Why do I stay so much warmer after a sauna compared with a steam room?

January 13, 2022 5:30 AM

What I observe is that after going from a steam room to a cold locker room, I get chilled within a minute, but after leaving a sauna, my body feels warm for a few hours. Just curious on the physics behind this (perhaps just the fact that sauna's are hotter).

Being in the steam room does feel hot, but is there something with the moisture that keeps the heat at the skin level? Does IR heat from sauna coils/rocks penetrate deeper?

posted by Jon44 to Health & Fitness (7 answers total)

Having water on your skin makes you lose heat faster (that's why we sweat when we're too hot). I'd imagine your skin has a lot more moisture on/in it when you leave a steam room, which makes you cool much quicker.
posted by penguin pie at 5:58 AM on January 13, 2022 [4 favorites]

The water evaporating off off your skin cools you off. When you depart from a sauna you are very dry.
posted by waving at 6:05 AM on January 13, 2022 [1 favorite]

Response by poster: P.s., I don't think it's evaporative cooling, as I sweat a lot in a sauna as well and the moisture on the skin, in both cases, evaporates pretty quickly. (Plus, I notice the same longer-term effects even if I go immediately to a shower from either room.)
posted by Jon44 at 6:20 AM on January 13, 2022 [2 favorites]

This is a total guess, but since hot water (vapor) transmits heat into your body more effectively than hot, dry air alone, your body may be kicking into a relatively overclocked cooling response during a steam than during the same amount of time in a dry sauna. Put another way, it's evaporative cooling in the other direction. You hammer so much heat into your body during a steam bath that you've got much more to shed when you equilibrate when back at room temperature.

The physiology of heat shedding isn't only evaporative cooling from sweat. It's also, for example, how perfused your skin is to allow more heat to escape from that huge surface area. It's been a long time since I paid attention to physiology, but I also imagine there's a respiratory element to thermoregulatory homeostasis--do you notice that you're breathing more deeply or more rapidly after a steam than after a dry sauna? I hope there are some physiologists out there who weigh in on this, I'm fascinated by whether this is a widely observed phenomenon or something that's idiosyncratic. Cool question!
posted by late afternoon dreaming hotel at 7:03 AM on January 13, 2022 [2 favorites]

Could it just be the difference in temperature? A steam room is usually 110-120ish and a sauna 140 and up.
posted by InkaLomax at 8:03 AM on January 13, 2022 [2 favorites]

In a steam room your skin absorbs water, but in a sauna your skin dries out, and my experience is that sweat glands or some accessory gland also produce lipids which limit the extent of water absorption by skin, then when you come out of the steam bath that water evaporates and you’re cold.
posted by jamjam at 10:08 AM on January 13, 2022 [2 favorites]

If you feel the effect hours later, it is probably not a result of the sauna heat penetrating deeper. Something about the sauna experience is changing your internal metabolism. Maybe your outer blood vessels are expanding, so you feel warmer (same as if you drink alcohol), or your metabolism is ramping up and you're producing more heat internally. I get sweaty if I drink too much coffee, regardless of whether the coffee is piping hot or room temp. I also feel warmer in general for a while after taking a steamy shower. Sadly I haven't had access to a dry sauna and steam room since covid hit, so I can't add more personal data :)
posted by mrgoldenbrown at 11:05 AM on January 13, 2022 [1 favorite]