Research found that middle-aged men who take frequent saunas are significantly less likely to die from conditions such as heart disease than those who do not.
Those who visited saunas most often - up to once every day - experienced the greatest health benefit. As even compared with men who took one sauna a week, their risk of dying from cardiovascular disease was 50% lower.
Longer time spent sweating it out in each sauna session also appeared to be protective.
The study was conducted among 2,315 men aged 42 to 60 from eastern Finland, where there is a strong sauna tradition.
Researchers followed their progress for around 21 years comparing death rates between those who went to the sauna once a week and others who made more frequent visits.
During the follow-up period they recorded 190 sudden cardiac deaths, 281 fatal cases of coronary heart disease, 407 deaths from cardiovascular disease and 929 deaths from "all causes".
The risk of sudden cardiac death was found to be 22% lower for men who had two to three sauna sessions per week and 63% lower for those visiting a sauna four to seven times a week.
A similar pattern was seen for coronary heart disease, with two to three sessions reducing the risk of death by 23% and four to seven sessions by 48%.
Cardiovascular disease death rates were cut by 27% when men made two to three visits and by 50% when they made four to seven.
For all-cause mortality, a sauna two to three times a week was associated with a 24% lower risk of death and four to seven visits with a reduction of 40%.
Participants benefited more the longer they spent in the sauna. Compared with men staying hot for less than 11 minutes, those whose sessions lasted 11 to 19 minutes were 7% less likely to suffer a sudden cardiac death while more than 19 minutes was associated with a 52% reduced risk.
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A similar pattern was seen for fatal coronary heart disease and cardiovascular disease, but not for all-cause mortality.
Why saunas might have this effect remains unknown. The scientists wrote: "Further studies are warranted to establish the potential mechanism that links sauna bathing and cardiovascular health."
Dr Rita Redberg, from the University of California at San Francisco, who is the journal's editor-in-chief, noted: "Although we do not know why the men who took saunas more frequently had greater longevity (whether it is the time spent in the hot room, the relaxation time, the leisure of a life that allows for more relaxation time, or the camaraderie of the sauna), clearly time spent in the sauna is time well spent."