Sauna Bathing and Risk of Psychotic Disorders: A Prospective Cohort Study

Abstract

Objective: Sauna bathing has been suggested to promote mental well-being and relaxation, but the evidence is uncertain with respect to mental disorders. We aimed to assess the association of frequency of sauna bathing with risk of psychosis in the Kuopio Ischemic Heart Disease prospective population-based study. Subjects and Methods: Baseline sauna bathing habits were assessed in 2,138 men aged 42–61 years who had no history of psychotic disorders. Participants were classified into three groups based on the frequency of sauna bathing (once, 2–3, and 4–7 times per week). Results: During a median follow-up of 24.9 years, 203 psychotic disorders were recorded. A total of 537, 1,417, and 184 participants reported having a sauna bath once a week, 2–3 times, and 4–7 times per week, respectively. In Cox regression analysis adjusted for age, compared to men who had 1 sauna session per week, the hazard ratio (95% confidence intervals) of psychosis for 4–7 sauna sessions per week was 0.23 (0.09–0.58). In a multivariable model adjusted for several risk factors and other potential confounders, the corresponding hazard ratio was 0.21 (0.08–0.52). The association was similar after further adjustment for total energy intake, socioeconomic status, physical activity, and C-reactive protein (0.22 [0.09–0.54]) and was unchanged on additional adjustment for duration of a sauna session and temperature of the sauna bath (0.23 [0.09–0.57]). Conclusion: Our study suggests a strong inverse and independent association between frequent sauna bathing and the future risk of psychotic disorders in a general male population.

Longitudinal association between CRP levels and risk of psychosis: a meta-analysis of population-based cohort studies

“…Of the two, we included the study with the longer follow-up 34 . Consequently, four studies were included in meta-analysis 28 , 30 , 31 , 34 . Please see Supplementary Fig.…”

“…The studies had an average follow-up length of 14.55 years (SD = 7.58) for psychosis after CRP assessment at baseline. Two studies involved relatively young adults with psychosis from specific birth cohorts (mean age at outcome assessment around 24–26 years) 31 , 34 , while two involved older adults (mean age at the outcome of 64–78 years) 28 , 30 . Samples were, on average, 60.2% male (range: 44.5–100%).…”

“…However, there are important issues that need to be considered to allow more definitive conclusions. For example, there is heterogeneity in sample age with some studies conducted in relatively young 29 , 31 – 34 and some in relatively older populations 28 , 30 . While these studies have controlled for various confounders, variables included varied from study to study.…”

“…While these studies have controlled for various confounders, variables included varied from study to study. Third, not all studies excluded participants with suspected infection, as measured by a fixed CRP threshold 28 , 30 , 33 . Therefore, a more streamlined analysis across cohorts with consistent adjustment for key confounders is required.…”

Harnessing the Four Elements for Mental Health

“…In respect to specific effects on mental health outcomes from sauna, there is overwhelming anecdotal evidence from traditional folklore (46), but minimal scientific or sociological evidence. In the same Finnish cohort discussed above, there was found to be a strong association between frequent sauna bathing and a reduction of psychotic disorders after a median follow-up of 25 years (51), but this is the only longitudinal evidence currently available. Other studies have suggested a positive effect of mood from a Korean “jjimjilbang” sauna (52, 53), as well as reduction of pain intensity in chronic conditions such as hypertension headaches (54).…”