The claim
“Sauna cuts your risk of dementia by 66%.”
Unsettled. The 66% comes from 8 cases of dementia among about 200 Finnish men who took four to seven saunas a week. A larger Finnish study by a different team found no link in its most frequent bathers. In that study, saunas above 100°C went with more dementia during the first 20 years.
Updated Sep 24, 2026 · 2 studies reviewed
A little human data and a plausible mechanism support it. Better trials have to come before anyone relies on it.
People say it in places like these
Rhonda Patrick's FoundMyFitness
Frequent sauna use reduced the risk of dementia and Alzheimer's, and more sessions meant a bigger drop.
See an example ↗Daily Mail headline
Elderly men who take frequent saunas are 66% less likely to be diagnosed with dementia.
See an example ↗Review articles
Four to seven saunas a week cut dementia risk by 66% and Alzheimer's risk by 65%.
See an example ↗
The research found this
The 66% comes from the same 2,315 Kuopio men behind the studies of sauna and death. In a 2017 paper the researchers linked their sauna answers from the 1980s to dementia diagnoses through 2013.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗ Over a median of 20.7 years, 204 men developed dementia, and 123 were diagnosed with Alzheimer's disease.
Ten percent of the weekly bathers were diagnosed with dementia (59 men). In the top group it was 4% (8 men).Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗ The researchers adjusted for age, smoking, alcohol, blood pressure and other heart risk factors. After that, the top group had a hazard ratio of 0.34 for dementia and 0.35 for Alzheimer's disease. A hazard ratio compares how often something happens in two groups, and those two ratios turned into the 66% and 65% that get quoted. At two or three sessions a week, the difference wasn't statistically significant, so it could have been chance.
The 65% for Alzheimer's disease comes from five diagnoses in the top group. The analysis behind the headline figures didn't account for physical activity or socioeconomic status. The paper's text says the results stayed similar when those were added, though the table doesn't show that analysis.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗
A different team followed 13,994 Finnish men and women who were aged 30 to 69 when they were examined in the 1970s. Over as long as 39 years, 1,805 of them developed dementia.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗ People who bathed 9 to 12 times a month had a 19% lower hazard than people who bathed four times or fewer. Those who bathed most, 13 to 30 times a month, showed no significant difference. In the first 20 years, the 9-to-12 group's hazard was 53% lower.
The same study flagged heat as a possible risk. In the first 20 years, saunas hotter than 100°C went with a hazard ratio of 2.04 for dementia. Over the full follow-up that fell to 1.14 and was no longer significant.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗ A 2024 master's thesis, which hasn't been peer reviewed, looked at 555 Kuopio men aged 54 to 61. It found no correlation between sauna frequency and scores on four tests of thinking skills, although men who used hotter saunas scored better on two of them.Source 3 · Web pageSauna bathing and cognitive functions in Eastern Finnish men: a prospective cohort studyRahinduwa BK. Rahinduwa BK, 2024.Read the page ↗
The dial reads 48°H for four reasons
How the reading adds up
6 + 18 + 16 + 8 = 48°H
EvidenceWhat kind of human evidence exists?
6/25Two Finnish studies followed people for years and took dementia diagnoses from national health registers.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗ Sauna has never been tested against dementia in a trial.
ConsistencyHave other studies found the same thing?
18/25The two studies disagree. The larger one followed 13,994 Finnish adults for up to 39 years, and people who bathed 13 to 30 times a month showed no significant difference from people who bathed four times or fewer.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
16/25The 66% is a hazard ratio of 0.34, and it comes from 8 cases in the top group.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗ The larger study's best result was a 19% lower hazard at 9 to 12 baths a month. Its authors wrote that the data allow no firm conclusions.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
DoseDoes the studied dose match how people use it?
