Frequent sauna use is associated with lower inflammatory markers over 11 years.
Frequent sauna use is associated with lower levels of several inflammatory markers over time. Researchers examined sauna habits in 2,269 middle-aged Finnish men and measured high-sensitivity C-reactive protein (hsCRP), fibrinogen, leukocyte count, and gamma-glutamyltransferase at baseline and again approximately 11 years later.
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Compared with men who reported one sauna session per week, those reporting four to seven weekly sessions had, on average:
- 1.66 milligrams per liter lower hsCRP, a marker of systemic inflammation.
- 0.16 grams per liter lower fibrinogen, a clotting protein that also rises during inflammation.
- 0.49 billion fewer leukocytes per liter of blood at follow-up.
Sauna frequency was not significantly associated with gamma-glutamyltransferase, the study's proxy for oxidative stress.
These findings describe resting biomarkers rather than the temporary immune-cell mobilization that occurs immediately after a sauna session. The two patterns are not necessarily contradictory: an acute stressor can briefly raise circulating immune cells while repeated exposure is associated with a lower-inflammatory resting state. However, this was an observational cohort study. It cannot establish that sauna caused the biomarker differences or rule out residual differences between frequent and infrequent users.