Sauna and heat therapy · what one cohort found, and what trials tested
Plate 43
Heat record
What a study heated
35
Sources on the page
9
Goals in people
On this page. Counts, not a grade and not a ranking.
No goal on this page meets the rule for a stronger record. The rule is printed above the goals, and the count it read is printed under each one.
Read this first
Educational use only. This page is not medical advice. Temperatures, session lengths and frequencies are what a study ran or what a cohort reported, not a setting for you. Heat with alcohol, heart disease, low blood pressure, pregnancy or fertility plans is a question for your own clinician. Aaron Cuha is a coach, not a doctor.
Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.
A sauna heats the body with hot air: a Finnish sauna at about 80 to 90 C with low humidity, or an infrared cabin at a lower air temperature, about 43 to 60 C in the studies here. Heat therapy in the research also means sitting in a hot bath at about 39 to 40.5 C, which raises core temperature faster than air.
Most of what is written about sauna and longevity traces to the Kuopio Ischaemic Heart Disease study in eastern Finland. Its first sauna paper followed 2315 men for a median 20.7 years. Later papers from the same study added stroke, high blood pressure, lung disease, psychosis and dementia. Each is an association in people who chose how often to bathe.
The trials ask narrower questions over weeks, not decades: does heat lower blood pressure, widen arteries, help a failing heart, or add to training. This page reports those answers separately from the cohort, and the animal work in a section of its own.
The proposed story is that heat makes the heart and vessels work as if exercising, and that regular exposure trains them. Some of that is measured in small trials. Some is inferred from the cohort. This section says which is which.
Heat trains blood vessels
In 20 young sedentary adults, 8 weeks of hot water immersion raised flow-mediated dilatation from 5.6 to 10.9 percent and cut aortic stiffness, while a thermoneutral sham changed nothing. That was a hot bath held at a core temperature target, not a sauna.
More blood volume
In 6 male runners, 3 weeks of sauna after training raised plasma volume 7.1 percent and run time to exhaustion 32 percent against control, and the two moved together. Six people, in one crossover.
The cohort investigators' list
The Kuopio investigators propose better endothelial function, lower arterial stiffness, autonomic changes, lipid changes and lower blood pressure to explain their associations, and name these as areas of outstanding uncertainty.
Where the mechanism story is weak
41 adults with stable coronary disease used a Finnish sauna 4 times a week for 8 weeks. They acclimated to heat, but artery function, stiffness and blood pressure did not improve against control.
In 41 adults with untreated hypertension, 30 sessions of heat therapy left 24-hour systolic pressure at 134 mmHg before and after. Aerobic exercise did no better.
In 10 healthy women, 45 minutes in an infrared sauna raised body temperature but did not change blood pressure, arterial stiffness or heart rate variability against rest. The authors call its effects thermal rather than exercise-like.
Every number here is what a study ran or a cohort reported, named beside it. None is a setting for a reader. Air temperature, water temperature and core temperature are three different things, and the studies use all three.
Each row is a record from a paper or a cohort. It is not a plan for you.
| Goal | Who | What the trial ran | Source |
|---|---|---|---|
| Heart deaths, cohort | 2315 Finnish men aged 42 to 60 | Self-reported sauna habits: 1, 2 to 3, or 4 to 7 sessions a week, followed a median 20.7 years. | PMID 25705824 |
| Coronary disease, vessels | 41 adults with stable coronary disease | Finnish sauna 4 times a week for 8 weeks, 20 to 30 minutes at 79 C and 13 percent humidity, or lifestyle maintenance. | PMID 37650138 |
| Heart failure | 76 treated and 73 control patients with advanced heart failure | Infrared sauna at 60 C for 15 minutes, then 30 minutes of rest under a blanket, once a day for 10 days. | PMID 27001189 |
| Fitness and blood pressure | 47 inactive adults averaging 49 | 8 weeks of guideline exercise followed by 15 minutes of sauna, against exercise alone or control. | PMID 35785965 |
| Blood vessels, hot water | 20 young sedentary adults | Immersion in a 40.5 C bath for 60 minutes, 4 to 5 times a week for 8 weeks, against a thermoneutral sham. | PMID 27270841 |
| Sperm | 10 men with normal sperm | Two 15-minute Finnish sauna sessions a week at 80 to 90 C for 3 months, then 6 months off. | PMID 23411620 |
Stronger records first. Nulls and marketing-ahead goals stay on the same page. Every card is people only; animal work is in its own section below. Nothing here is ranked against the others, and no clinic or device is recommended.
