Frequent sauna use and high fitness levels linked to reduced risk of psychosis, study finds

A recent study published in the Journal of Psychiatric Research sheds light on the potential mental health benefits of frequent sauna bathing and high cardiorespiratory fitness. The research suggests that regular sauna sessions, especially when combined with good fitness levels, can reduce the risk of developing psychosis.

Psychotic disorders are severe mental health conditions characterized by disruptions in thinking, perception, and behavior. Individuals with these disorders often experience hallucinations, such as hearing or seeing things that aren’t there, and delusions, which are strong beliefs that are not based in reality. These symptoms can lead to significant distress and impair daily functioning, affecting one’s ability to maintain relationships, work, and perform everyday activities. Common examples of psychotic disorders include schizophrenia and schizoaffective disorder.

“Mental disorders such as psychosis are major public health burdens, but they are also preventable conditions. Hence, the need to explore modifiable factors than can be manipulated to mitigate the risk of these mental health disorders,” said study author Setor Kunutsor, an associate professor in epidemiology at the University of Leicester.

“We have previously shown that having frequent sauna baths can reduce the risk of mental health disorders such as psychosis. We have also shown that high cardiorespiratory fitness (CRF) levels, which are largely determined by regular physical activity, can also reduce the risk of psychotic disorders. Research has shown that there is a synergistic interplay between sauna bathing and cardiorespiratory fitness.”

“In fact, we have shown that the combination of frequent sauna bathing sessions and higher CRF levels confer stronger protection against some adverse health outcomes compared with each modality alone. Hence, we decided to investigate if this applies to psychosis.”

The researchers conducted their study by analyzing data from the Kuopio Ischemic Heart Disease (KIHD) cohort, a prospective population-based study based in Finland. The cohort included 2,682 middle-aged and older men aged between 42 and 61 years at the time of recruitment, with baseline assessments carried out between March 1984 and December 1989. These assessments included detailed evaluations of participants’ sauna bathing habits, cardiorespiratory fitness levels, and other health and lifestyle factors.

To determine the frequency of sauna bathing, participants completed self-administered questionnaires that asked about their weekly sauna use. Based on their responses, participants were categorized into two groups: those who used the sauna two or fewer times per week (low frequency) and those who used it three to seven times per week (high frequency).

Cardiorespiratory fitness, a measure of the body’s ability to supply oxygen to muscles during sustained physical activity, was assessed through peak oxygen uptake during a maximal exercise tolerance test. This test involved participants exercising on a cycle ergometer while their respiratory gases were analyzed to measure their peak oxygen uptake.

The researchers followed the participants for a median duration of 25 years, tracking the incidence of psychotic disorders through computerized linkage to the National Hospital Discharge Register.

The study found that frequent sauna bathing was associated with a significantly reduced risk of psychosis. Men who engaged in high-frequency sauna use (three to seven times per week) had a markedly lower risk of developing psychotic disorders compared to those with low-frequency sauna use (two or fewer times per week). Specifically, the hazard ratio (HR) for psychosis among men with high-frequency sauna use was 0.49, indicating a 51% reduction in risk compared to those with low-frequency sauna use.

“Having frequent baths and high fitness levels (determined by regular physical activity) can each reduce the risk of mental health conditions such as psychosis,” Kunutsor told PsyPost. “It appears having frequent sauna baths might have more beneficial impact on mental health conditions than having high fitness levels.”

When examining the combined effects of sauna use and cardiorespiratory fitness, the researchers found that men with both high-frequency sauna use and medium-to-high fitness levels had the lowest risk of psychosis. The multivariable-adjusted hazard ratios for psychosis were significantly lower for men with high sauna use and either medium or high fitness levels compared to those with low sauna use and low fitness levels.

Men with high sauna use and low fitness levels still experienced a substantial reduction in risk, with a hazard ratio of 0.26, indicating a 74% lower risk of psychosis. The findings suggest that while both frequent sauna use and higher fitness levels independently contribute to a reduced risk of psychosis, sauna use may have a particularly strong protective effect.

Kunutsor was surprised by “the fact that having frequent sauna baths (3-7 sauna sessions/week) might have more beneficial impact on mental health conditions than having high fitness levels. Given the substantial and well known health benefits associated with regular physical activity and high fitness levels, we expected high fitness levels to have more impact.”

The researchers statistically controlled for various potential confounding factors such as age, cholesterol levels, smoking status, diabetes, heart disease, education, alcohol consumption, total energy intake, socioeconomic status, physical activity, and markers of inflammation. But the study, like all research, includes some caveats.

The study is observational, meaning it can identify associations but cannot establish cause and effect. This limits the ability to definitively conclude that sauna use and fitness directly reduce the risk of psychosis. Additionally, the study focused solely on middle-aged and older men, making it difficult to generalize the findings to women, younger individuals, or other populations.

“The current findings add to the growing evidence base on the health benefits of sauna and that sauna use may have protective effects on mental health,” Kunutsor said. “Given that the current findings are based on an observational study, interventional studies in the form of randomized controlled trials are needed to confirm these findings. We also want to explore the physiological and psychological mechanisms through which sauna bathing impacts mental health.”

The study, “Frequent sauna bathing and psychosis: Interrelationship with cardiorespiratory fitness,” was authored by Setor K. Kunutsor, Jussi Kauhanen, and Jari A. Laukkanen.