What Does the Research Say About Sauna Bathing?

Regular sauna bathing is linked to a lower risk of heart disease and death in long-running Finnish studies, with the strongest associations in men who used a sauna four to seven times a week. The evidence is promising but mostly observational and largely from one population, so it shows that frequent sauna users live longer, not yet that the sauna is why.

This article is general information, not medical advice. If you have heart disease, low or uncontrolled high blood pressure, or are pregnant, ask your doctor before using a sauna.

The Finnish Studies

The best-known evidence comes from the Kuopio Ischaemic Heart Disease Risk Factor Study in eastern Finland, where most homes have a sauna. Laukkanen and colleagues followed 2,315 men aged 42 to 60 for a median of 20.7 years:

• Compared with one session a week, four to seven sessions a week was associated with a 63% lower risk of sudden cardiac death and a 40% lower risk of death from any cause, after adjusting for cardiovascular risk factors.
• Two to three sessions a week was associated with smaller reductions.
• Sessions longer than 19 minutes were associated with a lower risk of sudden cardiac death than sessions under 11 minutes, though not with lower all-cause mortality.

The sauna in these studies was a traditional Finnish one: dry heat at about 80 °C to 100 °C, with water thrown on the stones for bursts of humidity.

Why Caution About Cause

Frequent sauna users may differ from others in ways the adjustments don’t capture: more leisure time, better health to begin with, and social habits. Most of the data come from middle-aged Finnish men. In a 2018 review of the evidence, Laukkanen, Laukkanen, and Kunutsor described the associations and plausible mechanisms, and called for trials to confirm them.

What a Session Does

A hot sauna raises skin temperature to about 40 °C and heart rate to levels like moderate exercise, then blood vessels widen and blood pressure tends to fall afterwards. The 2018 review summarised short-term effects, including lower blood pressure and improved function of the blood vessels’ lining, which could explain part of the link with heart disease.

Using a Sauna Safely

• No alcohol before or during, which raises the risk of low blood pressure, arrhythmia, and fainting.
• Drink water before and after to replace sweat.
• Leave if you feel unwell, dizzy, or nauseous, and stand up slowly.
• Start shorter, at 5 to 10 minutes, if you’re new to it.

Following It in Kaizora

Log a sauna as an activity on Activities, and Kaizora adds its duration to Sauna Time and counts it in Sauna Sessions, both summed, so a week’s value is its total. A habit such as “at least 4 sauna sessions in 7 days” follows the frequency the studies looked at; see Habits. On Correlations, sauna time beside Systolic Blood Pressure or Total Sleep Time shows whether they move together for you.

The Short Version

• Finnish men using a sauna four to seven times a week had lower risks of heart disease and death.
• The evidence is observational and mostly from one population.
• Avoid alcohol, drink water, and leave if you feel unwell.

Sources

• Laukkanen T et al., “Association between sauna bathing and fatal cardiovascular and all-cause mortality events,” JAMA Internal Medicine 175, no. 4 (2015): 542. doi:10.1001/jamainternmed.2014.8187
• Laukkanen JA, Laukkanen T, Kunutsor SK, “Cardiovascular and other health benefits of sauna bathing: a review of the evidence,” Mayo Clinic Proceedings 93, no. 8 (2018): 1111–1121. doi:10.1016/j.mayocp.2018.04.008