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There is an age-old practice that's having a moment. We're talking about saunas. Enthusiasts cite a range of health benefits, as well as the bonding experience of sweating it out together. So what does the research tell us about this hot trend? NPR's Will Stone brings us this story.
(SOUNDBITE OF STEAM SIZZLING)
WILL STONE, BYLINE: If you want a sense of how saunas have captured the wellness zeitgeist, look no further than a sauna festival. They're popping up all over.
ANA HERNANDEZ: We have a very diverse group of saunas.
STONE: Ana Hernandez is one of the organizers at the first-ever Seattle Sauna Festival.
HERNANDEZ: So everything from a barrel sauna to a completely translucent sauna, a very traditional, custom-built Finnish-style sauna.
STONE: It's lively here on a Sunday morning. People pop in and out of saunas, steam rising off their bodies, occasionally subjecting themselves to an icy shower or dip in a tub.
MICHAEL CALCAGNO: Oh, in we go.
(SOUNDBITE OF WATER SPLASHING)
STONE: Michael Calcagno made the trip from Portland, Oregon, for the festival.
CALCAGNO: I came here because I love sauna. I think it's great for the body and the mind. It just feels like a womb, you know? You're just cradled in the warmth and the steam.
STONE: You hear a lot of people bring up the mental health benefits - relaxation, social connection. For Betsy Curran (ph), it's a way to tune out stress.
BETSY CURRAN: And I think that the people that are kind of exploring it are looking for refuge from our amped-up world.
STONE: Others like Jill Killen (ph) mention heart health.
JILL KILLEN: It kind of exercises your body in a different way.
STONE: Saunas are most closely tied to Northern Europe, though cultures around the world have used heat in one way or another for millennia. Traditional Finnish saunas are typically around 180 to just over 200 Fahrenheit.
CHRISTOPHER MINSON: There's very good evidence now that repeated use of heat is healthy for humans.
STONE: Christopher Minson is a physiologist at the University of Oregon who focuses on thermal regulation and health.
MINSON: We have this incredible ability to adapt to heat, and that really helped shape human evolution, much more than our ability to adapt to cold.
STONE: When you step inside that piping hot room, your cardiovascular system is put to the test. Your blood vessels dilate, heart rate increases, blood gets pushed to your skin where it can be cooled more easily as you sweat. Among the many effects, Minson says, repeated sauna use also increases what are known as heat shock proteins in your cells - these help combat inflammation. You also see improvements in blood pressure and cholesterol.
MINSON: So very similar to exercise, we have all these benefits.
STONE: Much of the research comes from Finland. Studies there find people who use the sauna frequently - four to seven times a week - have a significantly lower risk of cardiovascular disease and death. Dr. Setor Kunutsor, a researcher at the University of Manitoba in Canada, has been involved in much of this work.
SETOR KUNUTSOR: The evidence is robust, is consistent.
STONE: The improvements in cardiovascular health are the most well-studied, but Kunutsor and his colleagues have shown people who frequently go to the sauna are also less likely to develop respiratory illnesses and neurodegenerative diseases like Alzheimer's and dementia. He says the challenge now is doing larger well-controlled trials and not just in Finland.
KUNUTSOR: So we need to conduct a study in a population that has not engaged in sauna, you know, because sometimes it's very difficult to tease out an effect.
STONE: Many sauna enthusiasts keep coming back because of how it makes them feel. Dr. Charles Raison says this is what captured his interest years ago. He's a professor of human ecology and psychiatry at the University of Wisconsin-Madison.
CHARLES RAISON: High heat administered for a time-limited period is an antidepressant and a pretty good one.
STONE: Raison says the studies in this area are small, but the findings, compelling. They see that the hotter people get - up to a certain point - the more powerful the effect. In his studies, they actually cook people in a special machine with their head sticking out so their core temperature can get as high as a hundred and one. And he says there are plausible biological mechanisms here related to inflammation.
RAISON: And it turns out that the pathways in the brain and body that mediate thermoregulation overlap spectacularly with the pathways that mediate mood, desire, one's emotional state.
STONE: If you're new to sauna, the advice from Christopher Minson at the University of Oregon is go slow at first. Start with a 10- or 15-minute session, take breaks, and there are some people who do need to be careful. For example, if you have underlying heart conditions, check with a doctor. As for how hot you should get, Minson says, imagine a scale of 1 to 10.
MINSON: So zero is like, I am not hot at all, I am perfectly comfortable. And 10 is, I am on the surface of the sun, I'm the hottest I've ever been in my entire life. Like, I'm looking for a six to a seven.
STONE: Over time, he says, your body will adapt, and you can build up to 25 or 30 minutes. And if you can, ideally, try doing it in the company of others.
Will Stone, NPR News.
(SOUNDBITE OF HI-TEK SONG, "ALL I NEED IS YOU (FEAT. CORMEGA AND JONELL)") Transcript provided by NPR, Copyright NPR.
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