The benefits of sauna
Regular sauna use has some of the strongest long-term research of any wellness habit. Here is what that research shows, what it does not, and how to get the most from your own sauna.
The science
What heat does to your body
Step into a traditional sauna and your body starts working to stay cool. Blood vessels in your skin widen, your heart beats faster to move blood to the surface, and you begin to sweat.
During a session, heart rate and blood pressure rise much as they do during moderate exercise. One study put the load on the heart at roughly the level of steady cycling (Ketelhut and Ketelhut, 2019). Afterwards, blood pressure settles below where it started. In a Finnish study of 102 adults, a single 30 minute session at 73°C lowered average blood pressure from 137/82 to 130/75 mmHg and made arteries less stiff (Laukkanen T. et al., 2018).
Repeat that a few times a week for years and the effects appear to add up. Most of what we know comes from one long-running Finnish study, which has followed the same group of people since the 1980s.
What the long-term research found
63%
lower risk of sudden cardiac death*
46%
lower risk of developing high blood pressure*
61%
lower risk of stroke*
66%
lower risk of dementia*
About these figures
*All four figures come from the Kuopio Ischaemic Heart Disease (KIHD) study at the University of Eastern Finland. They compare people who used a sauna 4 to 7 times a week with people who used one once a week, over follow-up periods of 15 to 25 years. The heart, blood pressure and dementia figures are from middle-aged men (Laukkanen T. et al., 2015 and 2017; Zaccardi et al., 2017). The stroke figure is from a group of men and women aged 53 to 74 (Kunutsor et al., 2018). These are observational studies. They show a strong link, not proof that the sauna caused the difference, and they are no substitute for medical advice.
What regular use is linked to
Sauna benefits, area by area
Heart and circulation
Lower blood pressure, healthier arteries
In the Finnish study, men who used a sauna 4 to 7 times a week had a 63% lower risk of sudden cardiac death than men who went once a week. They also had lower rates of fatal heart disease. A separate analysis found a 46% lower risk of developing high blood pressure. Longer sessions mattered too. Sessions of more than 19 minutes were linked with a lower risk of sudden cardiac death than sessions under 11 minutes. Researchers think the repeated rise in heart rate and the widening of blood vessels act as a gentle form of conditioning for the cardiovascular system.
Brain
Lower risk of dementia and stroke
The same Finnish men who used a sauna most often had a 66% lower risk of dementia and a 65% lower risk of Alzheimer’s disease. A later study, which included women, found a 61% lower risk of stroke at 4 to 7 sessions a week. Better blood pressure and blood vessel health are the most likely link, since both protect the brain as well as the heart.
Recovery and training
Heat after exercise
A sauna after training is a long-standing habit for athletes, and there is some evidence behind it. In a small study of six runners, three weeks of post-training sauna sessions raised plasma volume by 7% and extended how long they could run before exhaustion. That works out at roughly a 2% gain in a race. It is a promising result, not a guarantee. Our guides to sauna before and after workouts and sauna and cold plunge cover how to fit heat around training.
Other benefits researchers have looked at
The Global Sauna Survey asked 482 regular sauna users about their health. 83.5% said their sleep improved after a session. People who used a sauna 5 to 15 times a month also scored slightly higher on mental wellbeing than people who used one less often. This is self-reported, from people who already enjoy saunas, so treat it as a strong signal rather than proof. Our guide to sauna and mental health goes into more detail.
In the Finnish study, men who used a sauna 4 or more times a week had a 41% lower risk of lung conditions such as pneumonia, asthma and COPD. Men who went 2 to 3 times a week had a 27% lower risk. Warm air may help clear the airways, but the reason is not yet known.
Frequent sauna users in the Finnish study had lower levels of C-reactive protein, a marker of inflammation in the blood. The difference held 11 years later. Long-term inflammation is linked with heart disease, so this may be part of the explanation for the heart findings.
Men who used a sauna 4 to 7 times a week were less likely to die from any cause during the study than men who went once a week. The same study adjusted for age, weight, smoking, exercise and other factors, but people who use a sauna often may still be healthier in ways the researchers could not measure.
The pattern in the research
The benefits grew with the habit. More sessions each week, kept up over years, did more than any single hot one.
What a sauna does and does not do
Not in any meaningful way. Your liver and kidneys remove waste. Sweat is almost all water and salt, and studies measuring metals in sweat found only tiny amounts. Sweating feels cleansing, but it is not a detox.
You will weigh less after a session, but almost all of that is water, and it comes back when you drink. A sauna burns only a few more calories than sitting still. It can support a healthy routine, but it does not replace diet and exercise. See our guide to sauna and weight loss.
No. Heat raises your heart rate, but it does not build muscle or improve fitness the way training does. Use it alongside exercise, not instead of it.
Not automatically. Most of the research comes from one group of middle-aged Finnish men, and only the stroke study included women. Saunas are part of daily life in Finland, so the habit there is long and regular. The findings are consistent and well respected, but more research in other groups is still needed.
The large Finnish studies used traditional saunas. Infrared research is newer and smaller, though it has promising results of its own. Our guide to infrared saunas sets out what that research shows.
