Men Who Used A Sauna 4 To 7 Times A Week Had 63% Fewer Sudden Cardiac Deaths

Finland has roughly one sauna for every two people, which makes it the only country on earth where you can study sauna habits the way you would study smoking.

Somebody did, and then followed the men for two decades.

The study

The Kuopio Ischaemic Heart Disease Risk Factor Study took 2,315 middle-aged men, aged 42 to 60, from Eastern Finland, recorded their sauna habits at baseline between 1984 and 1989, and followed them for a median of 20.7 years (Laukkanen et al., JAMA Internal Medicine, 2015).

Over that time: 190 sudden cardiac deaths, 281 fatal coronary heart disease events, 407 fatal cardiovascular events, and 929 deaths from any cause.

The men split into three groups: 601 used a sauna once a week, 1,513 used it two to three times, and 201 used it four to seven times.

What they found

After adjusting for cardiovascular risk factors, compared with once a week:

Sessions per week	Sudden cardiac death
2 to 3	HR 0.78 (95% CI 0.57 to 1.07)
4 to 7	HR 0.37 (95% CI 0.18 to 0.75)

P for trend = 0.005. Similar patterns held for fatal coronary heart disease, fatal cardiovascular disease and all-cause mortality, all with a trend P of 0.005 or better.

Duration mattered separately. Compared with sessions under 11 minutes, sessions over 19 minutes carried a hazard ratio of 0.48 for sudden cardiac death (95% CI 0.31 to 0.75, P for trend 0.002). That held for fatal coronary and cardiovascular events, but not for all-cause mortality, and we mention that because it is the one place the pattern broke.

Does it hold up in women

The 2015 study was men only, which is a real limitation and got repeated far less often than the headline.

A later cohort followed 1,688 people, 51.4% of them women, mean age 63, for a median of 15 years (Laukkanen et al., BMC Medicine, 2018).

Same pattern. After adjustment for established cardiovascular risk factors, physical activity, socioeconomic status and incident coronary heart disease, the hazard ratio for cardiovascular mortality at four to seven sessions a week was 0.23 (95% CI 0.08 to 0.65).

The authors also reported that adding sauna frequency to a conventional risk prediction model measurably improved it.

Now the part that keeps this honest

These are observational cohorts. Nobody randomised anybody to a sauna.

The men who used a sauna four to seven times a week in 1980s Finland were plausibly different from the men who went once, in ways that statistical adjustment can capture only partly. Wealth, health at baseline, social connection, the fact that being well enough to sit in 90 degree heat four times a week is itself a fitness signal.

We have written before about a sauna trial where fitness beat the sauna, and that finding sits directly underneath this one. Heat may be doing real work. Some of what looks like heat is almost certainly the person.

What makes this cohort worth citing anyway is the size of the effect, the dose response, the two-decade follow-up, and the fact that a second cohort including women reproduced it.

Higher frequency and duration of sauna bathing are each strongly, inversely, and independently associated with fatal cardiovascular events in middle-aged to elderly males and females.

Laukkanen et al., BMC Medicine, 2018

Note their word: associated. These authors are careful, and we will be as careful as they are.

What kind of sauna this was

Traditional Finnish sauna. Dry heat, typically 80 to 100 degrees Celsius, wood-fired or electric, usually followed by cooling.

That is not the infrared cabin sold for home use, which runs far cooler and heats differently. Whether infrared produces the same association is a separate question with much weaker evidence, and we have a separate article on it.

What we are and are not saying

Claim	Our line
Sauna prevents heart attacks	Never, not as a THS promise
4 to 7 sessions a week tracked with HR 0.37 for sudden cardiac death	Yes, with the cohort design named
Longer sessions tracked with lower risk too	Yes, and it did not extend to all-cause mortality
This is proof of cause	No. Observational, and fitness is a live confounder
Infrared cabins have the same data behind them	No. These were traditional saunas

Where the design shows up

Heat makes the heart work. Pulse rises, vessels open, blood moves to the skin, and the whole system rehearses something like moderate exercise while you sit still.

That is the interesting part. The body does not seem to have a separate mechanism for heat and for exertion. It has one adaptive response, and several different doors into it.

“A joyful heart is good medicine.” Proverbs 17:22, NASB

The verse carries the conviction. Two thousand three hundred and fifteen men over twenty years carry the number.

What to do this week

If you have access to heat, use it more often rather than longer.

The frequency signal in this data is stronger and more consistent than the duration signal. Four short sessions beat one heroic one, on the numbers as they stand.

And if you have no sauna, this is not a reason to buy one this week. The fundamentals that sit underneath this cohort, movement and fitness among them, are free and have better evidence.

Read this next: the same Finnish cohort, a different outcome, and the one that surprised us more: sauna frequency and dementia. For the trial where something free outperformed the therapy, what a hot bath does, and why fitness beat both.

Sources

1. Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. “Association between sauna bathing and fatal cardiovascular and all-cause mortality events.” JAMA Internal Medicine, 2015;175(4):542-548. https://pubmed.ncbi.nlm.nih.gov/25705824/
2. Laukkanen T, Kunutsor SK, Khan H, Willeit P, Zaccardi F, Laukkanen JA. “Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study.” BMC Medicine, 2018;16(1):219. https://pubmed.ncbi.nlm.nih.gov/30486813/
3. Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JA. “Sauna bathing is inversely associated with dementia and Alzheimer’s disease in middle-aged Finnish men.” Age and Ageing, 2017;46(2):245-249. https://pubmed.ncbi.nlm.nih.gov/27932366/

Article metadata retrieved from PubMed. Photograph from Pexels. Scripture quoted from the New American Standard Bible.

Educational content from True Health Solutions. We do not diagnose or prescribe, and nothing here is a substitute for care from someone who knows your history. The body heals. We write about what supports that design.