why you sleep so well after a sauna, and how to make the most of it

Of everything people tell us when they come back for a second visit, one thing comes up more than any other. Not their skin, not their muscles. They say they slept.

It is worth being careful about why. The mechanism is reasonably well understood, the research on warming the body before bed is decent, and the research on saunas specifically is thinner than most sauna marketing would have you believe. Here is what we think is going on, and how to use it.

what happens to your body before sleep

Your core body temperature is not fixed. It drifts through the day and falls in the evening, and that fall is one of the signals your body uses to start winding down for sleep. To cool the core, blood is moved out towards the skin, the hands and the feet, where heat can escape.

Heat speeds that process up. When you sit in a sauna, your body pushes blood to the surface to get rid of heat. When you step out, that redirected blood keeps shedding heat, and your core temperature drops faster than it would on its own. Arriving at bedtime with a core that is already cooling is, in short, what your body was trying to do anyway.

what the research says

The strongest evidence is not about saunas. It is about warm baths and showers, which do the same basic thing.

A 2019 review in Sleep Medicine Reviews by Haghayegh and colleagues pooled the studies on what they called passive body heating before bed. Water at around 40 to 42.5°C, taken one to two hours before bedtime, shortened the time it took people to fall asleep, and sessions as short as ten minutes made a measurable difference. The authors put it down to exactly the temperature shift described above.

The sauna research is mostly surveys. The Global Sauna Survey, published by Hussain, Greaves and Cohen in 2019, asked 482 regular sauna users about their experience, and 83.5% said sauna use improved their sleep. That is a striking number, but it is self-reported, from people who chose to answer a survey about something they already enjoy, so it cannot show that the sauna caused the better sleep.

Our read is that the mechanism is real, the bath research supports it, and most of our guests report the same thing. What nobody has shown yet is a controlled trial of infrared saunas and sleep, so we would not promise it.

There is also the simpler part. An hour in a private room, phone away, nobody needing anything from you, is not nothing. A lot of people sleep badly because they never really stop. This is a place where you do.

the cold plunge is a different story

Cold water wakes you up. The first fifteen seconds in 7°C water produce a sharp, alert, slightly elated feeling, and plenty of people find it lasts a while afterwards. That is excellent at eight in the morning and less obviously what you want at nine at night.

The evidence here is mixed rather than alarming. One small study, by Robey and colleagues in 2013, had eleven trained cyclists sit in cold water after evening exercise and found it did not change how well they slept through the night. So an evening plunge is unlikely to ruin your sleep. But if sleep is the point of the visit, we would not end on it.

The simple rule is the one we give in our guide to contrast therapy: finish warm. Do your rounds of heat and cold, then make the last one heat, or follow your final plunge with a warm shower and a few quiet minutes before you dress.

how to time an evening session

The bath research points to finishing one to two hours before you plan to sleep, which happens to suit an evening visit well. We are open until 10pm, and the last 60-minute session starts at 9pm.

• Book a slot that ends one to two hours before bed. For most people that means arriving somewhere between 6 and 8pm.
• Sixty minutes is plenty. Two rounds of 15 to 20 minutes of heat with short plunges in between, if you want them.
• Finish warm. Last round in the sauna, or a warm shower after your final plunge.
• Drink water. You will have sweated more than you think. Skip the alcohol, which undoes a good deal of the effect.
• Keep the rest of the evening quiet. A light dinner, low light, not much screen. The session does some of the work; the next two hours do the rest.

who should be careful

If you are pregnant, have a heart condition, have low or high blood pressure, or take medication that affects how you handle heat, including some sleep and blood pressure medicines, talk to your doctor before booking. And if your sleep has been poor for a long time, please see someone about it. A sauna is a nice way to end a day, not a treatment for insomnia. This is general information rather than medical advice.

why a private room helps

Sleep is about winding down, and that is hard to do in a busy gym sauna with people coming and going. Every suite here is yours for the whole session: the infrared sauna, the cold plunge, the hot rain shower and the changing area, behind one door. You can set the lighting low, play something slow on the bluetooth speaker, and leave the cold out entirely if you like.

Sessions are priced per person: THB 1,200 for 60 minutes and THB 1,600 for 90. On a first visit, the code FIRSTTIME20 takes 20% off at checkout. If an evening session becomes part of your week, the monthly memberships start at THB 1,920 for two sessions a month. Everything is on pricing and packages.

Evenings are one of our busier times, so we recommend booking ahead.

questions about sauna and sleep