This week we wanted to share some of the emergent science behind heat exposure and sweating during sauna use. While saunas can be highly relaxing, aid in soothing aches and pains, and be a great mindfulness activity, science is also finding possible clinical benefits from habitual use, something many global cultures have subjectively observed for thousands of years.
For whatever reason, Americans typically ignore their gym’s sauna or sparingly go, something that may be costing us in terms of our health and longevity. One classically pro-sauna country, Finland, has seemingly led the charge in heat exposure research as it has emerged in prominence over the last decade.
While it’s important to note that correlation does not necessarily equal causation in medical studies, high volume, diverse sample sizes, long-range longitudinal studies, and control groups are seen as the gold standard for research to buffer against such concerns. The University of Eastern Finland seemingly had this in mind when organizing a study tracking over 2,300 men aged 42-60 over the course of 20 years. This sample size, continuity across years, and diversity of age can be rare in medical studies, something that makes its findings all the more compelling.
Participants were studied categorically by those who elected to sauna once a week, those who went two to three times per week, and participants who went four to seven sessions a week. Average sauna session times were a median of 14 minutes across all studied groups, though longer durations were thought to be more beneficial. Researchers revealed several shocking findings of their study in 2015 in a publication within JAMA Internal Medicine Journal:
Significant cardiovascular disease, event, and mortality reduction
- Compared to men who reported one sauna session per week, the risk of sudden cardiac death (SCD) incidence was 22 percent lower for men who did 2-3 sauna sessions per week and a whopping 63 percent lower for those who did 4-7 sessions per week.
- Fatal coronary heart disease (CHD) events in men were 23 percent lower for 2 to 3 sauna sessions per week and 48 percent lower for 4 to 7 sessions compared to those who did just one session.
- Fatal cardiovascular disease (CVD) deaths were also 27 percent lower for men who took saunas 2 to 3 times a week and 50 percent lower for men who were in a sauna 4 to 7 times as compared to men who went just went once.
- Compared with men who spent less than 11 minutes in the sauna, the risk of SCD was 7 percent lower for sauna sessions of 11 to 19 minutes and 52 percent less for sessions lasting more than 19 minutes. Similar associations were seen for fatal CHDs and fatal CVDs but not for all-cause mortality events.
Researchers controlled for heart disease and other issues in the study sample, and followed subjects over a 20-year period. The Finnish study revealed regular sauna use may be a tool to improve cardiovascular health due to its ability to induce increased heart rates and blood vessel dilation, both things which enhance blood circulation. Saunas induce a temporary heat stress that gets the heart pumping, a key feature in any normal cardiovascular exercise.
Significant reductions in dementia, Alzheimer’s disease
Another compelling 2017 study published in the Journal Age and Aging by Finland’s Foundation for Cardiovascular Research studied a cohort of 2,300 men across a timeframe of around 25-30 years from baseline examination to final follow-up. Statistical analysis by researchers controlled for potentially confounding factors such as age, alcohol use, BMI, blood pressure, smoking, diabetes, heart disease, physical activity, and socioeconomic status. These factors strengthen their dementia and Alzheimer’s Disease findings by reducing possible alternative explanations.
It’s also notable that FCR’s study was initiated to measure heart health with habitual sauna use, not cognitive decline, and researchers only made discoveries in dementia and Alzheimer’s Disease incidence as a result of open data within Finland’s healthcare system. Although they were not looking for it initially, their findings demonstrated that:
- Compared to men who went to the sauna once per week or less, men who attended sauna 2-3 times per week were 22% less likely to develop dementia and 20% less likely to develop Alzheimer’s disease.
- Men who frequented the sauna 4-7 times a week were 66% less likely to develop dementia and 65% less likely to develop Alzheimer’s disease.
The additive benefit of exercise as a guard against cognitive decline has long been demonstrated within scientific literature, so it’s not shocking that sauna usage may follow this trend. What makes sauna unique is its ability to provide cardiovascular benefits to those who are otherwise unable to exercise due to injury, medical conditions, or advanced age.
Researchers theorized that lessened levels of full-body inflammation, lower blood pressure, engagement in leisure activity, and a sense of community (all possible benefits of sauna) were potentially causative within the context of their dementia findings. Research is ongoing, however, to the mechanisms of sauna and various biological responses within the body such as heat shock protein production.
All-cause mortality and emerging research avenues
The 2015 Finnish sauna study we previously mentioned also published another shocking data point. It found that a 40% all-cause mortality reduction existed within groups who went to sauna most frequently. This finding comes with a heavy asterisk of genetic, dietary, and population-based health explanations, however, and it’s noteworthy that it only studied men, not women. It’s possible, for instance, that frequent sauna usage combined with a traditional Finnish lifestyle and diet brings about these outcomes but an American lifestyle and diet combined with sauna do not. It’s also possible these benefits are not as pronounced or present within women. That said, not all studies are based in Finland or just on men, and evidence of a myriad of other health benefits only continue to trickle in.
Reductions in risk profiles for stroke, respiratory disease, venous thromboembolism, pneumonia, psychotic disorders, depression, anxiety, neuropathic and rheumatic disease, arterial stiffness, pulmonary function issues, hypertension, circulation issues, stress and cortisol levels, inflammation, and risk of death from general socioeconomic conditions have all been observed anecdotally or directly within studies of habitual sauna use. Positive effects of sauna use post-workout on athlete endurance, white blood cell count, cortisol levels, and routine illness incidence are also actively being studied. To say that heat stress is an emergent scientific field within the context of protective health, longevity, and healthful aging is an understatement.
If you’d like to learn more, Mayo Clinic’s aggregated breakdown of clinical research is a great place to start, and we encourage you to check out the links below to learn more! Happy sweating!
Studies and sources:
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2130724
https://academic.oup.com/ageing/article/46/2/245/2654230
https://www.mayoclinicproceedings.org/article/S0025-6196(23)00008-3/fulltext
*This blog is conversational in nature and does not constitute medical advice. It does not suggest any medical interventions, lifestyle changes, or health interventions of any kind be made by the reader without the express recommendation and discussion with a licensed medical doctor. Fountain Mortgage, the author, and the Shawnee Mission Post are not advocating any action be taken by the reader, and any content and discussion is solely for the education and enjoyment of the reader. Please consider your individual health, risk profile, and medical provider’s advice before undertaking any lifestyle changes.
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