Does sauna add years?

The 201 men in the 4-to-7 group were 40% less likely to die of any cause over 20.7 years than the 601 once-a-week men, after adjusting for age, smoking, blood pressure, cholesterol, diabetes, fitness, alcohol and more (hazard ratio 0.60, Laukkanen et al. [1]). Fatal heart and vessel disease was 50% lower and sudden cardiac death 63% lower. Your Health Score credits this answer 5.9 years, the study’s hazard ratio translated straight into years (8 × log2 of the hazard ratio); see item 7 for the caveats to weigh, not subtract.

This was the biggest group, 1,513 men, and it still showed 24% lower all-cause mortality (hazard ratio 0.76, 95% confidence interval 0.66 to 0.88) and 27% lower fatal heart and vessel disease than once a week [1]. The confidence interval is tight because the group is large, which is why this is the best-supported single number on the page. YapSpan credits it 3.2 years, the same hazard-ratio-to-years translation as the 4-to-7 band.

Men whose sessions ran longer than 19 minutes had 52% lower sudden cardiac death risk than men who stayed under 11 minutes (hazard ratio 0.48, [1]). Counting weekly minutes instead, more than 45 minutes a week meant 43% lower heart-related death risk than 15 minutes or less (hazard ratio 0.57, [5]). Typical Finnish practice is 80 to 100 °C, 10 to 20 minutes, with a cool-down and a second round.

In the same men, dementia was 66% less common and Alzheimer’s disease 65% less common in the 4-to-7 group than the once-a-week group (hazard ratios 0.34 and 0.35, Laukkanen et al. [2]). With women added and stroke as the outcome, 2 to 3 sessions meant 14% lower risk and 4 to 7 sessions 61% lower [3]. These are not counted separately on your Health Score, because a habit that lowers death from heart disease and stroke is already credited in the years above.

Over 24.7 years, men who saunaed 4 to 7 times a week were 46% less likely to develop high blood pressure than once-a-week men (hazard ratio 0.54; 2 to 3 times, hazard ratio 0.76, Zaccardi et al. [4]). A sauna session lifts heart rate to 100 to 150 beats a minute and roughly doubles the blood the heart pumps, then blood pressure drops below baseline for hours afterwards, which is the plausible mechanism [7].

The cohort measured fitness directly, on a treadmill. Splitting the men by fitness and sauna frequency, those with both high fitness and 3 to 7 saunas a week had the lowest heart-related and all-cause death risk, and the sauna effect held after adjusting for fitness [6]. But fit men who rarely saunaed did better than unfit men who saunaed often. A sauna raises heart rate without training your muscles or lungs.

A hazard ratio of 0.60 for death translates to 5.9 years of life expectancy (8 × log2 of the ratio); 0.76 translates to 3.2. YapSpan credits both figures as published, not cut down, because the arithmetic is the study’s own. What to weigh instead: everything here is one observational cohort in one country, the death numbers are men only, the 4-to-7 group is 201 people, there is no randomised trial with death as the outcome, and Finns who sauna daily also tend to be wealthier, fitter and more socially connected, all of which lengthen life on their own. Those are the classic reasons an observed effect shrinks when it is finally tested properly — reasons to read the number with care, not a formula for shrinking it ourselves.

In 30,000 Japanese adults followed for 19 years, bathing in a hot tub almost every day was associated with 28% lower risk of heart and vessel disease than two times a week or less (hazard ratio 0.72, Ukai et al. [8]), with similar drops for heart attack and stroke. It is the same kind of evidence as the sauna studies, with the same caveats, and points the same way.

In the Finnish data, sauna deaths are rare and almost all involve alcohol, being alone, or a recent heart event [7]. Heat plus alcohol drops blood pressure and impairs judgement at the same time. Unstable angina, a heart attack in the last few weeks, severe aortic stenosis and uncontrolled blood pressure are the recognised reasons to wait for a doctor’s go-ahead. Well-managed stable heart disease is not, and small trials in heart failure patients have been reassuring.

Every number above comes from a hot, dry Finnish sauna with steam bursts off the rocks (löyly), typically 80 to 100°C, and the review behind those numbers says its findings "cannot be directly applied" to other heat modalities [7]. Infrared cabins run cooler, usually 45 to 60°C, and heat the body directly rather than the air, but a small 2026 trial found 65°C infrared raised core temperature about as much as a traditional session (+1.4°C in 12 adults), so the acute heat stress can overlap [9]. What has not been shown is the same payoff: a crossover trial of 10 women found no detectable change in blood pressure, arterial stiffness or heart-rate variability after a single infrared session [10], and a 2025 review of infrared and heart disease found its evidence mostly in small heart-failure trials on endothelial function and symptoms, not death, explicitly noting the evidence base is smaller than for Finnish saunas with no mortality data of its own [11]. Steam rooms are studied less still: the Mayo Clinic Proceedings review says the same thing about them directly, that humid, lower-heat bathing "cannot be directly applied" to the Finnish findings, and no cohort has followed steam-room users the way KIHD followed sauna-goers.