The Science
What does the research say sauna does for your health?
Finnish studies link frequent sauna with fewer heart deaths and less dementia in middle-aged men. They show an association, and no trial has tested it.
The best long-term evidence comes from a Finnish study that followed men in eastern Finland for about 20 years, and it found that those who took saunas most often died of heart disease less and developed dementia less. That's an association in an observational study of Finnish men. No randomized trial has tested whether sauna prevents heart disease or dementia, and the people who bathe four times a week may differ in other ways from those who bathe once. We read each study the site cites, from the abstracts and, where open, the full papers, and we say who was studied and how.
One cohort of Finnish men supplies most of the evidence
The Kuopio Ischaemic Heart Disease Risk Factor Study enrolled men aged 42 to 60 in eastern Finland in the 1980s and asked them once how often they took a sauna. Researchers then followed them for decades. The rooms were traditional Finnish saunas with dry air, at a reported average of about 174°F (79°C), per the 2015 JAMA paper.
That design matters for everything below. It's observational, so it can find links and can't prove cause, and most of its papers studied men only. The authors themselves list residual confounding and reverse causation among the limits.
| Study | Who | Follow-up (median) | 4–7 sessions vs 1 a week |
|---|---|---|---|
| JAMA Internal Medicine, 2015 | 2,315 men aged 42–60 | 20.7 years | Sudden cardiac death HR 0.37 |
| Age and Ageing, 2017 | 2,315 men aged 42–60 | 20.7 years | Dementia HR 0.34 |
| American Journal of Hypertension, 2017 | 1,621 men without hypertension | 24.7 years | High blood pressure HR 0.53 |
| Respiratory Medicine, 2017 | 2,210 men aged 42–61 | 25.6 years | Pneumonia HR 0.56 (4+ sessions) |
| Neurology, 2018 | 1,628 men and women aged 53–74 | 14.9 years | Stroke HR 0.39 |
| BMC Medicine, 2018 | 1,688 men and women aged 53–74 | 15.0 years | Fatal heart disease HR 0.23 |
Hazard ratios as each abstract reports them, after the authors' adjustments; below 1 means lower risk than the once-a-week group. All are observational associations. Read Oct 10, 2026.
Frequent bathers had fewer heart deaths
In the JAMA study, men who used a sauna four to seven times a week had a hazard ratio for sudden cardiac death of 0.37 against men who went once, about a third the risk. Longer sessions, over 19 minutes, were linked with fewer fatal heart events than sessions under 11 minutes. Two later papers found the link held alongside fitness: men who were both fit and frequent bathers fared best, per Annals of Medicine.
The authors call for studies in women and say their results at about 174°F (79°C) don't carry over to steam rooms.
The same men developed dementia less often
Among the same 2,315 men, those who took four to seven saunas a week had a hazard ratio for dementia of 0.34 and for Alzheimer's disease of 0.35, compared with once a week, per Age and Ageing. At two to three sessions, the figures weren't statistically clear. The authors say more studies are needed to find any mechanism.
Blood pressure, pneumonia and stroke followed the same pattern
Men without high blood pressure at the start who bathed four to seven times a week developed it less over about 25 years, per the American Journal of Hypertension. Frequent bathers were also diagnosed with pneumonia less, per Respiratory Medicine, a finding its authors limit to middle-aged white men.
Women joined the cohort later. The stroke study of 1,628 men and women aged 53 to 74 found a hazard ratio of 0.39 for the most frequent bathers. In the BMC Medicine study of the same later group, the women-only analysis showed no statistically significant link, which the authors put down mostly to how few women had events.
None of this shows that sauna caused it
These are associations, and the studies can't tell whether sauna did the work. A 2018 systematic review of 40 clinical studies says the mortality link "may be noncausal" and that frequent bathing may mark a healthier way of life. Only 13 of those 40 studies were randomized, and most had fewer than 40 people.
The Finnish men also lived where sauna is ordinary. The BMC Medicine authors ask for studies in people who aren't used to regular bathing, which describes most Americans.
Infrared has thinner evidence
A 2009 review of far-infrared saunas called the evidence "limited," with some support for blood pressure and heart failure and evidence against claims about cholesterol. A Japanese trial gave 149 hospitalized patients with advanced heart failure a far-infrared session at about 140°F (60°C) daily for 10 days. Their symptoms and walking distance improved, and the trial's main blood marker didn't move enough to count.
None of the Finnish cohort findings come from infrared cabins, so they don't transfer.
Athletes have a few small studies
Six male distance runners who took a humid sauna after training for three weeks ran 32% longer to exhaustion, per the Journal of Science and Medicine in Sport, likely through more blood volume. A single 30-minute heat session in 25 young adults raised heart rate and lowered systolic blood pressure, per the Journal of Athletic Training. Both are small and short.
Some people should skip the sauna
A 2001 review00671-9/fulltext) in The American Journal of Medicine lists unstable angina, a recent heart attack and severe aortic stenosis as reasons not to bathe, and calls sauna safe for most people with stable angina or an old heart attack. It says alcohol in the sauna raises the risk of low blood pressure, arrhythmia and sudden death. Ask your doctor first if you have a heart condition.
How we read these studies
We read the PubMed abstract of every study above and the full open-access text of the BMC Medicine, European Journal of Epidemiology and systematic-review papers, on Oct 10, 2026. Figures are quoted as the papers report them. None of this is medical advice.
Common questions
- Does sauna lower the risk of heart disease?
- In a Finnish cohort of 2,315 middle-aged men, those who used a sauna four to seven times a week had a hazard ratio for sudden cardiac death of 0.37 compared with once a week. It's an observational association, and no randomized trial has tested whether sauna prevents heart disease.
- How many times a week should you use a sauna?
- The Finnish studies compared one, two to three and four to seven sessions a week, and the strongest associations were at four to seven. They don't prescribe a number, and a 2018 systematic review says the best frequency and length still need study.
- Are infrared saunas as healthy as traditional saunas?
- The long-term Finnish findings all come from traditional saunas, and none from infrared cabins. A 2009 review called the evidence for far-infrared saunas limited, with some support for blood pressure and heart failure and evidence against cholesterol claims.
- Who shouldn't use a sauna?
- A 2001 review in The American Journal of Medicine lists unstable angina, a recent heart attack and severe aortic stenosis as reasons not to use a sauna, and says to avoid alcohol while bathing. Anyone with a heart condition should ask a doctor first.
Sources
- 1.Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine, 2015.
- 2.Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men. Age and Ageing, 2017.
- 3.Sauna Bathing and Incident Hypertension: A Prospective Cohort Study. American Journal of Hypertension, 2017.
- 4.Sauna bathing reduces the risk of stroke in Finnish men and women. Neurology, 2018.
- 5.Frequent sauna bathing may reduce the risk of pneumonia in middle-aged Caucasian men: The KIHD prospective cohort study. Respiratory Medicine, 2017.
- 6.Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC Medicine, 2018.
- 7.Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study. Annals of Medicine, 2018.
- 8.Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review. Evidence-Based Complementary and Alternative Medicine, 2018.
- 9.Benefits and risks of sauna bathing. The American Journal of Medicine, 2001.
- 10.Far-infrared saunas for treatment of cardiovascular risk factors. Canadian Family Physician, 2009.
- 11.Waon Therapy for Managing Chronic Heart Failure: Results From a Multicenter Prospective Randomized WAON-CHF Study. Circulation Journal, 2016.
- 12.Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport, 2007.
- 13.Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans. Journal of Athletic Training, 2012.
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