Sauna and heart health: what a 20-year study found
A Finnish study linked more frequent sauna use with fewer fatal heart events. What can, and can’t, we take from it?
The short version
Researchers followed 2,315 middle-aged men in eastern Finland for a median of 20.7 years. Men who reported more frequent sauna use had lower rates of fatal heart events during follow-up than men who went once a week. For sudden cardiac death, the difference was large in relative terms. But the men chose their own sauna habits, and those habits were asked about only once. The study shows an association in one group of Finnish men, not proof that sauna caused the difference.
Keep in mind
An association, not proof of cause and effect. The study included only men, and they chose their own sauna habits.
What they found
Men who reported more frequent sauna use had lower rates of fatal heart disease, and of death from any cause, during follow-up. The more often the men used the sauna, the lower the rates tended to be.
For sudden cardiac death, men who reported four to seven sessions a week had a hazard ratio of 0.37 (95% confidence interval 0.18 to 0.75) compared with men who reported one session a week. Put simply, their observed rate was about 63% lower than in the once-a-week group. That is a relative difference within this group of men, not a drop of 63 percentage points, and not a prediction for any one person.
The wide confidence interval is a reminder of how uncertain that estimate is.
What this means for your practice
If you enjoy the sauna, this is an interesting part of the story. It does not tell you how often or how long to go: the frequencies above are groups the researchers compared, not advice.
This does not establish a sauna routine to follow, or show that a KUUME ritual has these effects.
Methods and limitations
What the researchers did
The researchers asked 2,315 middle-aged men in eastern Finland how often they used a sauna. The men were part of a long-running health study, the Kuopio Ischaemic Heart Disease (KIHD) study. Deaths were then followed through national registers for a median of 20.7 years.
This is an observational study: nobody was asked to change their habits. The researchers compared men with different sauna habits, for example men who reported four to seven sessions a week with men who reported one.
The analysis took into account other factors that could explain a link, such as age, blood pressure, cholesterol, smoking, alcohol and physical activity.
How much can this tell us?
The study has real strengths: a large group, a very long follow-up and deaths taken from official registers.
But it is observational. Men who used the sauna often may have differed in other ways, such as their health or how active they were, that the statistics could not fully capture. Sauna habits were asked about once, at the start, and only men from one region of Finland took part.
Other analyses of the same group of men, such as the study of sauna and dementia, share this data. Together they are one source of evidence, not several independent ones.
What makes it useful
- 2,315 men followed for a median of 20.7 years
- Deaths taken from national registers
- Other risk factors taken into account
What limits it
- Observational: an association, not proof of cause
- Only men, from one region of Finland
- Sauna habits asked about once, at the start
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular sauna means fewer deaths from heart disease. Some support
Low certaintyLarge effectIllness and death
Sudden cardiac death 63% fewer
Likely 25% to 82%
Fewer cases than the comparison group. The bar is the best estimate, the band behind it the likely range.
Regular sauna helps you live longer. Some support
Low certaintySmall effectIllness and death
From the same participant group as 7 other articles in The Study, so we count them as one group of people.
Read the original
Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Intern Med. 2015;175(4):542-548.
DOI 10.1001/jamainternmed.2014.8187 · PubMed 25705824