How the tier is decided, so you can check it against the counts printed under each one. Stronger: a clinical guideline or a medical society's indication list recommends it in a named setting, or a pooled analysis of randomised trials favours heat and the source rated the certainty moderate. Thin: the pooled result was null or went against heat for the goal as named, the source rated it very low, or nothing was pooled at all. Mixed: everything else, including a result that moved one measure and not another.
Mixed, local, or early
15 studies pooled; certainty moderate; result mixed
Who was studied
A 2021 meta-analysis of 15 studies in healthy and clinical groups, most using hot water. Then randomised trials: 41 adults with coronary disease in a Finnish sauna, 41 with untreated hypertension, 22 with leg artery disease, and 20 young sedentary adults in hot water.
The meta-analysis found systolic pressure 3.94 mmHg and diastolic 3.88 mmHg lower than control, with moderate certainty. The young adults' hot water trial cut mean arterial pressure from 83 to 78 mmHg. The leg artery trial cut systolic pressure 7 mmHg. But the coronary disease sauna trial and the untreated hypertension trial found no change against control.
Setting in the evidence
Mostly hot water immersion at 39 to 40.5 C; Finnish sauna at 79 C in the coronary trial.
What this does not show
That a sauna habit treats high blood pressure. The pooled effect is a few points, mostly from hot water, and the trial in people with untreated hypertension was null.
Mixed, local, or early
7 studies, randomised and not, pooled; certainty mixed; result favours heat
Who was studied
Patients with chronic heart failure, mostly in Japan. A 2018 meta-analysis pooled seven infrared studies. The largest trial, WAON-CHF, randomised 76 hospitalised patients to infrared sauna and 73 to usual care, all with advanced heart failure, at 19 centres.
The meta-analysis found lower BNP, smaller heart size and better ejection fraction after 2 to 4 weeks, with strength of evidence moderate to insufficient. In WAON-CHF, symptom class, 6-minute walk and heart size improved, but the primary BNP measure did not reach significance; no serious adverse events.
Setting in the evidence
Infrared Waon therapy at 60 C for 15 minutes, then 30 minutes of warm rest, in hospital.
What this does not show
Longer-term outcomes such as survival or readmission, or anything about a hot Finnish sauna in heart failure.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
2315 middle-aged men in eastern Finland who reported how often and how long they bathed, followed for a median 20.7 years. Observational: the men chose their own habits. No trial has tested sauna against death.
Against one session a week, men reporting 4 to 7 had a hazard ratio for sudden cardiac death of 0.37 after adjustment for heart risk factors, with similar associations for fatal heart disease and death from any cause. Sessions over 19 minutes went with lower cardiac death but not lower all-cause death.
Setting in the evidence
Traditional Finnish saunas, as the men used them at home.
What this does not show
That sauna caused the difference. Men who bathe daily in Finland may differ in health, wealth and habits in ways adjustment misses. Women were not in this paper, and no trial has measured lifespan.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
The same 2315 Finnish men, median follow-up 20.7 years, 204 dementia diagnoses. Observational.
Against one session a week, 4 to 7 sessions had a hazard ratio of 0.34 for dementia and 0.35 for Alzheimer's after adjustment. 2 to 3 sessions did not differ significantly from one.
Setting in the evidence
Traditional Finnish saunas at home.
