For years, the strongest evidence linking regular sauna use to a healthier heart came from Finnish research on middle-aged men. A separate prospective cohort of 1,688 adults, more than half of them women, has since offered an answer to the obvious follow-up question. Does the same protection apply to women?
The study, published in November 2018 in BMC Medicine, followed participants for a median of 15 years. It found that the risk of cardiovascular disease mortality fell linearly as weekly sauna sessions increased, and that the association was not significantly different between the sexes.
Compared with people who used the sauna once a week, those visiting four to seven times a week had roughly a quarter of the fatal CVD rate after full adjustment. The mortality rate among the most frequent bathers was 2.7 per 1,000 person-years, against 10.1 in the once-weekly group.
A 2018 review in Mayo Clinic Proceedings by the same research group concluded that regular sauna use is linked to improvements in blood vessel function, lower arterial stiffness, and reduced blood pressure. The paper places these vascular effects in the same broad family as those produced by moderate exercise.
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How the heat helps the heart
Sitting in a hot, dry room raises heart rate and pushes cardiac output up by as much as 60 to 70 percent without a large jump in stroke volume, according to a 2025 review in Frontiers in Cardiovascular Medicine. Blood vessels widen, endothelial function improves, and blood pressure typically falls after a session.
The mechanism appears to be a mild stress response. Repeated heat exposure switches on protective cellular pathways, including heat shock proteins and nitric oxide signaling in the vessel wall.
How often, how long, how hot
Studies that report cardiovascular benefits describe short, frequent sessions rather than long ones. The Frontiers review puts the typical protocol at 5 to 20 minutes per visit, 2 to 4 times per week, in a room at 80 to 100°C with low humidity.
The steepest drop in cardiovascular mortality in the Finnish cohort was seen in people who bathed four to seven times a week. In practice, that means most days of the week, for a short stay.
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Who should skip it
Not everyone should use a sauna. Stanford Lifestyle Medicine advises caution or a doctor's clearance for people with unstable angina or a recent heart attack, arrhythmias, heart failure with a low ejection fraction, poorly controlled hypertension, pregnancy or breastfeeding, severe diabetes, kidney disease, or epilepsy.
The Stanford team also flags a simple in-session rule. Step out immediately if you feel lightheaded, dizzy, nauseated, or notice unusual heart sensations. Anyone with a chronic condition or on medication that affects body temperature should talk with their doctor before starting a routine.
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