Frequent sauna use and blood pressure together predicted long-term mortality risk in Finnish men

A prospective cohort study followed 2,575 middle-aged Finnish men for nearly 28 years to examine whether sauna bathing frequency and systolic blood pressure jointly shaped all-cause mortality risk. Men who bathed in saunas infrequently and had elevated blood pressure faced the highest mortality risk, while frequent sauna users with elevated blood pressure showed a risk that did not reach statistical significance compared with the lowest-risk group.

What the study found

Over a median follow-up of nearly 28 years, 1,618 deaths occurred among the 2,575 participants. After adjusting for other factors, men with elevated systolic blood pressure carried about a 29% higher all-cause mortality risk than those with normal readings, and men who used the sauna infrequently carried about a 16% higher risk than frequent users — both associations were statistically significant.

When the two factors were examined together, men who combined elevated blood pressure with infrequent sauna use faced a 47% higher mortality risk compared with men who had normal blood pressure and used the sauna frequently. By contrast, the group with elevated blood pressure but frequent sauna use showed a hazard ratio of 1.24 that did not cross the threshold of statistical significance, suggesting the elevated-pressure penalty may be attenuated — though this interpretation requires caution.

The authors identified potential additive and multiplicative interactions between blood pressure category and sauna frequency, meaning the combined effect appeared larger than either factor alone would predict. They characterize this as a possible interplay rather than a confirmed mechanism, and the observational design means unmeasured confounders could account for part of the pattern.

The study's conclusions are framed carefully: frequent sauna bathing was associated with a pattern of mortality risk that may partially offset the risk linked to elevated systolic blood pressure, but the authors stop short of claiming a protective causal effect.

Limits worth knowing

The study enrolled only Caucasian men aged 42–61 at baseline from a single Finnish cohort, so findings may not apply to women, other ethnicities, younger adults, or older populations. Sauna habits were self-reported at baseline and not reassessed over the nearly three-decade follow-up, meaning changes in behavior over time were not captured. Blood pressure was measured at a single resting baseline visit, which may not reflect long-term cardiovascular status. The analysis could not fully account for all lifestyle confounders — such as diet, fitness level, or socioeconomic factors — that might independently influence both sauna use and mortality. No funding disclosure is noted in the available abstract.

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