Direct answer
A sauna session asks something of your heart. Heart rate goes up. Blood vessels open. You lose fluid in sweat. For a healthy adult who already likes heat, that can be a reasonable habit. It has not been shown to prevent heart disease, and it is not a substitute for walking, lifting, or the tablets your GP prescribed.
The paper most often sitting under “sauna is good for your heart” is Laukkanen and colleagues in JAMA Internal Medicine, 2015: an observational follow-up of middle-aged Finnish men who already used a sauna. More frequent bathing was associated with lower rates of some fatal cardiovascular outcomes over about twenty years. Association is not proof that heat caused the difference.
A small eight-week randomised trial (Lee, 2022) found that adding a short sauna after guideline-based exercise was associated with a further drop in systolic blood pressure compared with exercise alone. The sauna sat on top of training, not instead of it.
Large, gold-standard randomised trials of sauna as a heart intervention are still missing. Dr Heather Massey said so on BBC News in December 2025 and again on The Guardian’s Science Weekly on 30 July 2026.
This page is the heart briefing. The wider evidence picture — what a Finnish sauna is, and the same papers in their broader context — lives on what the evidence says about regular sauna use.
Key facts
- Heat is a cardiovascular load, not a cardio class. Heart rate and cardiac output rise; skeletal muscle does not do the work of a walk or a lift. Do not skip exercise because you sat in a hot room.
- Laukkanen et al., JAMA Internal Medicine, 2015 (not 2018): 2,315 middle-aged men from eastern Finland; median follow-up 20.7 years. More frequent traditional sauna use was associated with lower sudden cardiac death, fatal coronary heart disease, fatal cardiovascular disease, and all-cause mortality after adjustment. Observational. Men. Almost no non-users. No randomised assignment. Not a treatment effect.
- Mayo Clinic Proceedings, 2018 is a narrative review of that evidence line, not the original 20-year follow-up.
- Lee et al., 2022: 47 sedentary adults, eight weeks. Exercise plus a 15-minute post-exercise sauna, three times a week, was associated with a further mean 8.0 mmHg drop in systolic blood pressure versus exercise alone (95% CI −14.6 to −1.4). Small. Short. Adjunct, not replacement. Not a licence to treat hypertension with heat.
- Massey, University of Portsmouth (BBC News, 30 Dec 2025; Guardian Science Weekly, 30 Jul 2026): there is not “the sort of gold standard data from large randomized controlled trials that we’d really like to see.”
- If you have heart disease, arrhythmia, uncontrolled blood pressure, or you are pregnant, speak to your GP before you heat the room. NHS-style advice still reproduced on GP sites: consider avoiding sauna, especially in the first 12 weeks of pregnancy. No alcohol in the room.
- Two or three sessions a week is a reasonable habit for a healthy adult who already likes it. That figure is not a medical dose.
- In a UK garden, whether the room still holds heat in January is a construction question: 200mm wall thickness with 100mm insulation. That is insulation. It is not a heart claim.
Evidence at a glance
| Question | What the evidence actually is | Evidence level |
|---|---|---|
| Does frequent sauna use prevent cardiovascular death? | In Finnish observational follow-up of middle-aged men (Laukkanen, JAMA Intern Med, 2015), more frequent traditional sauna bathing was associated with lower fatal cardiovascular rates. Not a randomised trial. Not women. Not a UK cohort. | Observational |
| Does sauna lower blood pressure? | Lee 2022: a small eight-week trial found a further mean 8.0 mmHg drop in systolic BP when a short sauna was added after guideline-based exercise, versus exercise alone. Not a hypertension treatment. Not a long-term outcome trial. | Small randomised trial (adjunct) |
| Does sauna replace aerobic exercise? | No. Heat raises heart rate without the skeletal-muscle work of training. Lee 2022 put the sauna on top of exercise; the training still did the fitness work. | Small randomised trial + physiology |
| Did Mayo 2018 settle the heart question? | No. It is a 2018 narrative review. Regular Finnish sauna may be linked with some vascular outcomes; most long-term data were still observational; more work needed. | Expert advice (narrative review) |
| Are there gold-standard RCTs of sauna for the heart? | Massey (BBC, Dec 2025; Guardian Science Weekly, 30 Jul 2026): large randomised trials are not there yet. | Expert advice |
| Is sauna safe for everyone with a heart condition? | Heat is a load. People with heart disease, arrhythmia, uncontrolled blood pressure, a recent heart attack or stroke, or who are pregnant, should speak to a GP first. Alcohol does not belong in the room. | Expert advice / safety |
What a session actually does to circulation
You sit down. The room is hot. Skin vessels open, you sweat, and the heart speeds up to keep blood pressure and temperature in a workable range. Cardiac output rises. That is a real demand. It is also not a training session.
A walk, a lift, or a bike uses skeletal muscle. The heart adapts, in part, because the body is doing work. A sauna does not give you that work. Heart rate in the heat can look “like exercise” on a wrist tracker. The tracker is counting beats, not a workout.
