Finnish sauna bathing is a wonderful way to pursue relaxation, wellness, and personal pleasure. It is a tradition in Finland. Now, new evidence is emerging that suggests sauna bathing may offer some significant health benefits. This evidence suggests that regular sauna bathing may alleviate and reduce the risk of acute and chronic disease conditions.
During the last 10 years, plenty of research across different countries points to the health benefits of a sauna in addition to how the benefits are derived. Still, some evidence is mixed and some researchers are calling for aggregation of data for better interpretation.
Sauna bathing
Sauna bathing is a form of passive heat therapy that exposes you to high temperatures for a short period. The typical Finnish sauna has dry air and a high temperature, although the humidity can be increased by adding water onto the hot rocks of the sauna heater. Temperatures are usually set between 80°C to 100°C. A typical sauna bath will be a short period in the heat interspersed with cooling-off periods such as a shower, swimming in a pool, or simply resting in an environment with a lower air temperature. The duration of the sauna is usually between 5 to 20 minutes depending on an individual’s comfort levels. Finnish sauna bathing habits may have changed over time, but still, a typical Finnish person has a sauna bath at least once per week, with the average habitual frequency being 2 to 3 times per week.
While enjoying the sauna, your heart rate may increase from baseline up to 120 to 150 beats per minute. This is despite no physical activity. A part of blood volume is diverted from the internal organs to the body’s peripheral parts with decreasing venous return. This is most likely a response to heat stress.
Sauna and vascular outcomes
Hypertension
Evidence from several studies suggests sauna bathing has a positive effect on blood pressure modulation. However, these studies were done with participants who had preexisting vascular disease, and the studies examined only the short-term effects of sauna exposure.
Two recent studies by Lee et al and Laukkanen et al looked at 100 adults aged 32-75 years with at least 1 cardiovascular risk factor. They reported reductions in systolic and diastolic blood pressure after a 30-minute sauna session. Saunas have been shown to help arterial stiffness. And, another group of researchers found that both exercise and sauna were important non-pharmacological strategies to lower blood pressure.
Still, more research needs to be conducted on the long-term effects of regular saunas on blood pressure. In the only long-term study, researchers found that the participants who took 4 to 7 saunas per week had a 47% reduced risk of developing hypertension. These participants were followed for close to 25 years. Regular sauna bathing may prove to be beneficial in the reduction of high blood pressure, although more studies should be conducted to affirm these findings.
Cardiovascular disease
Scientists point out that those who have regular sauna use may also have lifelong healthy habits in comparison to participants in studies that examine physical exercise. In addition, only 2 reports have looked at regular sauna use on the long-term risk of cardiovascular disease. Laukkanen et al in their prospective cohort study of 2315 Finnish men followed for 20.7 years showed that higher frequency and duration of sauna bathing were inversely and independently associated with risk of sudden cardiac death (SCD), fatal coronary heart disease, and CVD, and all-cause mortality. The study looked at a wide range of variables such as weight, systolic BP, serum low-density lipoprotein cholesterol level, smoking, alcohol consumption, previous myocardial infarction, type 2 diabetes mellitus, CRF level, resting heart rate, physical activity, and socioeconomic status.
Neurocognitive disease
Neurocognitive disease has many causative factors like impaired cardiovascular function, inflammation, hypertension, and oxidative stress. New evidence points to the protective effects that saunas may have on neurocognitive disease.
In a population-based prospective cohort study conducted with 2315 Finnish men aged 42 to 60 years at baseline, men who had 4 to 7 sauna sessions/wk compared with those who had 1 sauna session/wk had a 66% and 65% reduced risk of dementia and Alzheimer disease, respectively.
Whether sauna exposure gives its neurocognitive protective effects by mediation in the pathways contributing to these diseases, or it is just an enjoyable activity that prevents or delays the development of these memory diseases is not clearly understood. More research is necessary, but the current evidence seems very promising.
Sauna bathing and nonvascular diseases
Pulmonary disease
Regular use of a sauna may also have positive effects on some nonvascular conditions. Some studies show that sauna use improves lung capacity by improving vital capacity and volume, ventilation, and forced expiratory volume. Another study reviewed previous research and found that sauna use improved breathing in patients with asthma or chronic bronchitis.
Ernst et al looked at 25 volunteers who were exposed to the sauna and 25 controls. Those who used the sauna had half the incidence of common colds versus the control group.
In the first prospective evaluation of the long-term effect of sauna bathing on the risk of pulmonary disease, Kunutsor et al found moderate (2-3 sessions/wk) to high (4-7 sessions/wk) frequency sauna bathing was linked with a reduced risk of respiratory diseases like chronic obstructive pulmonary disease, asthma, or pneumonia. In a separate analysis limited to pneumonia cases, having regular sauna baths was also associated with a reduced risk of pneumonia.
