Middle-aged to elderly men and women who take frequent sauna baths have a substantially reduced risk of new-onset stroke, according to a 15-year follow-up study published in the journal Neurology.

Stroke is one of the leading causes of disability worldwide, placing a heavy human and economic burden on societies.

The reduced risk associated with sauna bathing was found by a team of scientists from the Universities of Eastern Finland, Bristol, Leicester, Emory, Cambridge and Innsbruck.

“Sauna bathing is a safe activity for most healthy people and even people with stable heart problems,” said study lead author Dr. Setor K. Kunutsor, from the University of Bristol.

“These results are exciting because they suggest that this activity that people use for relaxation and pleasure may also have beneficial effects on your vascular health.”

The findings are based on the population-based Kuopio Ischaemic Heart Disease Risk Factor (KIHD) study and involved 1,628 people with an average age of 63 with no history of stroke.

Based on their frequency of taking traditional Finnish sauna baths (relative humidity 10-20%), the study participants were divided into three groups: those taking a sauna once a week, those taking a sauna two to three times a week, and those taking a sauna four to seven times a week.

The more frequently saunas were taken, the lower was the risk of stroke.

Compared to people taking one sauna session per week, the risk was decreased by 14% among those with two to three sessions and 61% among those with four to seven sessions.

“The findings are very significant and highlight the multiple health benefits of taking frequent sauna baths,” Dr. Kunutsor said.

The association persisted even when taking into account conventional stroke risk factors, such as age, sex, diabetes, body mass index, blood lipids, alcohol consumption, physical activity and socio-economic status. The strength of association was similar in men and women.

“Previous studies have shown that sauna bathing may be associated with a reduced risk of high blood pressure, dementia, and cardiovascular and all-cause mortality, but this is the first study on sauna use and the risk of stroke,” Dr. Kunutsor added.

“Saunas appear to have a blood pressure lowering effect, which may underlie the beneficial effect on stroke risk.”

A limitation of the study was that the study was based on traditional Finnish saunas and the results cannot be applied to other types of heat therapy such as infrared heat exposure, steam rooms and hot tubs.

“Since only a few people in the study never took saunas, we could not compare people who used saunas to people who never used saunas,” Dr. Kunutsor said.

“Evidence suggests some people should not use saunas, including people who recently had a heart attack and those with unstable angina, or chest pain. Elderly people with low blood pressure should use caution when taking a sauna.”

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Setor K. Kunutsor et al. Sauna bathing reduces the risk of stroke in Finnish men and women. A prospective cohort study. Neurology, published online May 2, 2018; doi: 10.1212/WNL.0000000000005606