Some studies report acute changes in blood pressure and in measures of how the vessel lining behaves. Those are interesting physiology papers. They are not proof that regular heat prevents a heart attack, and they are not a reason to come off blood-pressure tablets.
If the session feels like too much — tight chest, dizziness you cannot talk down, feeling not yourself — get out, cool steadily, sit, drink water. That is not toughness. That is the load speaking.
The Finnish association is not a treatment effect
The cohort paper is Laukkanen and colleagues, JAMA Internal Medicine, 2015 — not 2018.
They followed 2,315 middle-aged men from eastern Finland, drawn from the Kuopio Ischemic Heart Disease Risk Factor Study. Baseline examinations ran from 1984 to 1989. Median follow-up was 20.7 years. Men were grouped by how often they reported sauna bathing at the start: once a week, two to three times, or four to seven times.
After adjustment for a long list of cardiovascular risk factors, more frequent sauna use was associated with lower rates of sudden cardiac death, fatal coronary heart disease, fatal cardiovascular disease, and all-cause mortality. Longer sessions were also associated with lower sudden-cardiac-death rates.
That is serious epidemiology. It is still a photograph of Finnish men who already sat in heat, already lived in a sauna culture, and who may differ in ways no questionnaire fully captures. There was no randomised assignment. There were almost no non-users. The sample was men.
The headline percentages from that cohort — 50%, 40%, 27% — are adjusted associations. They are not a treatment effect, not a UK result, and not a dose we will sell.
The longer reading of the same paper, and of what a Finnish sauna actually is, sits on the overview.
Mayo 2018 organised the evidence. It did not settle it.
In August 2018, Laukkanen, Tanjaniina Laukkanen and Setor Kunutsor summarised the evidence in Mayo Clinic Proceedings. They wrote that regular Finnish sauna bathing may be linked with lower risk of some vascular outcomes, and they set out postulated mechanisms. They also flagged uncertainty. Most of the long-term outcome data were still observational. Randomised trials were few and small.
That review is often cited as if it were the original 20-year follow-up, or as if it closed the question. It is a review. It organised what existed and said, politely, that more work was needed.
The blood-pressure trial put sauna on top of exercise
The trial people mean when they talk about blood pressure and sauna is Earric Lee and colleagues, 2022, in the American Journal of Physiology.
Forty-seven sedentary adults, mean age 49, with at least one traditional cardiovascular risk factor, were randomised for eight weeks to guideline-based exercise plus a 15-minute post-exercise sauna three times a week; to the same exercise without sauna; or to a control group.
Exercise alone improved fitness against control. Adding the sauna was associated with a further mean reduction in systolic blood pressure of 8.0 mmHg compared with exercise alone (95% CI −14.6 to −1.4).
Read that slowly. Small trial. Eight weeks. Forty-seven people. The sauna sat on top of exercise, not instead of it. Systolic pressure moved; this is not a trial of heart attacks, strokes, or death. It is not a reason to treat high blood pressure with heat, and it is not a reason to skip the walk.
If your blood pressure is the thing you are trying to change, the conversation still starts with your GP, not with a thermometer.
The trials we do not have
On 30 December 2025, Dr Heather Massey of the University of Portsmouth’s Extreme Environments Laboratory told BBC News: “There are a lot of people who swear by hot and cold exposure, but we don’t yet have sufficient evidence to say it’s categorically good for you.” And: “We’ve never really done a proper sauna trial. I suspect we’ll find benefits in the future, but we’re not there yet.”
On 30 July 2026, The Guardian’s Science Weekly re-aired a conversation from 2 April. Massey’s line then was that we do not have “the sort of gold standard data from large randomized controlled trials that we’d really like to see.”
That is the honest ceiling for this page. Observational Finnish follow-up is a signal. One small blood-pressure trial is an adjunct finding. Neither is a prevention protocol. Neither is a replacement for movement, sleep, or clinical care.
She advises easing in gradually, and speaking to a GP first if you have an underlying condition or are pregnant. Heat is a cardiovascular load. People have come to harm — rarely, and often with alcohol or existing disease in the picture.
None of that makes sauna reckless for a healthy adult who builds up slowly, stays hydrated, and leaves alcohol outside the door. It does make “clinically proven for your heart” a phrase we will not use.
A working pattern (healthy adults who already like it)
This is a starting pattern for a healthy adult who already enjoys heat. It is not a cardiac protocol and not personal medical advice.
- Heat. About 8–15 minutes, around 80–90°C to begin with. Sit down. Breathe. Get out while you still feel in charge. Leave sooner if you feel light-headed, sick, tight in the chest, or not yourself.
- Cool. Air or a lukewarm shower. A cold plunge is a separate cardiovascular load. If that is the ritual you want, read sauna and cold plunge, and speak to your GP first if you have heart or blood-pressure issues. Do not plunge alone.
