Sitting in a hot sauna raises your heart rate and widens your blood vessels, a bit like light exercise. The strongest data come from long-running Finnish studies, so treat the findings as promising, not proven.
Early evidenceUpdated Oct 2026 · 4 new studiesA traditional Finnish sauna is 80–100 °C with low humidity. In 10–20 minutes your skin temperature climbs to about 40 °C and your core rises by around 1 °C.
To dump heat, your blood vessels widen and your heart speeds up to 100–150 beats per minute, pumping much more blood to the skin. That's similar to the heart's response to brisk walking or light jogging. Afterwards, blood pressure drops below where it started for a while.
Heat also triggers heat shock proteins, which help other proteins keep their shape and protect cells from damage. Regular sessions may improve the flexibility of your arteries over time.
Illustration of typical changes at about 80 °C. Heart rate climbs like it does during brisk walking, and blood pressure dips after you leave.
Skin heats up quickly; core temperature rises by about 1 °C.
To 100–150 bpm, like moderate exercise, to carry heat to the skin.
Blood flows to the skin; blood pressure falls after the session.
Heat shock proteins rise and help cells repair damaged proteins.
Categories from the Finnish Kuopio study (Laukkanen 2015).
2,315 Finnish men, 20 years
Compared with once a week, 2–3 sessions meant 24% lower death risk and 4–7 sessions meant 40% lower. Sessions over 19 minutes were linked to lower sudden cardiac death than sessions under 11.
Find on PubMed ↗2,315 Finnish men
4–7 sessions a week was linked to 66% lower risk of dementia and 65% lower risk of Alzheimer's disease.
Find on PubMed ↗1,628 Finnish adults
Frequent sauna users (4–7 times a week) had about 60% lower risk of stroke.
Find on PubMed ↗20 young sedentary adults
8 weeks of regular hot-water immersion improved artery function and lowered blood pressure.
Find on PubMed ↗Review
Evidence points to benefits for blood pressure, artery stiffness and inflammation, but it's mostly observational; randomised trials are needed.
Find on PubMed ↗A 2025 review of 51 studies confirms that regular heat therapy lowers blood pressure by a few points. Hot-tub soaking may raise body temperature more than a sauna, and heat adds blood vessel benefits on top of exercise but does not replace it. Cold plunge evidence is still mostly tiny lab studies.
Every study added to this page since January 2025. Green rings are the strongest evidence: large trials or meta-analyses.
Steward et al., 2025, 24 inactive adults aged 45 to 60, 8 weeks of exercise followed by 30 minutes in 40°C or lukewarm water. Drop in blood pressure.
51 studies, 1,055 people
Repeated heat sessions (sauna or hot water) lowered systolic blood pressure by about 5 mmHg and diastolic by about 3 mmHg. Arterial stiffness and inflammation (CRP) did not change.
24 inactive adults aged 45 to 60, 8 weeks
Adding 30 minutes in a 40°C hot tub after exercise cut systolic blood pressure by 8 mmHg, versus 3 mmHg with lukewarm water, and improved artery function. Fitness, blood sugar and cholesterol improved no more than with exercise alone.
20 young active adults
Soaking in a hot tub raised core body temperature more than a dry or infrared sauna, and was the only method to trigger an immune response. Not all heat is equal.
10 healthy young men, 7 days
After a week of daily one-hour dips in 14°C water, markers of cell clean-up (autophagy) in blood cells rose and cell-stress signals settled. On day one stress signals spiked, so the body needs time to adapt.
Regular heat, whether sauna or a hot bath, can take a few points off blood pressure, and adds to exercise rather than replacing it. Ice baths are mostly untested in people beyond tiny lab studies.
If you enjoy it, sauna is a pleasant extra. It doesn't replace exercise.
5–10 minutes at 70–80 °C, building to 15–20 minutes over a few weeks.
More frequent sessions were linked to the biggest benefits.
Drink water before and after. You can lose 0.5 litres of sweat in a session.
A lukewarm shower and a few minutes' rest. Cold plunges are optional; their benefits are less clear.
Alcohol plus heat is linked to fainting, heart rhythm problems and sauna deaths.
You have unstable chest pain, a recent heart attack, severe aortic stenosis, very low blood pressure, or are pregnant.
✕ MythYou sweat out toxins.
✓ FactSweat is mostly water and salt. Your liver and kidneys handle toxins.
✕ MythSauna can replace exercise.
✓ FactIt mimics some heart effects but doesn't build muscle, bone or fitness in the same way.
✕ MythHotter and longer is always better.
✓ FactBenefits were seen at normal sauna temperatures and 15–20 minutes. Extreme heat raises risk.
Some people find it relaxing after training. Evidence for faster recovery is limited.
For people with stable heart disease it's usually well tolerated, but get your doctor's advice first.
They may help mood and alertness, but evidence for long-term health benefits is much weaker than for sauna.
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Regular sauna use is linked to lower heart disease risk in Finnish men.
Regular sauna use is linked to lower heart disease risk in Finnish men.
Laukkanen 2015 (2,315 men): 4–7 sessions a week was linked to about 50% lower risk of fatal heart disease than 1 a week.
Sauna directly causes longer life.
Sauna directly causes longer life.
The big studies are observational in Finland, where sauna is part of daily life. Trials show better blood pressure and vessel function, but not lifespan yet.
You sweat out toxins in a sauna.
You sweat out toxins in a sauna.
Sweat is mostly water and salt. The liver and kidneys do the detox work.
A sauna session raises heart rate as much as moderate exercise.
A sauna session raises heart rate as much as moderate exercise.
Heart rate often reaches 100–150 bpm, which is part of why it's been called 'passive cardio'.
Drinking alcohol in the sauna is dangerous.
Drinking alcohol in the sauna is dangerous.
It raises the risk of low blood pressure, heart rhythm problems and fainting; many sauna deaths involve alcohol.
Hot baths have similar benefits to sauna.
Hot baths have similar benefits to sauna.
Japanese studies link frequent hot baths to lower heart risk too, but the evidence is thinner.
Cold plunges after sauna are proven to add years to your life.
Cold plunges after sauna are proven to add years to your life.
Cold exposure can boost mood and alertness, but there's no good evidence it extends life.
Heat exposure triggers heat shock proteins that help repair damaged proteins.
Heat exposure triggers heat shock proteins that help repair damaged proteins.
This is well shown in cells and animals and is one proposed reason for sauna's benefits.
Sauna lowers blood pressure in the short term.
Sauna lowers blood pressure in the short term.
Trials show readings drop after a session, and regular use is linked to lower long-term risk of hypertension.
Sauna is unsafe for everyone with heart disease.
Sauna is unsafe for everyone with heart disease.
For people with stable heart disease it's usually safe in moderation, but unstable angina, recent heart attack or severe aortic stenosis are exceptions. Ask your doctor.
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