enhance resistance to the common cold. They also decrease lung congestion and seem to lower blood pressure in those with hypertension.

Bad. Saunas are a bad idea during a high-risk pregnancy, and are also contraindicated for various cardiac conditions other than chronic heart failure. Clearly if you’re a heart patient thinking sauna, you’d first better ascertain exactly what you’ve got.
Can’t tell. Numerous websites, among them Wikipedia, claim research by the University of Munich’s Institute of Medical Balneology and Climatology shows that saunas and steam rooms confer benefits ranging from improved sleep to softer skin. But good luck finding a citation to back this up. Despite determined effort, including correspondence with actual Germans, my assistant Una could confirm only that the Institute of MB&C exists but is now called the Institute for Health and Rehabilitation Sciences. Beyond that, zilch.
By now maybe you’re saying: This is all very interesting, but I’m not pregnant and don’t have asthma, PCB poisoning, or any of the other baleful conditions alluded to above. I just like steam baths and saunas. Are they good or bad?
That’s what I’m trying to tell you. If you’re in good health, a sauna (and maybe a steam bath, although in the absence of more data one needs to be cautious on this point) won’t kill you, possibly may help (fewer colds), and in any case will leave you, however briefly, with a sense of radiant well-being, a circumstance to be cherished in this melancholy age. What more do you want?
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