Finnish men who took the most saunas had fewer deaths over twenty years
Most sauna longevity claims trace back to this 2015 paper in JAMA Internal Medicine. It followed 2,315 men in eastern Finland and compared men who took four to seven saunas a week with men who took one.
The paper
Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events
Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. JAMA Internal Medicine, 2015;175(4):542-548.
See the study at a glance
- Design
- Prospective cohort study
- People
- 2,315 men
- Who they were
- Researchers examined men aged 42 to 60 from Kuopio and the surrounding countryside between 1984 and 1989. About a quarter had heart disease at the start.
- What they did
- Each man filled in one questionnaire on how often he took a sauna, how long he stayed in and how hot the room was. The average man went twice a week for 14 minutes at 79°C.
- How long
- Median 20.7 years
These numbers came out of it
0.60
This hazard ratio means men who went four to seven times a week had a 40% lower risk of dying from any cause than men who went once.
62 of 201
Men in the most frequent group died during follow-up. That comes to 31% of the group, and 49% of weekly bathers died over the same years.
10
The widely quoted 63% drop in sudden cardiac death comes from this many deaths in the top group.
1.00
Once age was taken into account, men whose sessions ran past 19 minutes had the same risk of death from any cause as men who stayed under 11.
Hazard ratio with 95% confidence interval
Men who took four to seven saunas a week had lower risk on all four measures of death
These figures account for age, body mass index, blood pressure, LDL cholesterol, smoking, alcohol, previous heart attack, diabetes, measured fitness, resting heart rate, physical activity and socioeconomic status.
The researchers did this
Of 3,433 men picked at random from Kuopio and nearby rural areas, 2,682 took part in the Kuopio Ischaemic Heart Disease study. Each one filled in a questionnaire about his sauna habits at his first examination, and a nurse checked the answers.Source 1 · 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 ↗
This paper used the 2,315 men with complete sauna data. Only 12 men in the whole study never took saunas. They were left out, so men who went once a week became the comparison group. The researchers then tracked every man through national death registries until the end of 2011.
By then 929 men had died, and deaths fell with each step up in sauna use. Among the once-a-week men, 49% died. The share dropped to 38% at two or three sessions a week and to 31% at four to seven. The pattern held after the researchers accounted for fitness, smoking, blood pressure, socioeconomic status and other factors.
Session length made no difference to death from any cause. Once age was taken into account, men whose sessions ran past 19 minutes fared the same as men who stayed under 11, although longer sessions went with fewer sudden cardiac deaths.
A supplement to the paper breaks the result down by subgroup. The link with sudden cardiac death was strongest in men with diabetes and in men who already had heart disease. It didn't appear in the fittest third of men or in men who started out free of heart disease.
The study can't tell you these things
- The men chose their own sauna habits, so the study can only show a link. Frequent bathers were also younger and fitter than weekly bathers, and far fewer of them smoked.
- Only 201 men made up the top group. The headline ratios come from the 62 deaths and 10 sudden cardiac deaths among them.
- The men were asked about their sauna habits once. When 722 of them answered again eleven years later, their habits had changed enough to weaken any link measured from the first answer.Source 2 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗
- The men were all middle-aged Finns who grew up with saunas, and about a quarter already had heart disease. If illness made some men cut back, sauna use would look protective even if it did nothing.
- One table prints a hazard ratio of 0.83 with a confidence interval of 0.87 to 1.20. An estimate always falls inside its own interval, so that figure can't be right. The authors' 2018 review repeats it.Source 3 · ReviewCardiovascular and Other Health Benefits of Sauna Bathing: A Review of the EvidenceLaukkanen JA, Laukkanen T, Kunutsor SK. Mayo Clinic Proceedings, 2018.Read the paper ↗PubMed ↗
People quote it like this
Most of the sauna longevity numbers in circulation come from this paper. They usually show up as "40% lower risk of death" and leave out who the frequent bathers were compared with and how few men were in the top group. The journal's editor welcomed the paper warmly, and two letters later that year argued that a healthy lifestyle may explain the link.Source 4 · ReviewHealth Benefits of Sauna BathingRedberg RF. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗Source 5 · ReviewThe link between sauna bathing and mortality may be noncausalKivimäki M, Virtanen M, Ferrie JE. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗Source 6 · ReviewThe link between sauna bathing and mortality may be noncausalEpstein Y, Shoenfeld Y. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗
From our sister magazine
Sauna Monthly reviews saunas that reach the study's 79°C
We cited these sources
- 01Laukkanen 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
- 02Laukkanen JA, Mäkikallio TH, Khan H, Laukkanen T, Kauhanen J, Kunutsor SK. Finnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort study. European Journal of Cancer. 2019;121:184-191. doi:10.1016/j.ejca.2019.08.031 PMID 31590079
- 03Laukkanen JA, Laukkanen T, Kunutsor SK. Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence. Mayo Clinic Proceedings. 2018;93(8):1111-1121. doi:10.1016/j.mayocp.2018.04.008 PMID 30077204
- 04Redberg RF. Health Benefits of Sauna Bathing. JAMA Internal Medicine. 2015;175(4):548. doi:10.1001/jamainternmed.2014.8206 PMID 25706401
- 05Kivimäki M, Virtanen M, Ferrie JE. The link between sauna bathing and mortality may be noncausal. JAMA Internal Medicine. 2015;175(10):1718. doi:10.1001/jamainternmed.2015.3426 PMID 26436738
- 06Epstein Y, Shoenfeld Y. The link between sauna bathing and mortality may be noncausal. JAMA Internal Medicine. 2015;175(10):1718-1719. doi:10.1001/jamainternmed.2015.3429 PMID 26436739