What this does not show
That heat protects the brain. No trial in people has tested sauna for memory or dementia. The mouse work on tau is in the animal section and does not make this card stronger.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
34 adults with major depression and no medication, randomised to one session of whole-body hyperthermia from a medical device or a matched sham; 29 analysed. A secondary analysis of 26 looked at IL-6. The secondary analysis' authors declare drug and wearable company roles.
Depression scores were 6.53 points lower than sham at week 1 and 4.27 lower at week 6. A rise in the IL-6 signalling ratio right after the session went with lower scores later.
Setting in the evidence
A medical whole-body hyperthermia device, one session.
What this does not show
That a sauna habit treats depression. This was one session of a device raising core temperature under supervision, in 29 people.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
47 inactive adults with a heart risk factor in a three-arm trial; 38 of them for heart rate variability; 6 runners; 16 basketball players; and a 2025 review of 14 studies in 194 healthy adults, funded in part by the Finnish Sauna Society.
Adding 15 minutes of sauna to 8 weeks of exercise gave 2.7 mL/kg/min more fitness gain and 8.0 mmHg lower systolic pressure than exercise alone, with no heart rate variability benefit. The runners ran 32 percent longer to exhaustion. Infrared after strength work reduced soreness. The review found acute recovery results split 4 positive, 4 null, 1 adverse.
Setting in the evidence
Finnish or humid sauna after training; infrared at about 43 C for recovery.
What this does not show
A reliable training effect. The review judged the evidence low to moderate and too varied to pool.
Thin, null, or marketing ahead
14 studies pooled; certainty not graded by the source; result null
Who was studied
14 articles from a search for randomised trials of passive heating in people with and without diabetes, and a separate pool of 5 studies in type 2 diabetes.
Without diabetes, heating did not change glucose control, and heating right after a glucose drink made glucose higher. In type 2 diabetes, HbA1c fell 0.549 percent and fasting glucose 0.290 mmol/l, neither significant.
Setting in the evidence
Hot water immersion and saunas of varied types.
What this does not show
Any proven benefit for blood sugar. The diabetes review's title says benefit; its pooled numbers do not reach significance.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
A 2020 review of 10 articles in healthy animals and adults. Its meta-analysis included animal samples only.
In people, the review found preliminary evidence that repeated heating may add muscle and strength, and a brief rise in corticospinal excitability after one session.
Setting in the evidence
Local and whole-body heating in varied forms.
What this does not show
Measured muscle gain in people from a sauna. The animal result is reported in the animal section.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Who was studied
Papers from the same Kuopio study: 1628 men and women for stroke, 1621 men for new high blood pressure, 1935 men for lung disease, 2138 men for psychotic disorders. All observational.
Against one session a week, 4 to 7 sessions had hazard ratios of 0.38 for stroke, 0.53 for new high blood pressure, and 0.21 for psychotic disorders; 4 or more had 0.59 for lung disease.
Setting in the evidence
Traditional Finnish saunas at home.
What this does not show
Cause. Every one of these is the same cohort design, from overlapping groups of the same men.
Animal and cell studies give heat a mechanism story: vessel enzymes, heat shock proteins, protection of muscle, less tau. They are here, apart from the people, because none of them is a human result.
Hamsters, infrared heat for 4 weeks
Daily infrared sauna at 39 C raised the vessel enzyme that makes nitric oxide by 50 percent in the aorta.
Rat heart failure model, 8 weeks of heat
Heat at 39 C prevented the fall in exercise tolerance seen in controls, from 441 to 344 seconds, and preserved heart pumping, with less fat and more lean mass.
Rats, unloaded hind limbs
One 60-minute bout of heat before 8 days of unloading reduced the loss of muscle weight and protein.
Animal meta-analysis, muscle
Pooled animal samples showed more muscle mass seven days after passive heating.
Rats, hot water after exercise
20 minutes at 41.2 C after leg exercise raised growth signalling but not ribosome production, a step in muscle growth.