8/25Both studies asked about ordinary Finnish habits. The frequency behind the 66% was the least common one among the Kuopio men. In the larger study, saunas hotter than 100°C went with twice the hazard of dementia in the first 20 years.Source 4 · Cohort studyAssociation Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality EventsLaukkanen T, Khan H, Zaccardi F, et al.. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
The claim drifts from the data here
The 66% hangs on eight diagnoses. The Kuopio men who bathed most were also fitter than weekly bathers and less likely to smoke.Source 4 · Cohort studyAssociation Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality EventsLaukkanen T, Khan H, Zaccardi F, et al.. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗ The paper reports no memory testing at the start, so there's no way to tell whether men with early memory problems had already cut back on saunas.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗
The authors' 2024 review repeats the 66% and cites the other Finnish study for a 53% lower risk. It leaves out that the same study found no link in the most frequent bathers and more dementia with saunas above 100°C.Source 5 · ReviewThe multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish saunaLaukkanen JA, Kunutsor SK. Temperature, 2024.Read the paper ↗PubMed ↗
A letter to Neurology argued that links with conditions as different as Alzheimer's disease and respiratory illness point to healthy people choosing saunas more than to any effect of the heat.Source 6 · ReviewReader response: Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort studyDippel DW, Fransen PS, Ikram MK. Neurology, 2019.Read the paper ↗PubMed ↗
Put it to use
If you use a sauna, keep it under 100°C. Hotter saunas went with more dementia in the first 20 years of the larger Finnish study.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗ The data on memory are too thin to make a sauna part of a plan to prevent dementia.
From our sister magazine
Sauna Monthly picks thermometers that show how hot your sauna runs
In the larger Finnish study, saunas above 100°C went with more dementia in the first 20 years. A thermometer at head height tells you whether yours runs that hot.
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Sauna Monthly picks the thermometers and backrests worth owning.
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Sauna Monthly turns the Finnish research into a buying brief
The piece walks through the long Finnish study and what it means for a home sauna.
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Fischer Sauna Thermometer and Hygrometer
People also ask
Does sauna prevent Alzheimer's disease?
The evidence is too thin to say. In Kuopio men, four to seven saunas a week went with a hazard ratio of 0.35 for Alzheimer's disease, and only five men in the top group were diagnosed.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗ No trial has tested sauna against Alzheimer's, and a larger Finnish study found no link with dementia in its most frequent bathers.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
How often should you use a sauna for brain health?
There's no settled answer, because the two Finnish studies disagree. The Kuopio study found its link at four to seven sessions a week. In the larger study, the only significant link showed up at 9 to 12 baths a month, and there was none at 13 to 30.Source 1 · Cohort studySauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish menLaukkanen T, Kunutsor S, Kauhanen J, et al.. Age and Ageing, 2017.Read the paper ↗PubMed ↗Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
Is a very hot sauna bad for your brain?
One large Finnish study raised that worry. Among 13,994 adults, saunas hotter than 100°C went with twice the hazard of dementia during the first 20 years. Over the whole follow-up the link was weaker and not statistically significant.Source 2 · Cohort studyDoes sauna bathing protect against dementia?Knekt P, Järvinen R, Rissanen H, et al.. Preventive Medicine Reports, 2020.Read the paper ↗PubMed ↗
Check these claims next
81°H
Hot air
“Sauna boosts BDNF and grows your brain.”
Two small studies of men found that hot water and a heated suit raised blood BDNF for a short while. The sauna itself hasn't been tested, and we found no study that tied heat to brain growth.
41°H
Unsettled
“Frequent sauna use cuts your stroke risk by 61%.”
The 61% comes from one Finnish study of 1,628 adults that found fewer strokes in people who took four to seven saunas a week than in weekly bathers. The group sizes and stroke counts are behind a paywall. A Japanese study of daily hot baths found a smaller link.
36°H
Likely
“Regular sauna use helps you live longer.”
One long-running Finnish study ties frequent sauna use to fewer deaths. The 2015 paper put the most frequent bathers' risk of death 40% lower, and later papers with longer follow-up and broader groups put it about 14% lower. The link didn't show up in the fitter half of the men or in the women the study added later.
We cited these sources
- 01Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JA. Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men. Age and Ageing. 2017;46(2):245-249. doi:10.1093/ageing/afw212 PMID 27932366
- 02Knekt P, Järvinen R, Rissanen H, Heliövaara M, Aromaa A. Does sauna bathing protect against dementia?. Preventive Medicine Reports. 2020;20:101221. doi:10.1016/j.pmedr.2020.101221 PMID 33088678
- 03Rahinduwa BK. Sauna bathing and cognitive functions in Eastern Finnish men: a prospective cohort study. Rahinduwa BK. 2024.
- 04Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine. 2015;175(4):542-548. doi:10.1001/jamainternmed.2014.8187 PMID 25705824
- 05Laukkanen JA, Kunutsor SK. The multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish sauna. Temperature. 2024;11(1):27-51. doi:10.1080/23328940.2023.2300623 PMID 38577299
- 06Dippel DW, Fransen PS, Ikram MK. Reader response: Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study. Neurology. 2019;92(4):205. doi:10.1212/WNL.0000000000006808 PMID 30665915