Key Takeaway
Finnish men using sauna 4-7 times per week had 40% lower all-cause mortality and 50% lower cardiovascular mortality compared to once-weekly users over 20 years.
Summary
This landmark 20-year prospective study followed 2,315 Finnish men and examined the relationship between sauna bathing frequency and mortality outcomes. It remains one of the most cited studies in the sauna literature.
The key finding was a strong dose-response relationship: men who used the sauna 4-7 times per week had dramatically lower mortality than those using it once weekly. All-cause mortality was 40% lower, cardiovascular mortality 50% lower, and sudden cardiac death 63% lower.
While observational (cannot prove causation), the study's large size, long follow-up, and dose-response relationship provide strong evidence for sauna's health benefits.
Methods
- 2,315 middle-aged Finnish men followed for 20.7 years (median)
- Sauna habits assessed at baseline via questionnaire
- Categories: 1x/week, 2-3x/week, 4-7x/week
- Primary outcomes: cardiovascular death, sudden cardiac death, all-cause mortality
Key Results
- 4-7x/week vs 1x/week comparisons:
- All-cause mortality: 40% lower (HR 0.60)
- Fatal CVD: 50% lower (HR 0.50)
- Sudden cardiac death: 63% lower (HR 0.37)
- Dose-response relationship observed
Limitations
- Observational study (cannot prove causation)
- Only Finnish men studied
- Healthy user bias possible (healthier people may sauna more)
- Self-reported sauna habits at baseline only