Sauna bathing and other health benefits
Research has also linked sauna use to improvement in pain and symptoms associated with musculoskeletal disorders such as osteoarthritis, rheumatoid arthritis, and fibromyalgia.
Some evidence suggests that sauna use may be beneficial for patients with psoriasis. And considerable evidence exists that regular sauna use is associated with better overall well-being, physical function, vitality, and social function.
Your body’s pathways for health benefits of sauna use
The research points to several mechanistic pathways the underlie the effects of sauna use on vascular and nonvascular disease. These pathways have effects that include reduction in systemic BP; improvement in endothelial function; reduction in oxidative stress and inflammation; beneficial modulation of the autonomic nervous system; positive alteration in levels of circulating vascular risk factors such as natriuretic peptides and lipids; hormonal changes; improved arterial stiffness, arterial compliance, and intima-media thickness; and improvement in the cardiorespiratory system as well as cardiovascular function. Indeed, these pathways are involved in the pathophysiology of chronic disease outcomes such as type 2 diabetes, CVD, and mortality.
A typical hot and dry Finnish sauna increases body temperature, which causes more efficient skin blood flow, leading to increased cardiac output, whereas blood flow to internal organs decreases. Increased sweating is accompanied by a reduction in blood pressure and a higher heart rate, while cardiac stroke volume is maintained. Sauna use stimulates hormonal changes, which include increases in levels of plasma renin, cortisol, and growth hormone. There is stimulation of the sympathetic nervous system due to the high temperature, which increases the production of norepinephrine. Increases in levels of norepinephrine-induced by sauna exposure have been reported to be similar to those induced by maximal physical activity. Sauna therapy may also exert its effects via the changes in levels of blood-based cardiovascular biomarkers such as markers of glucose metabolism and insulin resistance, natriuretic peptides, and cardiac troponin T, and inflammatory markers such as interleukins and C-reactive protein.
Finnish sauna baths are linked with a decrease in circulating levels of inflammatory markers such as high-sensitivity C-reactive protein, fibrinogen, and leukocytes at baseline and long-term follow-up. Finnish sauna baths have also been found to positively modulate circulating levels of lipids such as total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. There is also evidence that sauna exposure could boost the immune system, which may partly explain why sauna baths reduce susceptibility to common colds and prevent infections in healthy individuals. Furthermore, the effects of sauna bathing on vascular and nonvascular diseases may in part be mediated via reduced oxidative stress, as oxidative processes are known to be involved in the etiology of several disease conditions. However, some of the results have been conflicting.
In addition to other potential pathways that might be involved, the effect of sauna on psychotic symptoms might be via an ability to promote mental health and well-being. The beneficial effect of sauna bathing on pulmonary conditions might be due to its direct effects on the airways and lung tissue, which include improvement in ventilation and lung function and reduction in pulmonary congestion. The pain-relieving pathways of sauna exposure in musculoskeletal conditions may be mediated via the sensory nerve endings in the skin. It has been reported that heat stress interspersed with intense cooling-off periods promotes the analgesic effects, as reflected by the increased circulating levels of β-endorphins. The feelings of relaxation and well-being associated with sauna sessions might be linked to the increased production of circulating levels of hormones such as endorphins.
Final thoughts
While all of this research is exciting, you do need to remember that there are established guidelines for the prevention and management of the acute and chronic disease conditions discussed above. Talk to your own doctor about your specific circumstances.
Therefore, more research is necessary to recommend sauna bathing as a routine remedy for the treatment or prevention of these conditions. Well-designed studies with long-term follow-up are needed for robust evidence and stronger proof of the health benefits of frequent sauna usage. Plus, the evidence is based on Finnish sauna baths with temperature settings around 80°C. It is not known whether saunas operating at lower temperatures or other passive heat therapies would yield similar cardiovascular effects and health benefits.
Overall, the data is a bit mixed mostly due to uncontrolled, small studies from several decades ago and observational study designs with limiting biases. Although there is a possibility that factors such as physical activity and preexisting disease could explain some of the findings in some of these observational designs, it is unlikely as most of these studies took into account these factors in their analyses and conducted sensitivity analyses to minimize the influence of these biases.
More recent research suggests that a combination of regular physical activity and saunas result in a considerable reduction in risk of fatal cardiovascular and all-cause mortality events compared with each modality alone. The findings indicate that physical activity and sauna bathing each have independent effects on vascular disease, suggesting the likelihood that the recent finding on the beneficial effects of sauna bathing on CVD is not due to physical activity or exercise.
So, despite limitations in previous studies, the evidence does show clinical improvements. In the future, doctors may be recommending saunas for people with cardiovascular risk factors and stable cardiac patients as a pleasant therapeutic.
Still, further research is necessary. In the meantime, start a sauna routine slowly, check your individual tolerance, and prudently increase the intensity and frequency.
In general, sauna bathing is a well-tolerated activity, simple to use, and enjoyable; does not involve physical exertion, and has a good safety profile.