A sauna is a small room or building designed to be extremely hot, where people sit to sweat and relax. Traditional saunas, which come from Finland, use heated rocks or wood-burning stoves to warm the air to temperatures between 150 and 195 degrees Fahrenheit. Some saunas create steam by pouring water over hot rocks, while others stay dry.

People have used saunas for thousands of years to cleanse their bodies, soothe sore muscles, and simply feel good. After playing hard outside or finishing a tough workout, sitting in a sauna helps your body relax as the heat makes you sweat out tension. In Finland and other Nordic countries, families often have saunas in their homes and use them several times a week, sometimes followed by a cold plunge or a roll in the snow.

The intense heat might sound uncomfortable, but most people find it calming once they get used to it. Sessions typically last 10 to 20 minutes, and the experience leaves you feeling refreshed and loose. Modern gyms and spas often include saunas, though they’re milder than traditional Finnish versions.