The claim
“Sauna activates the FOXO3 longevity gene.”
Hot air. We found no study that measured FOXO3 in people after a sauna or any other heat treatment. The claim joins an untested gene effect to a longevity link from one Finnish cohort.
Updated Sep 24, 2026 · 2 studies reviewed
Nothing solid supports it, or the evidence points the other way.
People say it in places like these
Rhonda Patrick's FoundMyFitness
Heat stress activates the longevity gene FOXO3.
See an example ↗Huberman Lab podcast
His heat episode ties heat exposure and longevity to the FOXO3 gene.
See an example ↗
The research found this
The claim has two steps: a sauna switches on FOXO3, and FOXO3 helps people live longer. We found no study in people that measured FOXO3 after a sauna or any other kind of passive heating, so the first step has never been tested.
Heat does change gene activity in the blood. In a depression trial, 17 genes were more active 30 minutes after a session of whole-body hyperthermia than after a sham, and heat shock protein genes were among them.Source 1 · Clinical trialWhole-blood transcriptomic response to whole-body hyperthermia in participants with major depressive disorderAkonom TN, Allen MA, Begay TK, et al.. Brain, Behavior, & Immunity - Health, 2026.Read the paper ↗PubMed ↗ The protein most studied after sauna heat gives mixed results. Blood heat shock protein 72 rose 48.7% on average after 30 minutes at 73°C in one study, and a meta-analysis of 51 controlled heating studies found heat shock proteins unchanged overall.Source 2 · Crossover trialHeat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in HumansIguchi M, Littmann AE, Chang SH, et al.. Journal of Athletic Training, 2012.Read the paper ↗PubMed ↗Source 3 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗
The longevity half comes from the Finnish KIHD cohort. Men who took four to seven saunas a week had a 40% lower hazard of death than weekly bathers over a median of 20.7 years, and the gap shrank to 14% with longer follow-up and broader groups.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 5 · Cohort studyInflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort studyKunutsor SK, Jae SY, Kurl S, et al.. European Journal of Epidemiology, 2022.Read the paper ↗PubMed ↗ Among the fitter half of the men, frequent sauna use showed no clear link with death.Source 6 · Cohort studyJoint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort studyKunutsor SK, Khan H, Laukkanen T, et al.. Annals of Medicine, 2018.Read the paper ↗PubMed ↗ None of these papers measured FOXO3.
A 2021 review in Experimental Gerontology called sauna a probable way to extend healthspan and pointed to large cohort studies. Those cohort data are analyses of the same Finnish men.Source 7 · ReviewSauna use as a lifestyle practice to extend healthspanPatrick RP, Johnson TL. Experimental Gerontology, 2021.Read the paper ↗PubMed ↗
The dial reads 95°H for four reasons
How the reading adds up
25 + 20 + 25 + 25 = 95°H
EvidenceWhat kind of evidence exists in people?
25/25We found no human study of sauna or passive heating that measured FOXO3. The nearest data show heat raising the activity of heat shock protein genes in the blood.Source 1 · Clinical trialWhole-blood transcriptomic response to whole-body hyperthermia in participants with major depressive disorderAkonom TN, Allen MA, Begay TK, et al.. Brain, Behavior, & Immunity - Health, 2026.Read the paper ↗PubMed ↗
ConsistencyHas the finding held up?
20/25With no studies there is nothing to replicate. The longevity half leans on one Finnish cohort, where the link with fewer deaths shrank as follow-up grew.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 5 · Cohort studyInflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort studyKunutsor SK, Jae SY, Kurl S, et al.. European Journal of Epidemiology, 2022.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
25/25The claim describes a gene effect that nobody has measured. The one sauna study of a protective protein found blood heat shock protein 72 up 48.7% on average, and the variation between people was wide.Source 2 · Crossover trialHeat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in HumansIguchi M, Littmann AE, Chang SH, et al.. Journal of Athletic Training, 2012.Read the paper ↗PubMed ↗
DoseDoes the studied protocol match how people use it?
25/25No sauna routine has been tested for FOXO3. The Finnish men behind the longevity numbers sat at about 79°C for 14 minutes a session.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 claim drifts from the data here
The two halves of the claim have never appeared in the same study. FOXO3 was measured in none of the Finnish sauna papers or in any sauna study we found, so the step from the hot room to the gene is a guess about mechanism.
