Sauna 4 to 7 Times a Week Linked to 77% Lower Risk of Heart Death

Saunas are having a moment, from gyms to wellness feeds.

In Finland, they’re simply part of life. That’s handy for science, because Finland has decades of data on people who sit in very hot rooms.

So is sauna actually good for you? The answer is more interesting than yes or no.

Is sauna good for you?

Probably, for your heart. But the strongest evidence comes from Finland, and it shows a link, not proof.

The research here is about the traditional Finnish sauna. That’s a hot, dry wooden room, usually around 80 °C (176 °F).

In the main study below, the average sauna was about 76 °C (169 °F). A typical session lasts 5 to 20 minutes.

Steam rooms are cooler and more humid. The researchers say their findings can’t be directly applied to them.

What the research shows

A 15-year study of 1,688 Finnish adults

The main study is a 2018 paper in BMC Medicine. Researchers asked 1,688 adults in eastern Finland how often they used a sauna.

The group was aged 53 to 74, and about half were women. The team then followed them for about 15 years.

During that time, 181 people died of cardiovascular disease. That includes deaths from heart attacks and strokes.

Heart deaths fell as sauna use rose

The more often people used a sauna, the fewer died of cardiovascular disease.

The researchers then took other factors into account. These included age, sex, smoking, blood pressure, cholesterol, alcohol, exercise and income.

After that, people who used a sauna 4 to 7 times a week had a 77% lower risk than once-a-week users.

For 2 to 3 sessions a week, the risk was 25% lower. But that result wasn’t statistically certain.

The catch: who uses the sauna most

This is the part I’d keep in mind. The most frequent sauna users were different from the others before the study began.

They were younger on average, 60 versus 64. And 64% were men, compared with 39% of the once-a-week group.

The researchers adjusted for these differences. Still, they warn there is “a potential for residual confounding”, meaning other hidden differences could explain part of the link.

There’s also a numbers problem. Only 8 people in the 4-to-7 group died of cardiovascular disease, so the true effect could be much smaller.

And in women alone, there was no clear link. Among the 73 women in the top group, no one died of cardiovascular disease, which made the math unreliable.

Who funded it

The study was funded by the Finnish Foundation for Cardiovascular Research. The authors declared no competing interests.

The newest research

An 8-week trial: sauna on top of exercise

Studies that follow people can’t prove cause. For that, you need a trial where people are randomly assigned.

A 2022 trial in the American Journal of Physiology did just that. It included 47 inactive adults, aged 49 on average, each with at least one heart risk factor.

People were split into three groups. One did exercise plus a 15-minute sauna afterwards, one did exercise only, and one made no changes.

Both exercise groups trained three times a week for 8 weeks. The sauna started at 65 °C and rose by 5 °C every two weeks.

What adding the sauna changed

Here’s how exercise plus sauna compared with exercise alone:

But exercise did the heavy lifting for fitness. Compared with doing nothing, exercise alone raised fitness by 6.2 points.

The limits of this trial

The trial was small and short. Almost everyone was a woman, with only 6 men.

There was also no sauna-only group. So it can’t tell us whether sauna works without exercise.

Diet wasn’t controlled either. The trial was funded in part by the Finnish Cultural Foundation, and the authors declared no conflicts.

What earlier research found

The first big study: 2,315 Finnish men

The 2018 study built on a 2015 paper in JAMA Internal Medicine. It followed 2,315 middle-aged Finnish men for about 21 years.

Among men who used a sauna once a week, 22.3% died of cardiovascular disease. Among those who went 4 to 7 times a week, it was 12.0%.

Deaths from any cause showed a similar pattern: 49.1% versus 30.8%.

After adjusting for other risk factors, frequent users had a 63% lower risk of sudden cardiac death. Longer sessions, over 19 minutes, were also linked to lower risk.

Sauna and dementia

A 2020 study in Preventive Medicine Reports followed 13,994 Finnish adults for 39 years. In that time, 1,805 were diagnosed with dementia.

