Do Sauna Hats Actually Work? What Heat, Wool and Research Say

In a Finnish sauna, the recommended air temperature of 176 to 212°F (80 to 100°C) is measured at the level of your head, not your feet. That detail comes from a 2018 review in Mayo Clinic Proceedings, and it explains why so many regulars pull on a wool hat before the first round. Here is what a sauna hat can do, what the wool adds, and where the evidence simply runs out.

Key takeaways

1. Your head sits in the hottest layer of air.
2. The head is very sensitive to warmth.
3. Wool works as a buffer between you and the hot air.
4. Steam makes the top of the cabin hotter still.
5. Research on sauna hats themselves is thin.
6. A hat is a comfort tool, and that is how ours started.

1. Your head sits in the hottest layer of air

Hot air is lighter than cool air, so it rises and collects under the ceiling. In their 2018 review in Mayo Clinic Proceedings, Laukkanen, Laukkanen and Kunutsor describe the recommended temperature as 176 to 212°F (80 to 100°C) at the level of the bather's head, and note that it is lower at floor level, which helps ventilation. A Finnish research team (Saari and colleagues, Indoor Air conference, 2002) took its air measurements at the head height of seated bathers and found that even the wooden benches reached around 140 to 158°F (60 to 70°C). The German health magazine Apotheken Umschau sums up the practical result: sit upright and you get cold feet and a hot head, which is why lying down is often recommended. On the top bench, your scalp and ears are the closest part of you to the ceiling.

2. The head is very sensitive to warmth

It is not only that the head gets the hottest air. It also seems to notice heat more than other parts of the body. In a 2014 study in the European Journal of Applied Physiology, Gerrett and colleagues placed a warm probe at 104°F (40°C) on 31 spots of the body in 24 adults (12 men, 12 women) and asked them to rate how warm it felt. Warmth sensation was strongest at the head, then the torso, and it declined toward the hands and feet. The limits are clear: this happened in a room at a comfortable temperature, with a small probe for 10 seconds, not in a sauna. Still, it fits what many people describe. The moment a round starts to feel too much is often the moment the ears and scalp start to burn, long before the rest of the body wants to leave.

3. Wool works as a buffer between you and the hot air

The idea behind a sauna hat is simple: put a layer of insulating material between your scalp and the hottest air in the room. Wool is a good fit for that job. According to the Woolmark Company, wool can absorb up to 35 percent of its own weight in moisture before it feels wet, so a hat soaks up sweat and steam without turning soggy right away. Woolmark also lists the ignition temperature of wool at 1,058 to 1,112°F (570 to 600°C), compared with 491°F (255°C) for cotton. Our hats are made of boiled wool, a wool fabric that is shrunk and compacted with moisture, heat and friction. Britannica describes this process, called fulling, as shrinking the fabric by 10 to 25 percent, which leaves it dense and warm. A dense layer slows down how fast heat reaches what is underneath, the same way a wool sweater slows down the cold.

4. Steam makes the top of the cabin hotter still

In a dry Finnish sauna the relative humidity usually sits between 10 and 20 percent, according to the Mayo Clinic Proceedings review. When someone ladles water on the hot rocks, temperature and humidity rise for a while. Finns call that wave of steam löyly. In German saunas, a sauna master often turns it into a whole ceremony called Aufguss, which we explain in What is Aufguss? Steam rises like hot air, so the wave reaches the top of the room first, right where your head is. Many people find this is when a hat feels most useful, especially over the ears. The frihed. Original covers the ears. The Pro adds extended ear protection and a sewn brim that sits over the forehead and eyes, which is why we suggest it for very hot rounds on the top bench.

5. Research on sauna hats themselves is thin

Here is the honest part. We could not find a peer reviewed study that measured scalp or head temperature in a sauna with and without a hat. So there is no data showing that a hat lowers your body temperature or has any effect on headaches, heat illness or your hair. What research does say is that sauna bathing is generally well tolerated by healthy adults. Hannuksela and Ellahham reached that conclusion in their 2001 review in the American Journal of Medicine, and they also warned that alcohol during sauna bathing raises the risk of low blood pressure, irregular heartbeat and sudden death. A hat changes none of the basics:

• Keep rounds short. The 2018 review describes typical rounds of 5 to 20 minutes.
• Drink water between rounds and skip alcohol.
• Leave the sauna as soon as you feel dizzy or unwell, hat or no hat.

6. A hat is a comfort tool, and that is how ours started

Our founder, Florian Meyer, did not start with a business plan. He sewed himself a hat because his head got too hot in the sauna, and that hat became frihed., which is Danish for freedom. Today the hats are designed in Lüneburg, Germany, and sewn in the workshop of Lebenshilfe Lüneburg, where people with disabilities work. The design is registered, and the Hamburg newspaper Hamburger Abendblatt has featured the brand. There are two versions. The Original is a single layer of boiled wool, fits heads up to 26 in (66 cm) and adapts to your head when you fold the brim up twice. The Pro has a double layer and a roomier cut for heads from 26.4 in (67 cm), lots of hair or dreadlocks. Wear one if it makes your rounds more comfortable. That is the whole point.

FAQ

Do sauna hats actually work?

A wool hat puts an insulating layer between your head and the hottest air in the cabin, and many people find their rounds more comfortable with one. What studies have not shown is any health effect of wearing one.

Why do people wear wool hats in a hot sauna?

It sounds backwards, but the hat is not there to keep you warm. Wool insulates in both directions, so it slows down how quickly the hot air reaches your scalp and ears. It also absorbs a lot of moisture before it feels wet.

Is a wool hat safe in a sauna?

Wool handles sauna heat well and, according to the Woolmark Company, only ignites at 1,058 to 1,112°F (570 to 600°C). Still, never hang a hat on or over the heater, and take it off whenever it feels too warm.

This article is for general information and is not medical advice. If you have a medical condition, are pregnant or feel unwell, talk to your doctor before using a sauna.

Find the right fit among all our sauna hats. Ready for your first round? Read How to wear a sauna hat.