The sauna is one of the oldest wellness habits on earth, and one of the few that has survived contact with modern science largely intact. It is also surrounded by more confident opinions than almost any other recovery tool, most of them about infrared cabins, contrast showers and exact temperatures. This guide cuts through that. It explains what the two main sauna types are, where the research is actually deepest, how to cool down like you mean it, and the details that matter if you are a man trying to conceive or a woman timing heat around your cycle.
Infrared vs traditional: they are not the same thing
A traditional sauna, the Finnish kind, heats the air. A stove warms the room to roughly 80 to 100°C, the air is dry, and you can throw water on hot stones to raise the humidity in bursts. Your body is heated from the outside in, by hot air and steam. This is the version that has been part of Nordic life for centuries.
An infrared sauna works differently. It uses infrared panels to warm your body directly, the way the sun warms your skin on a cold day, while the surrounding air stays much cooler, often 45 to 60°C. Many people find it more tolerable for that reason, and you can sit in it longer before it feels intense.
Both raise your core temperature and make you sweat, which is the point. But here is the honest part most marketing skips: the bulk of the long-term population research, including the well-known Finnish cohort studies, was done on the traditional hot, dry sauna. That is simply where the deepest evidence lives. Infrared is plausible and pleasant, but it does not yet have the same decades of data behind it. If you are choosing, neither is wrong, but only one of them is what the famous studies are actually describing.
| Traditional (Finnish) | Infrared | |
|---|---|---|
| How it heats you | Hot, dry air (and steam) | Infrared panels warm the body directly |
| Typical temperature | ~80-100°C | ~45-60°C |
| Feel | Intense, classic, social | Gentler, easier to tolerate longer |
| Depth of research | Deepest (long Finnish cohorts) | Promising but far less long-term data |
What the long-term Finnish research actually looks at
The most cited sauna evidence comes from the Kuopio Ischaemic Heart Disease study, a long-running Finnish cohort led by cardiologist Jari Laukkanen. Researchers followed more than two thousand middle-aged Finnish men for around twenty years and tracked, among other things, how often they used a traditional sauna. The headline finding was that more frequent sauna use was associated with lower cardiovascular and all-cause mortality, with the strongest associations in the men who used it four to seven times a week compared with once a week.
Two honest caveats matter here. First, this is observational research: it shows an association, not proof that the sauna alone caused the difference. People who sauna often may differ in other ways. Second, and importantly for us, none of this is a claim about any drink or supplement. It is a description of what a body of heat research investigates, nothing more.
Traditional saunas heat the air to around 80 to 100°C; infrared cabins run cooler and warm you directly. Both make you sweat, but the deepest long-term research is on the traditional kind. Use it regularly, cool down with intent, and let your own tolerance set the dose. Men trying to conceive should ease off the frequent hot sessions; women should read their cycle and skip it in pregnancy unless a doctor says otherwise.
Cooling down is part of the protocol, not an afterthought
The contrast is where a lot of the felt benefit lives. After a round in the heat, the traditional move is to cool the body down deliberately: a cool shower, a plunge, a roll in the snow, or simply standing in fresh air until your breathing settles and you stop sweating. Then, if you like, go back in. Most people do two or three rounds. The cool-down is not a way to end the session early; it is the rhythm of the whole thing. If you want to pair heat with cold deliberately, our separate cold plunge guide covers how to do the cold half safely.
For men: cool down properly, and the honest bit about fertility
Here is the part the recovery crowd has finally started talking about, and it is worth understanding rather than burying. Your testicles sit slightly cooler than the rest of your body on purpose, because sperm production is heat-sensitive. So regular, frequent sauna use can temporarily lower sperm count and quality. Studies that had healthy men use a hot sauna regularly for a few months measured real drops in sperm count and movement. The reassuring half of that finding is that the numbers returned to normal within a few months of stopping. It is a temporary, reversible effect, not damage.
The takeaway is not "never sauna." It is this: if you and your partner are actively trying to conceive, treat frequent hot sessions as something you can pause, and ease off or skip them until you are through that window. Your future kids will not mind the break.
