What the research says about sauna

The best-known sauna study followed 2,315 men aged 42 to 60 in eastern Finland for about 20 years. Compared with men who used a sauna once a week, men who went 4 to 7 times a week had a 63% lower risk of sudden cardiac death, after adjusting for other heart risk factors. They were also less likely to die of heart disease or of any cause. Sessions longer than 19 minutes were linked to lower risk too.

That's a link, not proof. Men who use a sauna almost daily may differ in ways the study couldn't measure. Only 201 men were in the most frequent group, all of them were men, and most later sauna research comes from the same Finnish group. Treat the numbers as promising, not settled. Ageon tags sauna as moderate evidence and gives it 2 points.

Sauna is safe for most healthy adults. Skip it if you have unstable angina, a recent heart attack or severe aortic stenosis. Don't drink alcohol before or during a session, because it raises the risk of low blood pressure, an irregular heartbeat and sudden death. Drink water, and get out if you feel dizzy.