February 23rd, 2015
Study Links Sauna Use to Better Health — In Finland
Finnish researchers analyzed data from the Kuopio Ischemic Heart Disease Risk Factor Study. The new analysis focused on 2,315 middle-aged men who had 1, 2-3, or 4-7 sauna bathing sessions per week. After 20 years of followup the rate of sudden cardiac death, fatal coronary heart disease, fatal cardiovascular disease, and all-cause mortality was significantly reduced in people who used the sauna more often.
For instance, when compared to men who had one session a week, the risk of sudden cardiac death was reduced by 22% in men with 2-3 sauna sessions each week and 63% lower in men with 4-7 sauna sessions each week. The overall pattern remained significant after adjusting for baseline differences in cardiovascular risk. In addition, the researchers found that longer sauna sessions were more beneficial than shorter sessions.
Franz Messerli thinks the health benefits of sauna bathing are plausible: “To prevent body over-heating during sauna bathing, cutaneous circulation increases drastically; there is maximal vasodilation. The fall in blood pressure is prevented by an increase in cardiac output mediated mostly by an increase in heart rate and by visceral vasoconstriction. Subsequent cooling in ice water, freezing air, or rolling in snow (as is traditional practice in Finland) causes immediate cutaneous vasoconstriction, which leads to a surge in blood pressure. The effects of both excessive heat and cold are mediated by the sympathetic nervous system. As a consequence, regular use of sauna blunts sympathetic stimulation and cardiovascular responses. The vascular tree is becoming progressively conditioned by rapidly alternating vasoconstriction and vasodilation, which may explain some of the cardiovascular benefits of frequent sauna bathing (and subsequent cooling).”
Some earlier studies have pointed to possible harmful effects of saunas. The researchers found no negative effects from increased sauna usage and speculated that may be due to unique features of Finnish saunas — including the combination of dry heat and high temperatures. They also noted that the benefits observed in the male Finnish population may not be applicable to women or in people not accustomed to regular sauna use. In response to a query, lead author of the study, Jari Laukkanen, said that because only 12 men in the study had no regular sauna use the researchers were unable to explore the comparison of sauna use versus no sauna use. “We investigated the dose of sauna,” he said. In addition, because sauna bathing is a lifetime activity in Finland, the study findings may not apply to people who take up sauna in middle age, for instance. “Further studies are needed to confirm our results in different population settings,” the researchers concluded.
The study “makes me wonder if we should all adopt the intensive sauna strategy — or whether that only works in a country like Finland where saunas are a part of life,” said Harlan Krumholz. “Seriously, it opens a lot of questions about whether such behavioral interventions can exert a positive effect on heart health. The first question for those of us in the U.S. is whether sauna versus no sauna is associated with risk reduction, a question they cannot answer in sauna-prevalent Finland.”
One conclusion seems clear to John Ryan: “Finland just seems like a great place to live,” he said. He also pointed out that in the 1970s Finland had the world’s highest rate of death from cardiovascular disease. This has now been reduced by 65% in men, but the role, if any, of sauna bathing in this major shift is unknown.
In an editor’s note, Rita Redberg would seem to agree with Ryan’s assessment of Finland. She writes that “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.”