TLDR

Make the most of the findings.

We rated 55 claims. The research backs these 14 ideas well enough to act on, and each comes with something to try.

You can act on these findings about heat

Heat · 01

58%

lower risk of cardiovascular death for Finnish men who were fit and bathed often

Frequent sauna bathers died of heart disease less often, and fit bathers did best.

Researchers in Finland followed 2,315 men for about 20 years. Those who took four to seven saunas a week died of heart disease at roughly half the rate of once-a-week bathers.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 ↗ Later papers with longer follow-up and broader groups found a smaller difference, and none in the fitter half of the men.Source 2 · 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 ↗Source 3 · 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 ↗

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Build a sauna habit you'll stick with, and keep exercising. Men who were fit and bathed often had a 58% lower risk of cardiovascular death than men who were neither.Source 3 · 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 ↗

On Sauna MonthlyFinns made the daily sauna a habit

Heat · 02

−8 mmHg

extra drop in systolic blood pressure when a sauna followed each workout

A sauna after exercise lowered blood pressure more than exercise alone.

In an eight-week trial, people who followed each workout with 15 minutes in a sauna ended with systolic pressure (the top number) 8 mmHg lower than people who only exercised.Source 4 · Randomized trialEffects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trialLee E, Kolunsarka I, Kostensalo J, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2022.Read the paper ↗PubMed ↗ Pooled trials of heat alone found smaller lasting drops or none.Source 5 · 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 ↗Source 6 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗

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Take your sauna after the workout. If you take blood pressure medicine, stand up slowly when you finish, since these drugs can make pressure drop further after bathing.Source 7 · ReviewHealth effects and risks of sauna bathingKukkonen-Harjula K, Kauppinen K. International Journal of Circumpolar Health, 2006.Read the paper ↗PubMed ↗

On Sauna MonthlyAn indoor sauna puts the heat down the hall

Heat · 03

79°C

average temperature in the Finnish saunas behind the long-term studies

The long-term health data come from hot, traditional saunas.

The Finnish men bathed at about 79°C for 14 minutes a session.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 ↗ In a head-to-head study, a traditional sauna raised core temperature by 0.4°C and a typical infrared session didn't move it.Source 8 · Crossover trialComparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalitiesAtencio JK, Reed EL, Wiedenfeld Needham K, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2025.Read the paper ↗PubMed ↗

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If you're buying for health, choose a sauna that reaches about 80°C. An infrared cabin has to run hotter than its usual 45–60°C to heat your body as much.Source 9 · Clinical trialFar‐infrared sauna exposure at 65°C elevates core temperatureJenkins EJ, Killick JA, Grimm SR, et al.. Experimental Physiology, 2026.Read the paper ↗PubMed ↗

On Sauna MonthlyWeigh infrared against a traditional sauna

Heat · 04

61 kcal

extra burned in an hour sitting in 40°C water (an hour of cycling burned 556)

Sitting in the heat burns a few dozen calories an hour, and the weight you lose is water.

In a lab study, an hour sitting in 40°C water burned 61 kcal more than resting, and an hour of moderate cycling burned 556 more.Source 10 · Crossover trialThe effect of passive heating on heat shock protein 70 and interleukin-6: A possible treatment tool for metabolic diseases?Faulkner SH, Jackson S, Fatania G, et al.. Temperature, 2017.Read the paper ↗PubMed ↗ Nobody has measured a dry sauna that carefully. When one trial measured body fat, a sauna after exercise made no difference beyond the exercise itself.Source 4 · Randomized trialEffects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trialLee E, Kolunsarka I, Kostensalo J, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2022.Read the paper ↗PubMed ↗

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Count the sauna as rest when you track calories, and weigh yourself before a session. If your watch logs a sauna as a workout, delete the entry.

On Sauna MonthlyA wearable can show your body adapting to heat

Heat · 05

of a day's urine lead turns up in half a liter of sweat

Your kidneys and gut do the detox, and sweat carries traces.

