Saunas and steam-rooms

Recently I walked into the "steam-room" in my local rec center, where I am a regular, and sat down. A fellow regular was leaning against the far wall, shrouded in steam; and beside me chatted a young couple. Suddenly, I noticed that the couple was looking at me.

"Uh, excuse me?", said the young woman, her voice echoing off the tiles.

"Yes?", I said, turning toward her. 

"You're bleeding", she said. I looked down and saw a small trickle of blood running down my leg from a small, mysterious cut on my knee. 

"Oh! So I am!", I said, surprised. Then, noting the insignificance of the cut, and not wanting to immediately leave the comfort of the steam-room to address it, I looked at her and asked "do you mind?"
A familiar chuckle came from the back of the room.

"No", said the woman. Then she added, "but it's not going to stop bleeding if you stay in here."

"Really?", I said quickly, and watched her expression for clues that maybe she knew something that I didn't. But the woman looked at me with surprise, as if it was common knowledge that blood won't clot in the steam-room. Then she shrugged and went back to talking with her boyfriend, apparently leaving me to bleed to death, had I so chosen.

I immediately suspected that the young woman was under the impression that blood clots because the air 'dries it out', in much the same way that the toothpaste in the tip of the uncapped tube becomes hard and crusty. This is because I had long assumed the same thing; and only while taking a course in cell biology did I discover that blood-clots actually form in response to blood vessel damage. So a cut should stop bleeding at approximately the same rate regardless of humidity. (Of course, this helps explain how it is that blood-clots can sometimes form internally.)

But the woman didn't seem eager to pursue the subject any further, so I kept my mouth shut. It was easy for me to do this, because as a regular in the steam-room I get lots of practice. For example, it is common steam-room wisdom that exposure to the heat and steam bestows significant health benefits. I certainly find the steam-room relaxing, but am I really relaxing my way to health and longevity?

Heat: The Cure for All Disease?

Allegedly, the ancient Greek philosopher Hippocrates once said " give me the power to create a fever and I shall cure any disease"; people in the steam-room sometimes say that they are there "sweating out a cold"; and those in the steam-room/sauna business will sometimes attempt to convince you that steam-rooms and saunas will help you to "stay free of disease". 

Actually, at first all this made perfect sense to me: after all, fevers are a wonderful defensive mechanism that can at once help to slow the reproduction of invading pathogens (like the flu virus) and enhance your body's capacity to combat infections. So it intuitively follows that if you warm yourself in a sauna, you are effectively making your body temporarily less habitable for any pathogenic viruses or bacteria that may have just begun to colonize you.

But now I wonder if I wasn't too quick to assume that a fever and a sauna both effect my body in the same way. For example, during a fever, your body increases its core temperature by shunting blood away from your skin and toward your internal organs; whereas in a sauna, your body is still actively trying to maintain its normal internal temperature (about 37 degrees C), and one of the ways it does this is to shunt blood in the exact opposite direction: away from your internal organs and toward your skin (this is accomplished by the selective contraction of blood vessels - very cool). Moreover, during an actual fever your body will do more than just cook: for example, it will also produce elevated quantities of "interferon" (proteins that "interfere" with the reproduction of viral DNA). I'm no doctor, but all this makes me very suspicious of claims that a sauna effectively induces an artificial fever.

(Another thing I'd like to get off my chest is that going to a public sauna when you know you are sick is probably not the most responsible move you could make.)

Toxic Sweat?

Repeatedly I hear it asserted that sweating in the sauna helps remove "toxins" from the skin. But there are two small problems with this assertion: the first is that sweating does not actually cleanse your body of toxins; and the second is that the toxins do not really exist.

Interestingly, only mammals sweat; and most mammals don't sweat nearly as much as we humans do. Less sweaty or sweat-less animals (like reptiles, pigs, and whales for examples) seem to get by just fine without being able to "cleanse" their skin by perspiring appreciably. So when you think about it, why should sweat glands do anything more than cool us, when our bodies can rid themselves of waste in the same way that these animals so effectively can?

Considering this, it is unsurprising that sweating doesn't actually cleanse your body of too much more than water and water-soluble substances like electrolytes.

In any case, the term "toxin", although it is a scientific term, is used improperly here, as it all too often is. This is important to realize, because none of the substances that I assume people are referring to when they say "toxin"  (namely "metabolites"; "heavy metals" like mercury and lead; bacteria; viruses; and "free radicals") are eliminated in significant quantities via perspiration. Furthermore, terms like "toxins" or "detoxification" are worth watching out for, as their ambiguity makes them irresistibly attractive to the unwittingly ignorant and the willfully deceptive alike.

Steam-Rumors?

What about the steam? Is it any good for your sinuses or lungs?

Again, my impression is that, although steam inhalation may be a suitable measure in certain medical cases, it's effect on healthy individuals is more or less negligible; and, again, there appears to be little evidence that it will be of much use to those suffering from a cold. All I feel comfortable venturing beyond that is that there doesn't seem to be much in the way of non-anecdotal evidence that regular steam inhalation is particularly healthful, generally speaking. But if you have a symptom that you think a little steam would help alleviate (say, a cough) why not try it? Even better: ask a doctor.

* * *

Because I enjoy spending time in the steam-room, it would be fantastic if it also proved to be the key to an especially long and vigorous life. But unfortunately I have yet to be convinced that there is even a single substantial health benefit, beyond relaxation, directly associated with my steam-room habit. So when I see guys attempting to coax their reluctant girlfriends into the steam-room, or parents their children, with flippant promises that it will improve their health in some way, I often wonder how much thought preceded their statement.

(While I'm at it, there doesn't seem to be much evidence that you should compel yourself or others to follow a steam or sauna with an ice-cold shower or swim either, however invigorating or macho it may be to do so.)

Although these might, at first, seem like distinctly unimportant issues (after all, what's the harm in believing that your local rec center will admit you to the fountain of youth for only two dollars on week nights?), it should be appreciated that these opinions necessarily accompany mistaken assumptions about the way our bodies work, like the idea that sweat cleanses our bodies significantly, or that such things as "toxins" exist and must be consciously dealt with. And it can be really nice to know these things aren't true, especially when you don't like saunas or steam-rooms, or other alleged "detox" methods like the master cleanse (further discussed in this post), or mud-bathing.