The notion that sauna may support longevity is largely supported by a series of studies on a cohort of 2,315 middle-aged men in Finland, which found that sauna use was associated with a dose-dependent reduction in cardiovascular and all-cause mortality; people who used sauna the most (4–7 times per week for a duration of approximately 19 minutes or more per session) had a 50% reduction in risk for these outcomes.[1] A similar dose-dependent relationship was also present for sauna use and age-related neurodegenerative diseases like dementia and Alzheimer’s disease, with the most frequent sauna bathers having a 65% reduced risk of these conditions.[2]
Broadly speaking, it seems that sauna supports longevity in a similar way to exercise — by acting as a mild physiological stressor, it promotes cardiovascular, neurological, and immune function. In other words, it’s a hormetic stressor that promotes physiological responses that help bolster body systems that are most likely to falter during aging.
More specifically, the hormetic effects of sauna are the result of its influence on the following:[3]
- Heat shock protein expression: Sauna (and heat generally) increases cellular concentrations of heat shock proteins, a broad class of proteins that regulate a number of cellular processes related to gene expression and cell division and also recycle and repair other proteins that are damaged. There’s mechanistic evidence that they may help prevent neurodegeneration and muscle atrophy, and some observational research in humans has correlated heat shock protein levels with small (approximately 1 year) increases in lifespan.[4]
- Nrf2 activity: Nuclear factor erythroid 2-related factor (Nrf2) regulates antioxidant and immune functions in cells, and heat seems to increase its expression, at least in human skeletal muscle.[5]
- IL-6 and IL-10 activity: Similarly, sauna (and exercise) increases circulating levels of interleukin 6 and interleukin 10 (IL-6 and IL-10, respectively). The former is associated with increased inflammation, but it also increases levels of the latter, which has anti-inflammatory effects. Given that low-grade inflammation is a defining characteristic of many chronic diseases, it’s possible that sauna’s effect on inflammatory signaling may lead to ultimately more favorable levels of inflammation in the body.
References
- ^Laukkanen T, Khan H, Zaccardi F, Laukkanen JAAssociation between sauna bathing and fatal cardiovascular and all-cause mortality events.JAMA Intern Med.(2015-Apr)
- ^Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JASauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men.Age Ageing.(2017-Mar-01)
- ^Patrick RP, Johnson TLSauna use as a lifestyle practice to extend healthspan.Exp Gerontol.(2021-Oct-15)
- ^Singh R, Kølvraa S, Bross P, Christensen K, Bathum L, Gregersen N, Tan Q, Rattan SIAnti-inflammatory heat shock protein 70 genes are positively associated with human survival.Curr Pharm Des.(2010)
- ^Ihsan M, Deldicque L, Molphy J, Britto F, Cherif A, Racinais SSkeletal Muscle Signaling Following Whole-Body and Localized Heat Exposure in Humans.Front Physiol.(2020)