The claim
“Sauna cuts your risk of dementia by 66%.”
Early. The 66% rests on 8 cases of dementia among about 200 Finnish men who took four to seven saunas a week. A larger, independent Finnish cohort found no link in its most frequent bathers, and saunas above 100°C went with more dementia in its first 20 years.
Updated Sep 24, 2026 · 2 studies reviewed
Some human data and a plausible mechanism. It needs better trials before anyone can lean 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 sauna mortality findings. 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.
Dementia was diagnosed in 10% of the weekly bathers (59 men) and in 4% of the men who went four to seven times a week (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 ↗ After adjustment for age, smoking, alcohol, blood pressure and other heart risk factors, the top group had a hazard ratio of 0.34 for dementia and 0.35 for Alzheimer's disease. Those ratios became the 66% and 65% figures in circulation. Two or three sessions a week made no significant difference.
The 65% figure for Alzheimer's disease rests on five diagnoses in the top group. The model behind the headline figures didn't include physical activity or socioeconomic status. According to the text, the results stayed similar when those were added, though the table doesn't show that model.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 ↗
An independent 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, and those who bathed 13 to 30 times showed no significant difference. In the first 20 years, the 9-to-12 group's hazard was 53% lower.
The same cohort flagged heat as a possible risk. Saunas hotter than 100°C went with a hazard ratio of 2.04 for dementia in the first 20 years, which fell to 1.14 and lost significance over the full follow-up.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 has not been peer reviewed, found no correlation between sauna frequency and four cognitive tests in 555 Kuopio men aged 54 to 61, 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 evidence exists in people?
6/25Two prospective cohorts followed people to dementia diagnoses in 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 ↗ Nobody has tested sauna against dementia in a trial.
ConsistencyHas the finding held up?
18/25The two cohorts disagree. In 13,994 Finnish adults followed for up to 39 years, 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 built on 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 cohort's best result was a 19% lower hazard at 9 to 12 baths a month, and 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 protocol match how people use it?
8/25Both cohorts measured ordinary Finnish habits. The frequency behind the 66% was the rarest in the Kuopio men, and in the larger cohort saunas hotter than 100°C were linked to 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
Eight diagnoses carry the 66%. The Kuopio men who bathed most were 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 is no way to tell whether men with early memory problems had already cut back.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 independent cohort for a 53% lower risk. It leaves out that cohort's null result in the most frequent bathers and its finding on 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 suggest healthy people choosing saunas more than an effect of 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, since hotter saunas went with more dementia in the first 20 years of the larger Finnish cohort.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 memory data are too thin to make a sauna part of a plan to prevent dementia.
From our sister magazine
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People also ask
Does sauna prevent Alzheimer's disease?
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 cohort 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?
The two Finnish cohorts point to different answers. The Kuopio study found its link at four to seven sessions a week, while the larger cohort found its only significant link at 9 to 12 baths a month and 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?
In a Finnish cohort of 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 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.”
No study has measured BDNF after a sauna, and we found none linking heat to brain growth. Hot water and a heating suit raised blood BDNF briefly in two small studies of men.
41°H
Early
“Frequent sauna use cuts your stroke risk by 61%.”
The 61% comes from one Finnish cohort of 1,628 adults, where people who took four to seven saunas a week had fewer strokes than weekly bathers. The group sizes and stroke counts sit behind a paywall, and a Japanese study of daily hot baths found a smaller link.
36°H
Likely
“Regular sauna use helps you live longer.”
One Finnish cohort ties frequent sauna use to fewer deaths. With longer follow-up the gap shrank from 40% to about 14%, and it disappeared in the fittest men and in women's heart deaths.
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