People who used a sauna 9 to 12 times a month had a 19% lower risk than those who went less than 4 times.

But two details stood out to me. People who went even more often, 13 to 30 times a month, had no lower risk.

And very hot saunas, 100 °C or more, were linked to about twice the dementia risk in the first 20 years. That was compared with saunas under 80 °C.

A review of 40 studies

A 2018 review in Evidence-Based Complementary and Alternative Medicine pulled together 40 studies with 3,855 people.

Most reported benefits. But only 13 were randomised trials, and most included fewer than 40 people.

The review found one clear downside. In a small study of 10 men, two 15-minute saunas a week for 3 months cut sperm counts by more than half.

The good news: sperm counts were back to normal 6 months after the men stopped. The review’s verdict was that sauna “has potential health benefits”.

Who should be careful

A 2001 review in The American Journal of Medicine looked at sauna safety. It found sauna is well tolerated by most healthy adults.

It is not safe after a recent heart attack or with unstable chest pain (angina). The same goes for severe narrowing of the heart’s main valve (aortic stenosis).

Most people with stable heart disease can use a sauna safely, the review says. But alcohol in the sauna raises the risk of low blood pressure, irregular heartbeat and sudden death.

How it fits together

Two long Finnish studies point the same way, and a small trial suggests one reason why: lower blood pressure.

How much should you trust this?

Early. The links are strong and consistent, but they come from observational studies in Finland. The only trial was small and short.

What makes it convincing

• People were followed for 15 to 39 years, with no losses to follow-up in the main study.
• Risk fell steadily as sauna use rose, which is what you’d expect from a real effect.
• Two Finnish studies, started years apart, found similar links with heart deaths.
• A randomised trial found a plausible reason: lower blood pressure.

What makes me cautious

• Frequent sauna users were younger and more often men, and hidden differences may remain.
• Only 8 heart deaths occurred in the most frequent group.
• The main study, the 2015 study and the trial all come from the same research group.
• Nearly all the data come from traditional Finnish saunas, not steam rooms or infrared saunas.

What this means for you

• Enjoy it, if you like it. For most healthy adults, a sauna looks safe and may help the heart.
• Keep sessions moderate. Typical Finnish sessions last 5 to 20 minutes. Very hot saunas, 100 °C or more, were linked to higher dementia risk in one study.
• Skip the alcohol. Drinking in the sauna raises the risk of low blood pressure and heart rhythm problems.
• Don’t swap it for exercise. In the trial, sauna was added to exercise, and exercise did more for fitness.
• Have a heart condition? Talk to your doctor first, especially after a recent heart attack or with unstable chest pain.
• Trying for a baby? Regular sauna can lower sperm counts for a few months.
• Pregnant? Ask your midwife or doctor before using a sauna.

Get out and cool down if you feel dizzy, sick or get a headache. The NHS guide to heat exhaustion lists the signs and what to do.

In this interview on the FoundMyFitness podcast, Jari Laukkanen, the senior author of the main study, explains the Finnish sauna research:

What we still don’t know

1. Does sauna itself cause the benefit? Only a long randomised trial could show that, and none exists yet.
2. Do steam rooms and infrared saunas work the same way? They work differently, and they’ve barely been studied for long-term health.
3. What’s the best dose? The studies suggest frequent sessions, but the ideal heat and length are unclear.
4. Does it work outside Finland? Most long-term data come from Finns who grew up with saunas.

My take: a pleasant habit with a possible heart bonus

What I like about this research is its length. Following people for 15 years or more is rare, and the pattern is striking.

I’m less convinced by claims that sauna is a cure-all. The best data show a link, and the people who use saunas most may simply be healthier to begin with.

So my reading is simple. If you enjoy a sauna, keep going, and skip the beer.

Just don’t treat it as a replacement for exercise. The workout still matters more.