Sauna benefits: what the research actually says

People in Finland have been saying for centuries that the sauna is good for you. Over the last ten years, researchers have started to put numbers on it. Some of the claims hold up well. Others are wishful thinking.

Where the evidence comes from

Almost every headline about sauna and health traces back to one long-running project in eastern Finland, the Kuopio Ischaemic Heart Disease Risk Factor Study. In the 1980s, researchers recorded the habits of more than 2,000 middle-aged men from the region, including how often they used a sauna, then followed them for about 20 years.

That gives the research two strengths: lots of people, followed for a long time. It also comes with two limits worth keeping in mind:

• It shows links, not cause and effect. People who use a sauna every day might be healthier in other ways. The researchers adjusted for things like exercise, smoking and income, but no observational study can rule everything out.
• Most participants were Finnish men in traditional saunas. We know less about women, other countries and infrared saunas.

Heart health

This is where the evidence is strongest. In a 2015 paper in JAMA Internal Medicine, the Kuopio researchers looked at 2,315 men aged 42 to 60. Compared with men who used a sauna once a week:

• Men who went 2–3 times a week had a 22% lower risk of sudden cardiac death.
• Men who went 4–7 times a week had a 63% lower risk of sudden cardiac death and a 48% lower risk of dying from coronary heart disease.

Why might this happen? In a hot sauna your heart beats faster and your blood vessels widen, a bit like during light exercise. Done regularly, that may help keep blood vessels flexible. Researchers think this is part of the answer, though it hasn't been proven.

Blood pressure

Blood pressure usually drops for a while after a sauna, because the heat relaxes and widens your blood vessels. Later analyses of the same Finnish group found that men who used a sauna often were less likely to develop high blood pressure over the following years.

If you already take blood pressure medicine, that same drop can make you feel lightheaded when you stand up. Get up slowly, and check with your doctor if you're unsure.

Stroke and dementia

Two more results from the Kuopio study made headlines:

• Dementia. Men who used a sauna 4–7 times a week were 66% less likely to be diagnosed with dementia, and 65% less likely to be diagnosed with Alzheimer's disease, than men who went once a week.
• Stroke. A 2018 study of 1,628 men and women, published in Neurology, found that people who used a sauna 4–7 times a week had a 61% lower risk of stroke.

Both are striking numbers, and both come with the same caveat. They show that frequent sauna users had better outcomes, not that the sauna caused it. Still, the results line up with the heart findings, which makes them harder to wave away.

Muscles and recovery

A lot of athletes use the sauna after training, and many say they feel less stiff the next day. The research here is thinner: mostly small studies with a few dozen people. They suggest heat may ease muscle soreness a little and help people feel recovered, but the effects are modest. If it makes you feel good after a workout, that's a fine reason to go.

Sleep and stress

Ask regular sauna users why they go and "it helps me sleep" comes up a lot. There's a reasonable explanation: your body cools down after the heat, and falling body temperature is one of the signals that helps you fall asleep. Surveys of sauna users back this up, though there are few proper trials. The same goes for stress. Twenty quiet minutes somewhere with no phone is relaxing almost whatever the temperature.

What saunas don't do

• Weight loss. You can lose half a kilo or more in a session, but it's sweat. It comes straight back when you drink, and you should drink.
• Detox. Sweat is almost all water and salt. Your liver and kidneys remove waste from your body. Sweating barely adds to that.
• Curing colds. A sauna won't cure a cold, and it's a bad idea with a fever. Some research suggests regular users catch fewer colds, but the studies are small.

How to get the benefits

If you want to copy what the Finnish studies measured:

• Go often. The clearest benefits showed up in people who used a sauna at least 2–3 times a week, and more so at 4–7.
• Use a proper hot sauna. The studies looked at traditional Finnish saunas, which usually run at around 80 °C.
• Keep sessions moderate. Most people do rounds of 10–20 minutes. Our guide to how long to stay in a sauna covers this in detail.
• Cool down and drink water. A cold shower or plunge between rounds is traditional. A glass of water afterwards is essential.

Not sure which type of sauna to pick? Read sauna vs steam room and what is an infrared sauna.

Who should be careful

For most healthy adults a sauna is very safe. Check with a doctor first if you are pregnant, have a heart condition or unstable blood pressure, have recently had a heart attack or stroke, or take medicine that affects blood pressure or sweating. Never use a sauna after drinking alcohol, and leave if you feel dizzy, sick or confused.

This guide is general information, not medical advice.

Where to find a traditional sauna

Find My Sauna lists 2,311 places with a Finnish-style sauna. These cities have the most:

Lonnan sauna

Helsinki · Seaside sauna

Oslo Badstuforening Sukkerbiten

Oslo · Floating sauna

Rudas Gyógyfürdő és Uszoda

Budapest · Thermal bath and saunas

Frequently asked questions