Men who used a sauna at least 2-3 times a week were found to be at lower risk of cardiovascular and all-cause mortality than those who had a once-weekly sauna session.
The research team, including Dr. Jari A. Laukkanen of the University of Eastern Finland in Kuopio, publishes its findings in JAMA Internal Medicine.
Past studies have indicated that sauna bathing has significant benefits for cardiovascular health. Exposure to the high heat of saunas - which is recommended to be around 80-100°C - has been linked to improved blood circulation, reduced blood pressure and better heart function.
Dr. Laukkanen and colleagues note, however, that few studies have investigated the association between long-term sauna use - including the duration and frequency of use - and the risk of sudden cardiac death, fatal coronary heart disease (CHD), fatal cardiovascular disease (CVD) and all-cause mortality.
With this in mind, the researchers assessed such associations among 2,315 men aged 42-60 from eastern Finland who were part of the Finnish Kuopio Ischemic Heart Disease Risk Factor Study.
At study baseline, all men completed a questionnaire disclosing how many times they used a sauna each week, how long each session lasted and the average temperature they bathed at.
Over an average follow-up period of almost 21 years, there were 190 sudden cardiac deaths, 281 cases of fatal CHD, 407 cases of fatal CVD and 929 deaths from all causes.
4-7 weekly sauna sessions linked to lowest risk of cardiovascular, all-cause mortality
The team found that men who engaged in 2-3 sauna bathing sessions each week were 22% less likely to experience sudden cardiac death, 23% less likely to experience fatal CHD and were at 27% lower risk of CVD death and 24% lower risk of all-cause mortality, compared with men who used a sauna once a week.
Men who had 4-7 sauna sessions benefited even more; they were at 63% lower risk of sudden cardiac death, 48% lower risk of CHD death, 50% lower risk of CVD death and were 40% less likely to die from all causes, compared with those who had one sauna session a week.
In addition, the researchers found that the duration of sauna sessions appeared to influence results. They found that, compared with men who spent less than 11 minutes in a sauna, those who spent 11-19 minutes in a sauna were 7% less likely to experience sudden cardiac death, while men who spent more than 19 minutes in a sauna were at 52% lower risk.
Longer sauna duration was also associated with lower risk of fatal CHD and fatal CVD, though it did not appear to affect the risk of all-cause mortality.
The researchers say their findings remained even after accounting for men's smoking status, blood pressure, cholesterol levels, triglyceride levels and other factors that may have influenced the results.
Commenting on their findings, the authors say:
"This study provides prospective evidence that sauna bathing is a protective factor against the risk of sudden cardiac death, fatal CHD, fatal CVD and all-cause mortality events in the general male population.
Our results suggest that sauna bathing is a recommendable health habit, although further studies are needed to confirm our results in different population settings."
The researchers add that since their study was conducted in males, further research is needed to see if similar results can be found in females. In addition, they say future studies should look at whether the results can be replicated in populations who are not accustomed to sauna use.
Though the team did not investigate why frequent sauna use appeared to protect against cardiovascular and all-cause mortality, they point to previous research that suggests sauna bathing can increase heart rate in a similar way to low- and moderate-intensity exercise, which is known to have heart benefits.
Medical News Today recently reported on a study published in the Journal of the American Heart Association claiming that every minute of activity can boost heart health for older adults with limited mobility.