Half a liter of sweat carries about 8% of the lead that a day's urine removes.Source 11 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗Source 12 · BookDietary Reference Intakes for Water, Potassium, Sodium, Chloride, and SulfateInstitute of Medicine. National Academies Press, 2005.Read the paper ↗ A 2019 review of sweat physiology calls sweat a minor way to clear toxic substances compared with the kidneys and gut.Source 13 · ReviewPhysiology of sweat gland function: The roles of sweating and sweat composition in human healthBaker LB. Temperature, 2019.Read the paper ↗PubMed ↗

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Use the sauna for the heat, and drink water to replace what you sweat. If a clinic sells sweating as a way to clear metals, ask what it measured.

On Sauna MonthlyLearn to read infrared sauna marketing

Heat · 06

6 months

for sperm counts to recover after three months of regular saunas

Regular saunas lower sperm counts, and the drop reverses.

Ten men took two 15-minute sessions a week at 80–90°C for three months, and their sperm count and motility (how well sperm swim) fell. Every measured change had reversed six months after they stopped.Source 14 · Clinical trialSeminal and molecular evidence that sauna exposure affects human spermatogenesisGarolla A, Torino M, Sartini B, et al.. Human Reproduction, 2013.Read the paper ↗PubMed ↗

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If you're trying to conceive, talk to your doctor about pausing saunas and hot baths for a few months.

30°HSperm count

The cold water research backs these ideas

Cold · 07

103 g

of quadriceps gained with ice baths after lifting (309 g with light cycling instead)

Ice baths right after lifting slow your muscle gains.

Over 12 weeks, men who sat in 10°C water after every leg session added 103 g of quadriceps muscle. The comparison group cycled lightly instead and added 309 g.Source 15 · Randomized trialPost‐exercise cold water immersion attenuates acute anabolic signalling and long‐term adaptations in muscle to strength trainingRoberts LA, Raastad T, Markworth JF, et al.. The Journal of Physiology, 2015.Read the paper ↗PubMed ↗ A pooled analysis of trials points the same way, and cold water after endurance training showed no such cost.Source 16 · Meta-analysisThe Effects of Regular Cold-Water Immersion Use on Training-Induced Changes in Strength and Endurance Performance: A Systematic Review with Meta-AnalysisMalta ES, Dutra YM, Broatch JR, et al.. Sports Medicine, 2021.Read the paper ↗PubMed ↗

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If you lift for size or strength, keep cold water away from the minutes after training. Plunge on rest days or after cardio.

22°HBlunted gains

On Sauna MonthlyTime your plunge around your training

Cold · 08

0.3

points less soreness on a 0–10 scale after an ice bath

Cold water after hard exercise eases soreness a little.

Across the trials, ice baths after exercise cut soreness by about 0.3 points on a 0–10 scale. Water at 10–15°C for 10–15 minutes did best.Source 17 · Meta-analysisCan Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-AnalysisMachado AF, Ferreira PH, Micheletti JK, et al.. Sports Medicine, 2016.Read the paper ↗PubMed ↗

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Save the ice bath for days when soreness is what's holding you back, like the day before a race or a match.

30°HFaster recovery

On Sauna Monthly · $1,749.99Ice Barrel 500

Cold · 09

5 min

in 13.6°C sea water lifted mood as much as 20 minutes did

A few minutes of cold water lifts mood right afterward.

Students with low mood improved about as much after 5 minutes in 13.6°C sea water as after 20.Source 18 · Randomized trialImproved Mood Following Cold‐Water Immersion: A Comparison of Differing Exposure DurationsKelly JS, Davidson N, Delaney JP. Lifestyle Medicine, 2026.Read the paper ↗ None of the mood studies used a placebo, so expectation plays a part.

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Keep dips short if you're doing it for your mood, since five minutes did as much as twenty.

34°HBetter mood

On Sauna MonthlyThese cold plunge tubs are worth buying

Cold · 10

30 s

of cold at the end of a shower did as much as 90 seconds

The end of your shower is the cheapest place to try cold water.