Mice and cells, tau
Raising body temperature lowered tau phosphorylation, a marker of Alzheimer's pathology.
Obese mice, weekly heat
Heat sessions slowed weight gain and lowered inflammation and senescence markers in fat.
Roundworms, mild stress
Across 26 papers, mild stresses including heat extended mean lifespan by 16.7 percent. Worms, and not heat alone.
The longevity claim rests on one cohort. The Kuopio study is large, long and careful, but it is one population of mostly middle-aged Finnish men who chose their own habits. Its many sauna papers are not independent confirmations of each other.
The trials test something narrower. Over weeks, heat lowers blood pressure a few points on average, mostly in hot water studies, and helps heart failure patients on short-term measures with infrared. Two of the newest randomised trials, one in a Finnish sauna, found no vascular or blood pressure benefit.
Sauna as an add-on to exercise has one positive three-arm trial for fitness and blood pressure, and a null result for heart rate variability from the same design. A systematic review funded in part by the Finnish Sauna Society could not pool the recovery studies.
The measured harms are specific: reversible loss of sperm quality, and deaths that cluster in middle-aged men drinking alcohol and bathing alone.
The blocks above are the studies. The block below is a judgment about what to do with them. It has to say where it goes past the measurements.
Aaron Cuha’s position
This is opinion, not a finding. Everything else on this page is the evidence.
Regular sauna use is tied to fewer heart deaths and less dementia in one large Finnish cohort, and heat lowers blood pressure a few points on average across small trials. No trial has shown that sauna lengthens life or protects the brain, and the two newest randomised trials of heat for vessels and blood pressure were null.
The reasoning
Where this goes beyond the evidence
Calling the cohort an association and not a cause is a judgment: it is possible sauna does cause part of the difference, and a trial of decades is unlikely ever to be run. This position also goes beyond the evidence in treating the trial results as small: they are measured over 8 to 12 weeks, and what years of use do to blood pressure or vessels has not been tested in a randomised trial. If a long trial found fewer heart events with regular sauna, this position would be too cautious.
Who this is not for
Anyone who drinks before or during a sauna, anyone with unstable heart disease or fainting, anyone pregnant or trying to conceive who has not asked their own clinician, and anyone who wants this page to replace one.
Aaron Cuha, who built this archive and reads the studies behind the pages. He is a coach, not a doctor, and no medical credential is claimed for him anywhere on this site. More about who writes this
Anyone drinking
In 77 Swedish sauna deaths, 49 of 69 people tested had alcohol in the blood, and 34 deaths were related to alcohol.
Men trying to conceive
Two 15-minute sessions a week for 3 months markedly lowered sperm count and motility in 10 men. It reversed 6 months after stopping.
Anyone bathing alone with a heart condition
84 percent of the Swedish deaths were found in a sauna, all but 2 of them alone, and 18 deaths were related to heart disease.
Anyone wanting a personal protocol
Temperatures, durations and frequencies here are records of what a study ran or a cohort reported. They are not instructions for your body.
Of 77 sauna deaths in Sweden from 1992 to 2003, 82 percent were men, 49 of 69 tested were positive for alcohol, and 84 percent were found dead in a sauna, all but 2 of them alone.
Two 15-minute sessions a week at 80 to 90 C for 3 months markedly lowered sperm count and motility in 10 men and reduced sperm mitochondrial function from 76.8 to 54.0 percent. All of it reversed by 6 months after stopping.
A 1988 Finnish review concluded healthy pregnant women may bathe throughout pregnancy. It is a review from 1988, not a trial, and this page does not treat it as clearance for anyone.
WAON-CHF reported no serious adverse events among 76 treated and 73 control patients with advanced heart failure, with infrared at 60 C under hospital supervision. That is not a hot Finnish sauna at home.
This site teaches a blood panel, protein and training before gadgets. Sauna does not move that order. In the one trial that tested both, sauna was an add-on to exercise, not a replacement.