- Water in. Alcohol out. Drink. Do not use a sauna after alcohol. Heat plus alcohol is how ordinary sessions turn into emergency ones.
- How often. Two or three sessions a week is a habit many people keep. Four to seven times a week was a reporting group in the Finnish cohort, not a dose. Daily use is not a proven “more is better” protocol for the heart.
- Build up. Beginners can start cooler and shorter (70–80°C, five to ten minutes).
Whether a UK garden room still holds that heat in January is a construction question: 200mm wall thickness with 100mm insulation. That is how a properly insulated outdoor sauna is built for this climate. It is not evidence that insulation protects a heart.
Who should see a GP
Heat is a cardiovascular load. Speak to your GP before you heat the room if any of the following apply. This is not a complete list.
- Heart disease, a recent heart attack or stroke, arrhythmia, unstable or uncontrolled high blood pressure, or known vascular disease
- You faint easily, or you are frail
- You take medicines that affect heart rate, blood pressure, fluid balance, or temperature control
- You are pregnant, or think you might be. NHS-style wording still reproduced on GP practice sites in 2026: there is little research; people may choose to avoid saunas, jacuzzis and steam rooms because of overheating, dehydration and fainting; a significant rise in core temperature could be harmful, particularly in the first 12 weeks.
- You are unsure
Children under three should not be in a hot sauna. Older children need an adult, a cooler bench, and a short stay.
Do not use heat to “push through” chest pain, dizziness you cannot talk down, or a feeling that something is wrong — get out, cool steadily, and get help.
This page is not medical advice. A safety conversation with a clinician is not optional if the list above sounds like you.
What we are not claiming
We are not claiming that sauna prevents heart disease, stroke, or cardiovascular death. We are not claiming that Laukkanen 2015 proves causation. We are not claiming that Mayo 2018 is the original cohort study. We are not claiming that Lee 2022 generalises beyond a small, short trial in people who were also exercising, or that sauna treats high blood pressure. We are not claiming sauna replaces exercise. We are not claiming 100 mm panel insulation is a heart intervention. We are not offering this as treatment.
FAQ
Is sauna good for your heart?
Observational research in middle-aged Finnish men (Laukkanen et al., JAMA Internal Medicine, 2015) found an association between more frequent traditional sauna bathing and lower rates of some fatal cardiovascular outcomes. That is not randomised proof and not a UK sample. Heat is a cardiovascular load. It is not a treatment for heart disease. People with heart conditions should speak to a GP before use.
Does sauna lower blood pressure?
A small eight-week randomised trial (Lee, 2022) found that adding a 15-minute sauna after exercise was associated with a further mean 8.0 mmHg drop in systolic blood pressure compared with exercise alone. That is an adjunct finding, not a hypertension protocol. Do not replace prescribed treatment with heat.
Does sauna replace exercise or count as a cardio session?
No. Heat raises heart rate without the muscle work of training. Lee 2022 put the sauna on top of guideline-based exercise. The walk still has to happen.
Can I use a sauna if I have high blood pressure or heart disease?
Not as a hobby you copy from a reel. Speak to your GP first if you have heart disease, arrhythmia, uncontrolled blood pressure, a recent heart attack or stroke, or you are unsure. Uncontrolled blood pressure and unstable disease are reasons to wait for clinical advice, not reasons to “start gently and see.”
How often should a healthy adult sit in the heat?
Two or three sessions a week is a reasonable habit if you already like it. That is not a medical dose. Four to seven times a week was a group in the Finnish cohort, not a prescription.
Is this medical advice?
No. If you have heart disease, arrhythmia, uncontrolled blood pressure, are pregnant, or are unsure, speak to your GP before you heat the room.
Sources
- Laukkanen 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. https://doi.org/10.1001/jamainternmed.2014.8187
- Laukkanen 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. https://www.mayoclinicproceedings.org/article/S0025-6196(18)30275-1/fulltext — https://doi.org/10.1016/j.mayocp.2018.04.008
- Lee E, Kolunsarka I, Kostensalo J, et al. Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm randomized controlled trial. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 2022. https://doi.org/10.1152/ajpregu.00076.2022
- Massey H, interviewed by Finlay M and Sample I. Revisited: saunas, cold plunges — where does the evidence stand? The Guardian Science Weekly, 30 July 2026 (re-air of 2 April 2026). https://www.theguardian.com/science/audio/2026/jul/30/revisited-saunas-cold-plunges-where-does-evidence-stand-podcast
- Rufo Y. Saunas and cold plunges: what does the science say? BBC News, 30 December 2025. https://www.bbc.com/news/articles/c5yj3g0p26ro
- Collingwood Surgery. https://collingwoodsurgery.nhs.uk/collingwood/common-questions/pregnancyis-it-safe-to-use-a-sauna-or-jacuzzi-if-i-am-pregnant
Byline: Wellness One specialist team, Wellness One Healthstyle Ltd (Co. No. 14514433)
Last updated: 27 August 2026
This page is not medical advice.