The rest of the time, the cooling trick men talk about is just good thermoregulation done on purpose. Do not walk out of a hot cabin and sit around in warm clothes letting the heat linger. Cool the whole body down after each round: a cool or cold shower, or a plunge, brings your core temperature back down and the lower body with it. Some men make a point of finishing on cold before they dress. The principle is simple, heat up deliberately, then cool down deliberately, and do not let heat sit where it is not wanted.
For women: cycle, pregnancy, skin and iron
Your cycle changes how heat feels. Many women notice their comfort in the sauna shifts across the month, with core temperature naturally running a little higher in the luteal phase (the roughly two weeks before a period). A hot, long session can feel more taxing then. There is no fixed rule: let how you feel set the length and intensity rather than forcing a protocol, and ease off when the heat feels harder than usual.
Pregnancy is a caution, not a maybe. The standard guidance is to avoid or strictly limit very hot, long sessions during pregnancy, especially in the early months, because overheating is something clinicians actively advise against. If you are pregnant or think you might be, check with your doctor or midwife before any sauna use and follow their call over anything you read here.
The skin and circulation angle is real. Plenty of women use the heat-then-cool rhythm as a circulation ritual: the heat opens things up, the cool-down brings tone back, and the whole cycle gets blood and lymph moving. Nothing miraculous, just your circulation doing its job, and your skin looking a little more awake afterwards.
Mind your iron and your hydration. Heavy sweating costs you fluid and some electrolytes, so drink water around a session. And if you run low on iron, which is more common for women, big heat sessions can leave you more wiped out or lightheaded than expected. On the days you feel that, go gentler.
The Bryan Johnson take, and why it is just an enthusiast's version
Bryan Johnson, the founder who turned his own longevity routine into a public project, is often quoted on sauna. His approach is unglamorous and worth noting precisely because it is not exotic: a hot, dry sauna around 90°C for roughly twenty minutes, several times a week. That is essentially the same protocol the Finnish population studies describe, done consistently by someone who measures everything. The lesson is not that you need his budget. It is that the version with the most evidence behind it is also the most ordinary one.
A sensible starting protocol
- Frequency over heroics. Regular, moderate sessions beat occasional extreme ones. Two to four times a week is a reasonable place to start.
- Time, not torture. Ten to twenty minutes per round in a traditional sauna; longer is fine in a cooler infrared cabin. Come out before you feel unwell, not after.
- Hydrate. You lose real fluid sweating. Drink water before and after.
- Cool down between rounds. A cool shower or fresh air, then back in if you want a second or third round.
- Wear a wool hat if you do hot, dry heat often. The air at head height is the hottest in the room, so a felted wool hat shields your hair and scalp and lets you stay comfortable longer. Cheap, slightly absurd, and worth it.
- Listen to your body and skip it if you feel faint, are unwell, have a heart condition, or are pregnant without your doctor's go-ahead.
The sauna is a genuinely old, genuinely studied habit. Traditional hot-dry cabins have the deepest research; infrared is gentler but less proven. Go regularly rather than dramatically, and cool down on purpose. Men: the sperm-count dip from frequent heat is real but temporary, so pause it when you are trying to conceive. Women: read your cycle, and treat pregnancy as a talk-to-your-doctor moment. None of this is a health claim, and none of it is about what any drink does for you.
References
- Laukkanen, T., Khan, H., Zaccardi, F., & Laukkanen, J. A. (2015). Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine, 175(4), 542-548.
- Laukkanen, J. A., Laukkanen, T., & Kunutsor, S. K. (2018). Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings, 93(8), 1111-1121.
- Kunutsor, S. K., Laukkanen, T., & Laukkanen, J. A. (2018). Sauna bathing reduces the risk of respiratory diseases: a long-term prospective cohort study. European Journal of Epidemiology, 33(3), 351-353.
This article is for educational purposes and is not medical advice. Heat exposure is not suitable for everyone. If you are pregnant or breastfeeding, have a heart condition or low blood pressure, or take prescription medication, talk to your doctor before sauna use. Daylight is a food supplement and nothing in this article is a claim about what it does.