Disclosed both ways: the owner of this archive lists sauna in his own protocol at /my-protocols. That is a personal choice recorded there, not a finding on this page.
Nothing on this page is for sale. No seller wrote it, and no sauna or brand is named or ranked.
Four kinds of heat sold under the same idea. No brand is named, and none is ranked.
Hot dry air at about 80 to 90 C, with water on stones for brief humidity.
Evidence match. The Kuopio cohort, the coronary disease trial and the sperm study.
Mismatch. The cohort is an association, and the one Finnish sauna trial for vessels was null.
Infrared heaters warm the body at a lower air temperature, about 43 to 60 C in the studies here.
Evidence match. The Japanese heart failure trials, Waon therapy, and the basketball recovery study.
Mismatch. None of the Finnish cohort's results are about infrared, and infrared did not act like exercise in healthy women.
A bath or spa at about 39 to 40.5 C, which loads heat faster than air.
Evidence match. Most of the blood pressure meta-analysis, the young adults' vessel trial and the leg artery trial.
Mismatch. A hot bath is not a sauna; results do not transfer automatically.
A clinical device that raises core temperature under supervision.
Evidence match. The single-session depression trial.
Mismatch. Not a sauna habit, and one session in 29 analysed people.
Floor habits and the neighbouring pages. None of these is a cart.
Neighbour
The opposite stress, held to the same rule.
Floor
In the add-on trial, sauna helped alongside exercise.
Neighbour
Another recovery tool, goal by goal.
Floor
A marker, or a panel you still need. Not a diagnosis.
Disclosure
Where sauna appears in a personal plan, labelled as one.
Order
Measure first. Floor habits before gadgets.
Map
Every pillar, this one among them, held to the same rule.
Knowledge stays free. No seller wrote this page. Every source below opens the record that was checked before the sentence was written, with what it found and who funded it.
20 young sedentary adults, 8 weeks of hot water immersion at 40.5 C, 4 to 5 times a week, or a thermoneutral sham. Flow-mediated dilatation rose from 5.6 to 10.9 percent, aortic pulse wave velocity fell from 7.1 to 6.1 m/s and mean arterial pressure from 83 to 78 mmHg; the sham did not change. Hot water, not a sauna. Funded by the NIH heart institute.
6 male distance runners, crossover, 3 weeks of about 31 minutes of humid sauna after training. Run time to exhaustion rose 32 percent and plasma volume 7.1 percent against control. Six people. No funding or conflict statement in the PubMed record.
Narrative review by the cohort's own investigators. Proposes better endothelial function, lower arterial stiffness, autonomic changes, lipid changes and lower blood pressure as mechanisms, and lists areas of outstanding uncertainty. No funding or conflict statement in the PubMed record.
41 adults with stable coronary disease randomised to 8 weeks of Finnish sauna, 4 sessions a week at 79 C, or lifestyle maintenance. Bodies acclimated to heat, but flow-mediated dilatation, arterial stiffness and blood pressure did not improve against control. PubMed tags it as non-government funded; no conflict statement in the record.
41 adults with untreated high blood pressure randomised to 30 sessions of heat therapy or aerobic exercise over 8 to 10 weeks. 24-hour systolic pressure was 134 before and 134 after heat. Neither treatment lowered it. Funded by the American Heart Association, the NIH heart institute and the University of Oregon Foundation; the authors declare no conflicts.
10 healthy women, 45 minutes of rest, infrared sauna or cycling. The sauna raised ear temperature by 1.05 C over rest; it did not change blood pressure, arterial stiffness or heart rate variability. The authors conclude its effects are thermal, not exercise-like. No funding or conflict statement in the PubMed record.
Kuopio cohort, 2315 Finnish men aged 42 to 60, followed a median 20.7 years. Against one session a week, 4 to 7 sessions had a hazard ratio for sudden cardiac death of 0.37 after adjustment, and similar associations held for fatal heart disease and all-cause death. An observational association, not a trial. PubMed tags it as non-government funded; no conflict statement in the record.
