The science of sauna
Why is sauna good for you?
A sauna feels good. But there's quite a bit more happening than simply getting hot and having a sweat.
Below, we go through how heat affects your heart and circulation, how the body adapts to regular heat exposure, what it does for exercise recovery, and the genuinely striking, if not fully explained, research around brain health. We've also put together a proper comparison between traditional and far infrared sauna, since they're different experiences and neither one is simply better.
None of this is medical advice, and sauna isn't right for everyone in every situation. We've covered safety properly further down the page. Read it first if you have any health conditions or concerns before you get started.
The details
What's actually going on
We usually think of stress as something to avoid. Physiologically, though, the right amount of stress can be useful. Exercise is stress. Cold is stress. Heat is stress.
When the dose is manageable and there's time to recover, the body responds by activating systems designed to protect itself and maintain balance. Researchers sometimes describe this as hormesis, a relatively small challenge that stimulates an adaptive response. In simple terms: the body gets better at dealing with the heat you're exposing it to.
The other half of the story is what happens when the heat stops. During a sauna your heart rate climbs and the body actively tries to cool itself. Afterwards, as you cool down, the nervous system begins shifting back towards recovery, research measuring heart-rate variability following sauna has found increased parasympathetic activity, the part of the autonomic nervous system associated with rest and recovery.
Then there's the part that's much harder to measure: you sit down, you stop doing things, and your phone can stay outside. For a lot of people, regular sauna becomes one of the few deliberate periods of the day where nothing is required of them. That's a pretty valuable benefit by itself.
The real question
Traditional or far infrared?
They have different strengths and different experiences. Neither one wins outright.
Traditional sauna
The classic, high-heat room
Traditional sauna primarily heats the surrounding air, timber, stones and other surfaces. The temperature is considerably higher, commonly somewhere around 70–100°C depending on preference and setup. Water poured over the stones creates löyly, temporarily increasing humidity and the perceived intensity of the heat.
Traditional sauna generally produces a stronger whole-body thermal and cardiovascular challenge under comparable session conditions. It's also the type behind most of the large Finnish long-term studies, covering cardiovascular health, cardiovascular and all-cause mortality, stroke, dementia, Alzheimer's disease and high blood pressure.
Traditional sauna may suit someone who:
- Loves a genuinely hot sauna.
- Wants the classic sauna experience and löyly.
- Is particularly interested in heat acclimation.
- Wants the sauna type behind most long-term population research.
- Enjoys shorter, hotter sessions.
- Wants an outdoor sauna or a larger communal experience.
Far infrared sauna
Radiant heat, lower air temperature
Far infrared works differently. Rather than relying primarily on extremely hot surrounding air, infrared panels emit radiant energy that's absorbed and converted into heat. That lets an infrared sauna run at a considerably lower air temperature.
Newer human research has demonstrated measurable increases in skeletal muscle temperature during far-infrared sauna use, at real depth, not just at the skin. There's also a growing body of research around exercise recovery, muscle soreness, neuromuscular recovery, pain and some cardiovascular applications.
Far infrared may suit someone who:
- Prefers a lower surrounding air temperature.
- Finds traditional high heat uncomfortable.
- Is particularly interested in training and recovery.
- Likes longer, gentler sessions.
- Wants a convenient indoor home sauna.
- Wants something easy to turn on and use often.
So which is better? There isn't one winner.
If your priority is the classic high-temperature sauna experience, a strong whole-body heat challenge and the type of sauna behind most of the major long-term research, traditional sauna has the advantage. If you prefer radiant heating at a lower air temperature, particularly for convenient home use, relaxation and muscle recovery, far infrared is an excellent option.
And there's another factor that's probably more important than arguing over which technology wins on paper: which one are you actually going to use? A sauna used several times a week is a lot more useful than the theoretically perfect sauna you don't enjoy sitting in.
Want both?
The hybrid option
Because a lot of people can't decide, our Babel Hybrid combines a full-size Harvia heater with infrared panels in the one outdoor cabin. You choose a traditional session with heated stones, or a direct-heat infrared session, in the same sauna. It's not both heating systems running together; it's one cabin that gives you the choice each time you use it.
Explore the Babel HybridPlease read
Sauna safety & medical disclaimer
Sauna bathing is generally safe and enjoyable for most healthy adults, but it isn't suitable for everyone or for every situation. The information on this page is general in nature and isn't a substitute for professional medical advice. If you have a medical condition, are pregnant, or are unsure whether sauna is right for you, speak with your doctor before you start.
Before using a sauna
Check with your doctor first if you have, or have a history of, any of the following:
- Heart disease, high or low blood pressure, or any other cardiovascular condition
- A recent heart attack, stroke, or heart surgery
- Epilepsy or a seizure disorder
- Diabetes, particularly if it affects your circulation or ability to sense heat
- Kidney disease
- Respiratory conditions such as severe asthma
- Any condition affecting your ability to sweat or regulate body temperature
- You are taking medication that affects blood pressure, heart rate, or your ability to sweat
- Any other chronic illness or condition you're unsure about
Pregnancy
If you're pregnant, speak with your doctor before using a sauna. Many doctors advise avoiding sauna during pregnancy, particularly in the first trimester, due to the risk of overheating.
Children
Children should only use a sauna with adult supervision, at lower temperatures and for shorter sessions than an adult would use. If in doubt, check with your doctor first.
Alcohol and recreational drugs
Never use a sauna after drinking alcohol or taking recreational drugs. Both affect your body's ability to regulate temperature and can increase the risk of dehydration, dangerously low blood pressure, and losing consciousness.
Illness, fever and dehydration
Don't use a sauna if you:
- Have a fever
- Are unwell, particularly with an infection
- Are dehydrated
- Have been vomiting or have diarrhoea
- Are feeling faint, dizzy, or unusually fatigued
- Have recently exercised to exhaustion
During your sauna
Get out and cool down immediately if you experience any of the following:
- Dizziness or light-headedness
- Nausea
- Headache
- Rapid or irregular heartbeat
- Chest pain or tightness
- Shortness of breath
- Excessive sweating that suddenly stops
- Confusion or disorientation
- Muscle cramps
- Any sense that something isn't right
Never fall asleep in a sauna.
Cooling down
Cool down gradually after your session and rehydrate with water. If you choose to cold plunge or take a cold shower afterwards, ease into it rather than shocking your system, particularly if you have any cardiovascular condition.
Listen to your body
You know your body better than any general guideline can. If something feels wrong, get out. Sauna should be an enjoyable part of your routine, not an endurance test.
Ready when you are