The Science · Interactive
Meet the 2,315 Finnish men behind the headlines about saunas and longevity
The best-known sauna study followed men from one Finnish town for more than twenty years.1 Its numbers now turn up on podcasts and on the product pages of sauna brands. Scroll through the men one ember at a time to see where they come from.
It starts in Kuopio in 1984
A heart study in eastern Finland asked 2,327 men how often they took a sauna
Researchers recruited middle-aged men from Kuopio and the surrounding countryside between 1984 and 1989, and each man filled in a questionnaire about his sauna habits.1 Every point of light on this page is one of those men.
Nearly all of them took saunas
Twelve men never took saunas, so the study left them out
That left 2,315 men and no comparison group of people who avoid the sauna. Every result from here on compares frequent bathers with men who went once a week.1
Their answers set the groups
The men split into three groups by how often they went
Weekly bathers made up 601 of the men, and 1,513 went two or three times. The famous numbers come from the 201 men who went four to seven times a week.1
The count runs from 1984 to 2011
The researchers followed every man through national death records
Scroll slowly. Each ember goes out when a man in its group dies.
The totals at the end match the paper.1 It reports only those final counts, so we spread the deaths across the years ourselves.
The records close in 2011
The men who took the most saunas died least often
By 2011, 49% of the once-a-week men had died. It was 38% in the middle group and 31% in the top group.1
Headlines quoted a 40% lower risk of death for the top group. The researchers got that figure after adjusting for age, fitness, smoking, socioeconomic status and other differences between the men.
Rewind to the start
The most frequent bathers started out healthier
They were younger and fitter than the weekly bathers, and 20% of them smoked, against 36% of the weekly men.1 Statistics can only correct for the differences a study measures, and a questionnaire from 1984 left plenty unmeasured.
The paper counts sudden heart deaths
The famous 63% drop in sudden cardiac death comes down to ten men
Ten of the 201 frequent bathers died suddenly of heart problems, against 61 of the 601 weekly bathers. A few deaths either way would move that 63% a long way. On a scale where 1 means no difference, the paper puts the plausible range at 0.18 to 0.75.1
Fitness enters the picture
Fitter men who took fewer saunas did better than less fit men who took more
A 2018 analysis sorted 2,291 of the men by measured fitness as well as by sauna habit. Sudden cardiac death struck 5.5% of the fitter men who took two or fewer saunas a week. The rate was 11.0% for less fit men who took three to seven.2
Once the researchers accounted for fitness, the link with sauna was too weak to rule out chance.
The records run on to 2018
With longer follow-up the difference shrank to 14%
Women join the study in 1998
The link with fewer heart deaths didn't show up in women
In this later sample of 1,688 men and women, the result came from the men. Women who went two or three times a week did no better than women who went once.5
The 73 women in the top group had no heart deaths at all. With no deaths to count, the researchers couldn't estimate their risk.
The study links frequent saunas to fewer deaths in one group of Finnish men
The Finnish men who took the most saunas did die less often, and the link held after the researchers accounted for fitness, smoking, blood pressure and socioeconomic status. It shrank with longer follow-up and disappeared in the fittest men.1,3,6 All of this comes from one group of middle-aged Finnish men. No trial has assigned people to saunas at random and then counted deaths.
Sauna looks like a habit with a plausible upside for the heart. In the same men, measured fitness predicted survival more strongly.6 You'll find the numbers behind the other heart claims on the claims page.
Saunas that reach the study’s 79°C
The Kuopio men sat in traditional hot-rock saunas, and the average session ran 14 minutes at 79°C.1 These two barrels reach that heat.
Where to buy
Nootka Saunas Outdoor Saunas
Nootka 8ft Barrel Sauna
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The studies behind this story
- Finnish men who took the most saunas had fewer deaths over twenty yearsJAMA Internal Medicine, 2015
- Fitness predicted Finnish men's survival more strongly than sauna use didAnnals of Medicine, 2018
- Frequent sauna use went with fewer heart deaths in men and left the question open for womenBMC Medicine, 2018
Sources
- 1.Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine, 2015.
- 2.Combined Effect of Sauna Bathing and Cardiorespiratory Fitness on the Risk of Sudden Cardiac Deaths in Caucasian Men: A Long-term Prospective Cohort Study. Progress in Cardiovascular Diseases, 2018.
- 3.Inflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort study. European Journal of Epidemiology, 2022.
- 4.Frequent sauna bathing offsets the increased risk of death due to low socioeconomic status: A prospective cohort study of middle-aged and older men. Experimental Gerontology, 2022.
- 5.Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC Medicine, 2018.
- 6.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.
This story first ran on our sister site Sauna Hype on Sep 24, 2026.