Hospitalised patients with advanced heart failure at 19 centres, 76 randomised to 10 days of daily infrared sauna at 60 C for 15 minutes plus 30 minutes of rest under a blanket, and 73 to usual care. Symptom class, 6-minute walk and heart size on X-ray improved; the primary BNP ratio did not reach significance. No serious adverse events. PubMed tags it as non-government funded; no conflict statement in the record.
47 inactive adults averaging 49 with a heart risk factor, 8 weeks of exercise plus 15 minutes of sauna, exercise alone, or control. Against exercise alone, adding sauna gave 2.7 mL/kg/min more fitness gain, 8.0 mmHg lower systolic pressure and lower cholesterol. No conflicts declared.
10 men with normal sperm, two 15-minute sessions a week at 80 to 90 C for 3 months. Sperm count and motility fell markedly; sperm mitochondrial function fell from 76.8 to 54.0 percent. All effects reversed 6 months after stopping. No external funding; no conflicts declared.
Same cohort, 2315 men, median follow-up 20.7 years, 204 dementia cases. Against one session a week, 4 to 7 sessions had a hazard ratio for dementia of 0.34 and for Alzheimer's of 0.35. Men only, and an association. PubMed tags it as non-government funded; no conflict statement in the record.
15 studies, healthy and clinical groups, 30 to 90 minutes of heat over 10 to 36 sessions. Systolic pressure fell 3.94 mmHg and diastolic 3.88 mmHg against control, with moderate certainty; flow-mediated dilatation rose 1.95 percent with low certainty; resting heart rate did not change. No funding or conflict statement in the PubMed record.
22 people with leg artery disease, average ages 76 and 74 by group, randomised to 12 weeks of spa bathing at about 39 C or supervised exercise. Walking distance rose 41 m regardless of group; systolic pressure fell 7 mmHg after heat and 3 mmHg after exercise; no group difference in function. PubMed tags it as non-government funded; no conflict statement in the record.
Nine randomised and non-randomised studies, seven pooled, all infrared. Infrared sauna at 60 C for 15 minutes, five times a week for 2 to 4 weeks, was associated with lower BNP, smaller heart size and better ejection fraction; blood pressure did not change. Strength of evidence moderate to insufficient. No Finnish sauna study qualified. The authors declare no conflicts.
34 adults with major depression and no medication randomised to one session of medical whole-body hyperthermia or a sham, 29 analysed. Depression scores were 6.53 points lower at week 1 and 4.27 lower at week 6 than sham. One session of a device, not a sauna habit. No conflict statement in the PubMed record.
Secondary analysis of 26 people from the same trial. A rise in the IL-6 to soluble receptor ratio right after hyperthermia went with lower depression scores over 6 weeks. Funded by the NIH mental health institute; authors declare roles including chief scientific officer of a drug company, scientific advisor to a wearable company and consulting for drug makers.
38 participants from the same design. Adding 15 minutes of sauna after exercise gave no extra benefit on any heart rate variability measure over exercise alone. Funded by the Finnish Cultural Foundation; no conflicts declared.
16 male basketball players, randomised crossover, 20 minutes of infrared sauna at about 43 C or passive rest after strength training. The drop in jump height was smaller and soreness lower after the sauna; night-time heart rate variability did not differ. No conflicts declared.
14 studies, 194 healthy adults. Acute recovery results were uncertain: 4 no effect, 4 beneficial, 1 adverse. Repeated heat after training may help running in hot conditions but did not change cycling performance or VO2max. Too varied to pool. Grants listed from the Finnish Sauna Society and a sports institute foundation; no conflicts declared.
14 articles from a search for randomised trials of passive heating. Heating after a glucose drink made glucose higher, not lower; heating alone and a glucose test within 24 hours of heating showed no change in people without diabetes. No competing interests declared.
5 studies in type 2 diabetes. HbA1c fell 0.549 percent and fasting glucose 0.290 mmol/l, neither significant; triglycerides unchanged. The title says benefit; the pooled results were not significant. PubMed tags it as non-government funded; no conflict statement in the record.
