People have enjoyed hot baths or saunas for millennia, dating back to the ancient Egyptians, per the Guardian. Bathhouses remain popular in many parts of the world, including South Korea. In Finland, a country of 5.5 million people and 3 million saunas, sauna bathing is known as "the poor man's pharmacy." "All of these cultures ... extol the health benefits of these practices. And we now know they have been right all along," Charles James Steward, a PhD candidate at Coventry University in the UK, writes at the Conversation. Steward and colleagues have been reviewing the effects of "passive heating" on the body, and what they've found is pretty remarkable. Their review of recent studies shows numerous health benefits comparable to those offered by low- to moderate-intensity aerobic exercise, like walking, jogging, and cycling.
One study found sauna use was tied to a decreased risk of fatal cardiovascular disease. Those who bathed in a sauna four to seven times per week actually had a 50% lower risk of fatal CVD than those who did so once per week. There's also research tying sauna use to a decreased risk of dementia, as well as some indications that a hot soak might also improve symptoms of depression. Other benefits include "improvements to cardiorespiratory fitness, vascular health, glycemic control, and chronic low-grade inflammation," per the review. As Steward notes, sitting in a hot bath or sauna increases your body temperature, raises your heart rate, and increases blood flow—just like exercise. Of course, it shouldn't be considered a substitute for exercise, as you won't get any more muscle mass or lose fat. But Steward notes it could benefit sedentary cultures and those who can't exercise for long periods. (Read more health research stories.)