Why Sitting in Extreme Heat Might Be One of the Best Things You Do for Your Body

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For most people, a sauna is a place to relax after a workout or unwind with friends. But a growing body of research suggests that the heat itself is doing far more than helping you sweat. Long-term studies from Finland, where sauna bathing is a daily ritual for millions, have linked frequent sauna use to lower rates of heart disease, stroke, dementia, and death from any cause.

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A Simple Habit With Measurable Effects

The most influential evidence comes from the Kuopio Ischaemic Heart Disease Risk Factor Study, which has tracked thousands of Finnish men and women for more than two decades. Researchers led by Dr. Jari Laukkanen at the University of Eastern Finland found that among 2,315 middle-aged men followed for a median of nearly 21 years, those who used the sauna more often had fewer sudden cardiac deaths, fewer fatal heart attacks, and fewer deaths overall.

The difference in risk was substantial. Compared with men who took one sauna session per week, those who went two to three times a week cut their risk of sudden cardiac death by 22 percent, and those who went four to seven times a week cut it by 63 percent. The pattern held up even after researchers adjusted for other health and lifestyle factors.

An editorial accompanying the study, written by JAMA Internal Medicine editor-in-chief Dr. Rita Redberg, put it simply: whatever the reason — the heat itself, the relaxation, or the social time spent with others — time in the sauna appeared to be time well spent.

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Lower Stroke Risk, Too

A separate study published in Neurology, again drawing on the same Finnish cohort, looked specifically at stroke. Following 1,628 men and women for a median of nearly 15 years, researchers recorded 155 strokes and found that people who used the sauna four to seven times a week had a 61 percent lower risk of stroke than those who went just once a week.

Study author Dr. Setor Kunutsor of the University of Bristol noted that previous research had already linked sauna bathing to lower rates of high blood pressure, dementia, and cardiovascular death, but this was the first study to connect it specifically to stroke risk. He added that saunas appear to lower blood pressure, which may explain part of the protective effect.

It's worth noting, as Kunutsor pointed out, that the study only shows an association, not proof that sauna use directly causes the lower risk, and the findings are based specifically on traditional Finnish-style saunas rather than infrared heat or steam rooms.

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What's Actually Happening Inside the Body

Researchers believe the effects come down to how the body responds to heat stress. Sitting in a hot room raises core temperature, speeds up the heart, and widens blood vessels — a response that shares some features with moderate exercise. Over time, repeated exposure appears to train the cardiovascular system to handle stress more efficiently, similar to how regular workouts build fitness.

A 2022 follow-up study from the same Finnish research group looked at inflammation specifically. Tracking 2,575 men over a median of nearly 28 years, the researchers found that both high inflammation levels and low frequency of sauna use were separately linked to a higher risk of death — suggesting sauna bathing may help offset some of the damage caused by chronic inflammation.

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Not a Substitute for Exercise

None of this means saunas can replace physical activity. Exercise builds muscle, strengthens bones, and puts mechanical load on the body in ways that passive heat cannot replicate. Most researchers in this field describe sauna bathing as a complement to a healthy lifestyle rather than a replacement for it.

The studies are also observational, meaning they show a strong statistical link rather than definitive proof of cause and effect. People who use saunas frequently in Finland may also share other habits or social circumstances that support long-term health. Still, the consistency of the findings across multiple independent studies — covering heart disease, stroke, and inflammation — has made sauna bathing a genuine subject of interest for cardiovascular researchers, not just a wellness trend.

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Looking Ahead

Interest in heat therapy has grown well beyond Finland in recent years, with infrared saunas and heat-based wellness treatments becoming popular in gyms and spas worldwide. Researchers caution that most of the strongest evidence still comes specifically from traditional Finnish sauna use — hot, dry heat sessions of around 15 to 20 minutes, several times a week — and that other forms of heat exposure haven't been studied as extensively.

For now, the advice from the scientists behind these studies is straightforward: sauna bathing appears to be a low-risk habit with a plausible long-term payoff for heart and brain health, best used alongside — not instead of — regular exercise and a balanced lifestyle.

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