In a Dutch trial of 3,018 adults, people who ended a warm shower with 30 to 90 seconds of cold took 29% fewer sick days off work, and the shortest dose did as well as the longest. The days they spent feeling ill didn't change significantly.Source 19 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗

Try this

Finish your shower with 30 seconds of cold for a month and see whether you like it.

On Sauna MonthlyRun the Nordic hot and cold cycle at home

Cold · 11

2–3×

rise in the stress hormone noradrenaline after each dip

A short, very cold dip sends noradrenaline up two- to threefold.

Twenty seconds in 0–2°C water raised noradrenaline two- to threefold after every swim for 12 weeks.Source 20 · Clinical trialEffects of long‐term whole‐body cold exposures on plasma concentrations of ACTH, beta‐endorphin, cortisol, catecholamines and cytokines in healthy femalesLeppäluoto J, Westerlund T, Huttunen P, et al.. Scandinavian Journal of Clinical and Laboratory Investigation, 2008.Read the paper ↗PubMed ↗ The famous 250% dopamine figure came from blood drawn after an hour in 14°C water.Source 21 · Clinical trialHuman physiological responses to immersion into water of different temperaturesŠrámek P, Šimečková M, Janský L, et al.. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗

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Use a plunge as a wake-up if you like it, and judge it by how you feel in the hour afterward.

74°HDopamine

On Sauna MonthlyCold plunge tubs range from ice barrels to chillers

A few rules keep heat and cold safe

Safety · 12

1 min

for the gasp and fast breathing of cold shock to settle

The first minute in cold water is the dangerous part.

Men new to 10°C water breathed 47 times a minute in their first 30 seconds.Source 22 · Clinical trialPermanence of the habituation of the initial responses to cold-water immersion in humansTipton MJ, Mekjavic IB, Eglin CM. European Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗ In lab studies, holding your breath under cold water set off irregular heartbeats in 62% to 82% of submersions.Source 23 · Review‘Autonomic conflict’: a different way to die during cold water immersion?Shattock MJ, Tipton MJ. The Journal of Physiology, 2012.Read the paper ↗PubMed ↗

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Keep your face out of the water and breathe through the first minute. Never hold your breath under cold water, and have someone nearby.

18°HCold shock

Safety · 13

1 in 2

Finnish sauna deaths from 1990 to 2002 involved alcohol

Half the people who died in Finnish saunas had been drinking.

Forensic records show alcohol in half of Finnish sauna deaths from 1990 to 2002.Source 24 · Case seriesDeath in Sauna*Kenttämies A, Karkola K. Journal of Forensic Sciences, 2008.Read the paper ↗PubMed ↗ In a small experiment, adding alcohol to a sauna dropped systolic pressure from 136 to 113 mmHg. The sauna alone left it where it started.Source 25 · Clinical trialAlcohol and sauna bathing: effects on cardiac rhythm, blood pressure, and serum electrolyte and cortisol concentrationsRoine R, Luurila OJ, Suokas A, et al.. Journal of Internal Medicine, 1992.Read the paper ↗PubMed ↗

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Keep alcohol out of the sauna, and stay out yourself the morning after heavy drinking. Don't let anyone who has been drinking bathe alone.

Safety · 14

4–8 wk

to wait after a heart attack before using a sauna, per a Finnish review

Heart patients and pregnant women should check with a doctor first.

In small studies, people with stable heart disease handled sauna sessions well. Finnish experts advise staying out for four to eight weeks after a heart attack and whenever chest pain is prolonged or unstable.Source 7 · ReviewHealth effects and risks of sauna bathingKukkonen-Harjula K, Kauppinen K. International Journal of Circumpolar Health, 2006.Read the paper ↗PubMed ↗ In pregnancy, the reassuring data cover up to 20 minutes at around 70°C.Source 26 · Systematic reviewHeat stress and fetal risk. Environmental limits for exercise and passive heat stress during pregnancy: a systematic review with best evidence synthesisRavanelli N, Casasola W, English T, et al.. British Journal of Sports Medicine, 2019.Read the paper ↗PubMed ↗

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If you have heart disease or you're pregnant, talk to your doctor or midwife before you start, and keep sessions shorter and cooler if you get the go-ahead.