Sauna and psychosis: what one long Finnish study found
A long-running Finnish study linked frequent sauna use with far fewer diagnoses of psychotic disorders. It’s a striking, single finding from an observational study, not evidence that sauna prevents or treats psychosis.
The short version
Researchers followed 2,138 Finnish men with no history of psychosis for a median of 24.9 years, in the same eastern Finland cohort as our heart-health and dementia articles. Men who reported four to seven sauna sessions a week had far fewer diagnoses of psychotic disorders than men who went once a week. The difference was unusually large, and we found no sign this finding has been replicated elsewhere. The diagnoses came from a broad register category, and the study cannot show that sauna prevents or treats psychosis.
Keep in mind
A single, very large and unreplicated finding, from a broad register-based category of “psychotic disorders.” It is an association, not evidence of prevention or treatment, and it shares its cohort with our heart and dementia articles.
What they found
Men who reported four to seven sauna sessions a week had a much lower rate of psychotic-disorder diagnoses than men who reported one session a week: a hazard ratio of 0.21 (95% confidence interval 0.08 to 0.52) after adjusting for other risk factors.
In plain terms, diagnoses were markedly less common among the most frequent sauna users in this cohort. That is a large difference between groups being compared, not a personal risk estimate, and the confidence interval is wide.
The “psychotic disorders” category in this study was broad, drawn from hospital and cause-of-death registers. The researchers did not report a mechanism, and it is not clear how much overlap with dementia-related diagnoses (already linked to sauna use in the same cohort) contributes to this finding.
What this means for your practice
This is a striking question for researchers, not a mental-health treatment or prevention claim. Psychotic disorders are serious conditions, and nothing here suggests that sauna use, with KUUME or otherwise, prevents, treats or replaces care for one.
This does not establish a sauna routine to follow. If you or someone you know is affected by psychosis or another serious mental illness, that calls for a qualified clinician, not a sauna session.
Methods and limitations
What the researchers did
This analysis uses the same cohort as our heart-health and dementia articles: 2,138 middle-aged men in eastern Finland who took part in the Kuopio Ischaemic Heart Disease (KIHD) study, this time restricted to men with no prior diagnosis of a psychotic disorder. They were followed for a median of 24.9 years.
The researchers grouped the men by how often they said they used a sauna at the start of the study: once a week, two to three times, or four to seven times. During follow-up, 203 of the men were diagnosed with a psychotic disorder, recorded through national health registers.
Like the other KIHD analyses, this is observational: nobody was asked to change their sauna habits, and the comparison is between groups of men with different existing habits.
How much can this tell us?
This is a novel result: we found no sign that it has been repeated in another population. An unusually large effect size in a single observational study is a reason for real caution, not less.
These are the same men as in the heart-health and dementia articles, so this is not independent confirmation of anything. It is one more outcome measured in one group of Finnish men.
Only men took part, sauna habits were recorded once, and men who used the sauna often may have differed from others in ways the statistics could not fully capture, including early, undiagnosed symptoms that could affect both sauna habits and a later diagnosis.
What makes it useful
- A long follow-up: a median of 24.9 years
- Excluded men with a prior psychotic-disorder diagnosis at baseline
- The association held after adjusting for several other risk factors
What limits it
- Observational: an association, not evidence of prevention or treatment
- A single, unusually large finding with no known replication
- The same men as our heart-health and dementia articles
- A broad diagnostic category, and only men took part
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular sauna protects against psychotic disorders. Early signal
Very low certaintyLarge effectIllness and death
Psychotic disorders 79% fewer
Likely 48% to 92%
Fewer cases than the comparison group. The bar is the best estimate, the band behind it the likely range.
From the same participant group as 7 other articles in The Study, so we count them as one group of people.
Read the original
Laukkanen T, Laukkanen JA, Kunutsor SK. Sauna Bathing and Risk of Psychotic Disorders: A Prospective Cohort Study. Med Princ Pract. 2018;27(6):562-569.
DOI 10.1159/000493392 · PubMed 30173212