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 ties that untested gene effect to a longevity link from one long-running Finnish study of men.
Updated Sep 24, 2026 · 2 studies reviewed
Nothing solid supports it, or the best evidence runs against it.
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 needs a sauna to switch on FOXO3 and FOXO3 to help people live longer. Our search found no study in people that measured FOXO3 after a sauna or any other heating without exercise, so the first step is untested.
Heat does change gene activity in the blood. In a depression trial, 17 genes were more active 30 minutes after a session of medical whole-body heating 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 proteins studied most often after sauna heat give mixed results. In one study, blood heat shock protein 72 rose 48.7% on average after 30 minutes at 73°C.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 ↗ A pooled analysis of 51 controlled heating studies found heat shock proteins unchanged overall.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 numbers come from a Finnish study called KIHD. Over a median of 20.7 years, men who took four to seven saunas a week had a 40% lower risk of death than weekly bathers.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 ↗ With longer follow-up and broader groups, that difference shrank to 14%.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 ↗
A 2021 review in Experimental Gerontology called sauna a probable way to extend healthspan (the years lived in good health). It pointed to large long-term studies, and those 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 human evidence exists?
25/25Nothing in the human research speaks to FOXO3 directly. 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 ↗
ConsistencyHave other studies found the same thing?
20/25With no studies there is nothing to replicate. The longevity half comes from one Finnish study of men, and its link with fewer deaths shrank the longer the men were followed.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 gene effect in the claim has never been measured, so it has no size to match. In the one sauna study of a protective protein, blood heat shock protein 72 rose 48.7% on average and varied widely between people.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 dose match how people use it?
25/25The Finnish men behind the longevity numbers used saunas 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 ↗ Whether any sauna routine touches FOXO3 is unknown.
The claim drifts from the data here
The two halves of the claim have never shared a study. FOXO3 doesn't appear in 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 how sauna might work.
After medical whole-body heating, 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 is an open question.
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 data on sauna and survival. 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 long Finnish study and what it means for a home sauna.
Sauna Monthly · Guide
Heat-shock proteins take five minutes to explain
Sauna Monthly explains the repair proteins that heat switches on inside your cells.
People also ask
Does sauna increase FOXO3?
That's unknown, because FOXO3 hasn't been measured in people after a sauna or any other heat treatment. 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 long-running Finnish study, men who took four to seven saunas a week died less often than weekly bathers, and later papers with longer follow-up and broader groups put the difference at 14%, down from 40%.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 shows 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.”
In one sauna study, blood levels of heat shock protein 72 rose 48.7% on average after 30 minutes at 73°C. A review of 51 controlled heating studies found no change overall, and the idea that these proteins slow aging comes from animal research.
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.
88°H
Hot air
“Regular cold exposure helps you live longer.”
There are no studies of how long cold-water users live. Reviews of winter swimming describe changes in the body among small groups of swimmers, and they can't tell whether the 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