Safety
Is a sauna safe?
For most healthy adults, yes. A review of 40 clinical studies found regular sauna use was well tolerated, and the side effects reported in the Global Sauna Survey were mostly minor, such as dizziness, headache or feeling dehydrated. A 24 year Finnish study found sauna use did not increase or decrease the risk of cancer.
The main risks come from how a sauna is used. Alcohol is the biggest one, and most deaths in saunas in Finland involved alcohol. Stay hydrated, stand up slowly and leave if you feel unwell.
Safety in detail
Speak to your GP before using a sauna if you are pregnant, have a heart condition, have recently had a heart attack, have low blood pressure, or take medication that affects your blood pressure or how you handle heat.
No. Alcohol lowers blood pressure and dulls your sense of overheating, which is why it features in most serious sauna incidents. Wait until it has fully worn off.
Skip it if you have a fever or feel unwell. The heat adds strain your body does not need. Our guide to when it is best to skip the sauna covers the details.
Children overheat faster than adults. Keep sessions short and cooler, and always supervise them.
Same benefits, different heat
Infrared or traditional?
Traditional
158 to 194°F
Shorter, more intense
Heats the air around you. The long-term Finnish research used traditional saunas.
Infrared
113 to 140°F
Longer, gentler sit
Warms you directly rather than the air. The science is younger, with promising findings of its own.
Sauna benefits FAQs
For most healthy adults, yes. Long-term Finnish research links regular sauna use with a lower risk of heart disease, high blood pressure, stroke and dementia. The biggest benefits were in people who used a sauna 4 to 7 times a week. Check with your GP first if you are pregnant or have a heart condition.
The strongest results in the research were at 4 to 7 sessions a week. Some benefits, such as a lower risk of lung conditions, also appeared at 2 to 3 sessions. Regular use matters more than very long or very hot sessions.
Most people do well with 15 to 20 minutes in a traditional sauna. In the Finnish study, sessions of more than 19 minutes were linked with lower heart risk than sessions under 11 minutes. Build up to that gradually, and leave whenever you feel uncomfortable.
Blood pressure rises during a session, then drops below its starting level afterwards. In one study, a single 30 minute session lowered it from 137/82 to 130/75 mmHg on average. Over the long term, men who used a sauna 4 to 7 times a week had a 46% lower risk of developing high blood pressure.
There is some evidence it helps. A small study of runners found post-training sauna sessions raised plasma volume and improved endurance by about 2% in race terms. See our guide to sauna around workouts.
Many people find it does. In the Global Sauna Survey, 83.5% of regular users said their sleep improved after a session. The gentle drop in body temperature afterwards is a natural cue for sleep.
Heat sends more blood to the skin, which is why you leave a session flushed, and sweating rinses the surface. That is about where the evidence stops. Pores are not muscles, so they do not open and close, and sweat does not carry meaningful toxins out through them. Shower once you have cooled down, and go gently if you have eczema or rosacea, since heat can aggravate both.
Most of the Finnish research studied men. The stroke study included women aged 53 to 74 and found the same benefit for both sexes. There is no evidence that women benefit less, but there is less research.
Sources
- Laukkanen T. et al. (2015). Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine. Read the study
- Laukkanen T. et al. (2017). Sauna bathing is inversely associated with dementia and Alzheimer’s disease in middle-aged Finnish men. Age and Ageing. Read the study
- Zaccardi F. et al. (2017). Sauna bathing and incident hypertension: a prospective cohort study. American Journal of Hypertension. Read the study
- Kunutsor S.K. et al. (2018). Sauna bathing reduces the risk of stroke in Finnish men and women: a prospective cohort study. Neurology. Read the study
- Kunutsor S.K. et al. (2017). Sauna bathing reduces the risk of respiratory diseases: a long-term prospective cohort study. European Journal of Epidemiology. Read the study
- Kunutsor S.K. et al. (2018). Longitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort study. Annals of Medicine. Read the study
- Laukkanen T. et al. (2018). Acute effects of sauna bathing on cardiovascular function. Journal of Human Hypertension. Read the study
- Ketelhut S. and Ketelhut R.G. (2019). The blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exercise. Complementary Therapies in Medicine. Read the study
- Laukkanen J.A. et al. (2018). Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings. Read the study
- Hussain J. and Cohen M. (2018). Clinical effects of regular dry sauna bathing: a systematic review. Evidence-Based Complementary and Alternative Medicine. Read the study
- Hussain J.N. et al. (2019). A hot topic for health: results of the Global Sauna Survey. Complementary Therapies in Medicine. Read the study
- Scoon G.S.M. et al. (2007). Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport. Read the study
- Laukkanen J.A. et al. (2019). Finnish sauna bathing does not increase or decrease the risk of cancer in men: a prospective cohort study. European Journal of Cancer. Read the study
- Kenttämies A. and Karkola K. (2008). Death in sauna. Journal of Forensic Sciences. Read the study
- Kuan W.H. et al. (2022). Excretion of Ni, Pb, Cu, As, and Hg in sweat under two sweating conditions. International Journal of Environmental Research and Public Health. Read the study
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