After whole-body hyperthermia, heat shock protein genes and immune genes become more active in the blood.Source 1 · Clinical trialWhole-blood transcriptomic response to whole-body hyperthermia in participants with major depressive disorderAkonom TN, Allen MA, Begay TK, et al.. Brain, Behavior, & Immunity - Health, 2026.Read the paper ↗PubMed ↗ Whether FOXO3 joins them after an ordinary sauna has not been studied.
Put it to use
Leave FOXO3 out of your reasons for a sauna until someone measures it. If longevity is your aim, weigh the Finnish cohort data. In those men, fitness predicted survival more strongly than sauna use did.Source 6 · Cohort studyJoint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort studyKunutsor SK, Khan H, Laukkanen T, et al.. Annals of Medicine, 2018.Read the paper ↗PubMed ↗
From our sister magazine
Sauna Monthly covers the longevity research and heat shock proteins
Sauna Monthly · Guide
Sauna Monthly turns the Finnish research into a buying brief
The piece walks through the KIHD findings and what they imply for a home sauna.
Sauna Monthly · Guide
Heat-shock proteins take five minutes to explain
Sauna Monthly covers the cellular repair crew that heat switches on.
People also ask
Does sauna increase FOXO3?
Nobody knows yet. We found no study in people that measured FOXO3 after a sauna or other passive heating, although heat does raise the activity of heat shock protein genes in the blood.Source 1 · Clinical trialWhole-blood transcriptomic response to whole-body hyperthermia in participants with major depressive disorderAkonom TN, Allen MA, Begay TK, et al.. Brain, Behavior, & Immunity - Health, 2026.Read the paper ↗PubMed ↗
What does the evidence say about sauna and longevity?
In one Finnish cohort, men who took four to seven saunas a week died less often than weekly bathers, and the gap shrank from 40% to 14% with longer follow-up.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 5 · Cohort studyInflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort studyKunutsor SK, Jae SY, Kurl S, et al.. European Journal of Epidemiology, 2022.Read the paper ↗PubMed ↗ It is an association, and the longevity page covers its limits.
Check these claims next
74°H
Stretched
“Sauna switches on heat shock proteins that slow aging.”
One sauna study found blood heat shock protein 72 up 48.7% on average after 30 minutes at 73°C, and a review of 51 controlled heating studies found no change overall. No study in people has tied heat shock proteins from a sauna to slower aging.
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.
88°H
Hot air
“Regular cold exposure helps you live longer.”
Nobody has followed people who use cold water to see how long they live. Reviews of winter swimming find physiological changes in small groups, and they can't tell whether swimmers were healthier to begin with.
We cited these sources
- 01Akonom TN, Allen MA, Begay TK, Mason AE, Cole SP, Raison CL, et al.. Whole-blood transcriptomic response to whole-body hyperthermia in participants with major depressive disorder. Brain, Behavior, & Immunity - Health. 2026;54:101225. doi:10.1016/j.bbih.2026.101225 PMID 42004495
- 02Iguchi M, Littmann AE, Chang SH, Wester LA, Knipper JS, Shields RK. Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans. Journal of Athletic Training. 2012;47(2):184-190. doi:10.4085/1062-6050-47.2.184 PMID 22488284
- 03Price BS, Lucas SJE, Akerman AP, Gilworth RE, Lucas RAI. Heat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysis. Experimental Physiology. 2025:EP092404. doi:10.1113/EP092404 PMID 41166412
- 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
- 05Kunutsor SK, Jae SY, Kurl S, Kauhanen J, Laukkanen JA. Inflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort study. European Journal of Epidemiology. 2022;37(12):1225-1231. doi:10.1007/s10654-022-00926-w PMID 36255556
- 06Kunutsor SK, Khan H, Laukkanen T, Laukkanen JA. Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study. Annals of Medicine. 2018;50(2):139-146. doi:10.1080/07853890.2017.1387927 PMID 28972808
- 07Patrick RP, Johnson TL. Sauna use as a lifestyle practice to extend healthspan. Experimental Gerontology. 2021;154:111509. doi:10.1016/j.exger.2021.111509 PMID 34363927