For most people, regular sauna use does seem to be good for your health, with the clearest signals pointing to your heart and blood vessels, recovery after training, and plain relaxation. In an episode of The Healthcast, consultant physician Diederik Smit walks through what actually happens in your body when you step into the heat, what the science does and doesn’t tell us, and how often and how long you’d need to go to see a benefit. One thing first: if you have heart or blood pressure problems, are pregnant, or you’re just not sure, check with your doctor before you start using the sauna intensively.
What the sauna does to your body
It feels like pure relaxation, but under the bonnet your body is actually bracing itself. It wants to hold a stable core temperature of around 37C, and the heat of a sauna at roughly 80C is a threat to that.
To shed the heat, your blood vessels widen, you start to sweat, and your heart has to pump harder. Your cardiac output goes up and your sympathetic nervous system kicks in, a kind of mild fight-or-flight mode. As Diederik puts it, you’re essentially putting your body under a lot of stress. It’s a short, controlled dose of stress, more or less comparable to light exercise.
The proven benefits: heart, vessels and brain
The strongest signals come from large observational studies, especially out of Finland and Scandinavia, where thousands of people were followed for up to 20 years.
In people who go often (four to six times a week) versus those who go just once a week, you see sizeable differences: up to 40 to 50 percent less cardiovascular disease, sudden cardiac death and overall mortality, and even a markedly lower chance of dementia.
A word of caution, though. This is not hard proof of cause and effect, because these are not randomised trials. But the effect is large and it turns up in several studies, which is what makes it plausible in Diederik’s view rather than a fluke.
Why it might help your heart and brain
The encouraging part is that there are biological explanations that make the link believable. Blood pressure often sits a little lower in the period after a sauna, and blood pressure is a major driver of cardiovascular disease and dementia.
On top of that, there are hints of better blood vessel function and lower inflammation markers. And because your cardiovascular system has to work harder to cool you down, the effect looks a bit like exercise.
Researchers also point to so-called heat shock proteins, which help your cells clean up and repair, and BDNF, a molecule linked to a healthier brain. None of this is settled, but they’re all plausible mechanisms that could feed into the benefits people have found.
Sauna after training: faster recovery
Here the evidence is a notch firmer, because there is reasonably good randomised research on it. If you spend a short spell in the sauna after a heavy strength session, you tend to recover faster and have less muscle soreness.
Timing matters: do it fairly soon after your workout, roughly within one to two hours. There’s a reason so many gyms have a sauna tucked in the corner.
A nice contrast with the ice bath: an ice bath can blunt your muscle growth after training a little, whereas there are no strong signs of that with the sauna. So for your training results, the sauna is the safer choice.
Does the sauna replace a workout? No
A common question is whether you can swap an easy steady-state session for an hour in the sauna. Not quite. The sauna can support your performance to a degree, but studies show that exercising and using the sauna together beats doing either one on its own.
So treat the sauna as an add-on, not a substitute. For people who can’t exercise properly for medical reasons, it can be a useful way to nudge the heart rate up a bit and give the body a stimulus it wouldn’t otherwise get.
How often and how long for an effect?
The studies are mostly about the dry sauna. The protocol that comes out of them looks like this:
- Frequency: at least four to five times a week. At two or three times you already see some benefit, but most of the gains sit from around four sessions upwards.
- Duration: at least 20 to 30 minutes per session. Ten minutes is really too short.
- Temperature: towards 80C in a dry sauna.
With an infrared or steam sauna the temperature is lower (around 40C as a rough guide) and the data is less clear-cut; the time stays around 20 minutes.
Be realistic about this. Four to five times a week is really only doable if you have a sauna in or very near your home. If you go once a month for the social side of it, enjoy it, but don’t count on a big health payoff. And if you’re weighing up a home sauna, keep in mind it’s a serious purchase (easily hundreds to a few thousand pounds), so it only makes sense if you’ll genuinely use it that often.
The downsides: who should give it a miss?
The sauna isn’t safe for everyone. Diederik flags people who are cardiac-unstable in particular: those with coronary disease, or who’ve had a heart attack, a stent or a bypass, or who get chest pain on exertion. For them, the sauna can be unwise.
Pregnant women are also better off avoiding it, or at the very least keeping it short and not too hot. When in doubt, talk to your doctor.
For men there’s one more thing to keep in mind: frequent, very hot sauna use can temporarily lower sperm quality. The effect is usually small and not permanent, and it recovers when you cut back, but it’s worth knowing if you’re trying for a baby.
Sauna and better sleep
A pleasant bonus is that the sauna may help you sleep. The best window for it is roughly one to two hours before bed, not right before.
It sounds contradictory to climb into a hot room before sleep, but that’s exactly what opens your blood vessels wide. When you step out afterwards, your body cools down very efficiently, and that drop in body temperature helps you drift off more easily.
The evidence here is mostly anecdotal, but it’s plausible. If you often struggle to fall asleep, this can be a handy tool to try.
Frequently asked questions
How often is the sauna good for you?
For a health benefit, the studies point to at least four to five times a week, for at least 20 to 30 minutes in a dry sauna of around 80C. At two or three times a week you already see some benefit, but most of the effect sits from about four sessions upwards. Once a month is mainly relaxing and enjoyable, with probably little impact on your long-term health.
Is the sauna good after exercise?
Yes. Randomised research suggests that a short spell in the sauna soon after a heavy session can mean faster recovery and less muscle soreness. Do it fairly quickly after your workout, roughly within one to two hours. Unlike an ice bath, the sauna doesn’t blunt your muscle growth, so for your training results it’s the safer choice.
Can you lose weight with the sauna?
The sauna puts your cardiovascular system to work and burns a little extra energy, a bit like light exercise. But it’s no substitute for training or a sensible diet, and any weight you see drop straight after a session is mostly fluid you’ll replace by rehydrating. Exercising plus using the sauna does more, according to the science, than either on its own. So don’t rely on the sauna as a slimming aid.
Does the sauna lower your blood pressure?
During a sauna your blood pressure actually rises, but in the period afterwards it often sits a little lower. Because lower blood pressure is an important factor in less cardiovascular disease and dementia, this is seen as one of the beneficial effects. If you have heart or blood pressure problems, check with your doctor before using the sauna intensively.
Which is healthier, sauna or ice bath?
For long-term health benefits, the sauna stands on firmer ground than the ice bath. The evidence for lasting benefits from cold plunges is thin, and an ice bath can even blunt your muscle growth after training. A cold plunge can still help with relaxation and breathing techniques, but if you’re choosing for health, the evidence for the sauna is a notch more convincing.
Is the sauna safe during pregnancy or with heart problems?
Not without care. During pregnancy it’s better to avoid the sauna or at least keep sessions short and not too hot. If you’re cardiac-unstable, for example with coronary disease, after a heart attack, stent or bypass, or with chest pain on exertion, the sauna can be unwise. In both cases, talk to your doctor before going in.