10 articles in healthy animals or adults, four in the meta-analysis. In people, the review found only preliminary evidence that repeated heating may add muscle, and a short-lived rise in corticospinal excitability after one session. Its pooled result was in animals and is reported in the animal section. No conflict statement in the PubMed record.
1628 men and women aged 53 to 74 from the same study, median follow-up 14.9 years, 155 strokes. 4 to 7 sessions a week against one: hazard ratio 0.38 after adjusting for activity and income. The title says reduces; the design can only show an association. PubMed tags it as non-government funded; no conflict statement in the record.
1621 men without high blood pressure at baseline, median follow-up 24.7 years, 251 new cases. 4 to 7 sessions a week against one: hazard ratio 0.53 after full adjustment; 2 to 3 sessions, 0.83, not significant. No funding or conflict statement in the PubMed record.
1935 men, median follow-up 25.6 years, 379 cases of COPD, asthma or pneumonia. Hazard ratios 0.73 for 2 to 3 and 0.59 for 4 or more sessions a week against one or fewer. An association. PubMed tags it as non-government funded; no conflict statement in the record.
2138 men without psychotic disorders, median follow-up 24.9 years, 203 cases. 4 to 7 sessions a week against one: hazard ratio 0.21 after adjustment. An association in 184 frequent bathers. No funding or conflict statement in the PubMed record.
8 hamsters, infrared sauna at 39 C for 15 minutes daily for 4 weeks against a switched-off sauna. Endothelial nitric oxide synthase in the aorta rose by 50 percent. PubMed tags it as non-government funded; no conflict statement in the record.
27 obese rats with a model of heart failure, 8 weeks of 39 C heat or room temperature. Heat prevented the fall in exercise tolerance seen in controls (441 to 344 seconds) and preserved ejection fraction, with less fat and more lean mass. Grants listed from the American College of Sports Medicine and a private research trust.
Female rats, 10 a group. One 60-minute bout of heat before 8 days of hind limb unloading reduced the loss of soleus muscle weight and protein, with more heat shock protein 72. No funding or conflict statement in the PubMed record.
Rats, electrically stimulated leg exercise then 20 minutes of hot water at 41.2 C. Growth signalling rose, but ribosome production, a step in muscle growth, did not. Funded by the Japan Society for the Promotion of Science and a Japanese health research institute.
Normal and human-tau mice, and neuron-like cells. Raising body temperature lowered tau phosphorylation, a marker of Alzheimer's pathology. PubMed tags it as non-government funded; no conflict statement in the record.
Mice on normal or high-fat diets, four or eight weekly heat sessions. Heat raised muscle HSP70, slowed weight gain, normalised an insulin sensitivity index and lowered markers of inflammation and senescence in fat. No funding or conflict statement in the PubMed record.
26 papers on mild stress, heat among the stressors, in roundworms. Mild stress extended mean lifespan by 16.7 percent under normal conditions. Worms, and not heat alone. Funded by Chinese provincial and national science grants; no conflicts declared.
77 sauna-related deaths in Swedish medicolegal autopsies. 82 percent were men; 49 of 69 tested had alcohol in the blood; 34 deaths were related to alcohol and 18 to heart disease; 84 percent were found dead in a sauna, all but 2 of them alone. No funding or conflict statement in the PubMed record.
1988 Finnish review. Healthy pregnant women and healthy fetuses adapted to sauna heat; the authors concluded healthy pregnant women may bathe throughout pregnancy. A review from 1988, not a trial. No funding or conflict statement in the PubMed record.
Educational use only. This page is not medical advice. Temperatures, session lengths and frequencies are what a study ran or what a cohort reported, not a setting for you. Heat with alcohol, heart disease, low blood pressure, pregnancy or fertility plans is a question for your own clinician. Aaron Cuha is a coach, not a doctor.
Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.