Europeans have been extolling the health benefits of saunas for centuries, claiming that, beyond promoting relaxation and working up a satisfying sweat, regular sessions inside these specially built high-temperature rooms can do everything from reducing blood pressure to increasing longevity.
Yet similar to other lifestyle studies assessing specific exposures, like those on diet and sleep patterns, investigations into the positive effects of sauna baths have only been able to highlight correlations rather than prove causation.
However, if enough high-quality studies have found associations between forays into dry heat saunas and lowered risk of multiple diseases, then the evidence in favor looks pretty encouraging. At least, that’s the conclusion of a research team, led by Finnish sport scientist Dr Jari Laukkanen, who reviewed the available published literature on traditional dry sauna bathing – characterized by 5- to 20-minute sessions in small rooms, usually wood-lined, heated to 80-100°C (176-212°F), with a humidity of 10 to 20 percent.
“Emerging evidence suggests that beyond its use for pleasure, sauna bathing may be linked to several health benefits, which include reduction in the risk of vascular diseases such as high blood pressure, cardiovascular disease, and neurocognitive diseases; nonvascular conditions such as pulmonary diseases; mortality; as well as amelioration of conditions such as arthritis, headache, and flu,” they wrote in the journal Mayo Clinic Proceedings.
Laukkanen and his colleagues concede that the correlations to some of these protective effects are weaker than others and that well-designed, randomized trials are needed to determine the physiological mechanisms linking sauna sessions to improved bodily functioning. But until we know more, Finns seem to have a reason to rejoice: Saunas are an integral part of their cultural history and residents of the Scandinavian nation continue to take between one and three sessions per week.
Let’s review some of the findings.
According to the analysis, only two studies have prospectively assessed long-term cardiovascular outcomes. One, which followed 2,315 Finnish men for 20.7 years (and was conducted by Laukkanen), found that higher frequency and duration of sauna bathing were associated with lower likelihood of sudden cardiac death, fatal cardiovascular diseases, and all-cause mortality, after adjusting for numerous confounding lifestyle and health factors. The second study, which included 1,628 men and women followed for 15 years, found that taking four to seven sauna sessions/week was associated with a 62 percent less risk of stroke compared with just one sauna session/week.
Laukkanen’s 2,315-man study also revealed that participants who frequently went to saunas had a 66 and 65 percent reduction in risk of dementia and Alzheimer’s, respectively, compared to men who went once a week. Unfortunately, it is impossible to tell if the saunas are really helping protect neurons or if “it is just an enjoyable activity that prevents or delays the development of these memory diseases[.]”
Blood pressure and pulmonary disease
Several investigations suggest that saunas may improve lung function and lower the incidence of respiratory diseases such as asthma, colds, and pneumonia, though these results were gathered from very small cohorts. Studies on vascular health have implied that saunas may improve blood pressure and arterial stiffness, but they either looked solely at short-term effects, were limited by confounders, or used only white male subjects.
Interestingly, the only randomized control trial Laukkanen’s team found proposes that sauna sessions can lessen the intensity of chronic tension-type headaches.
When discussing the supposed health risks of saunas, such as horror stories about sudden heart attacks or severe burns, the authors report that most of the adverse events have occurred when people mix alcohol and saunas – never a good idea.
The short duration extreme heat exposure appears to be safe for most individuals, save those with advanced heart conditions and unstable blood pressure.