Experts say that hot steam in a closed room at the end of a harrowing day may be your idea of relaxation, but taking too much sauna may be lethal.
Taking reasonably hot saunas is safe in moderation, but evidence is slim that there are any health benefits besides relaxation.
The issue came upfront when a man died in this year's World Sauna Championships in Finland.
The incident also sparked questions about what even moderate sauna use might do to our bodies.
"A sauna is like a glass of wine: It's probably safe if used in moderation and in an intelligent fashion," Discovery News quoted Thomas Allison, an exercise physiologist at the Mayo Clinic in Rochester, as saying.
In Finland, the practice is a way of life that begins at birth, said Kalevi Ruuska, a native Finn who is president of the North American Sauna Society in Fishkill, N.Y.
"The sauna is almost like a holy thing in Finland. You don't mess with that," Ruuska said.
After too much time in an overly hot sauna, the body might lose too many fluids, which would hinder the skin's ability to sweat and the heart's ability to keep up with demand.
As the air grows more humid, sweat stops evaporating, eliminating its ability to cool Water in the air would have conducted heat, as well, making the air feel even hotter.
Combined with the drop in blood pressure, dehydration and severe heat exhaustion usually cause fainting, which in a sauna can lead to serious burns when the skin comes in contact with searing surfaces. Heart attacks can ensue.
People also occasionally die in commercial saunas, especially when alcohol is involved, people are basking alone, or saunas are poorly made and unventilated, said Richard Livingston, a psychiatrist at the University of Arkansas for Medical Sciences, who has studied the health effects of sweat lodges.
Avoid saunas if you are very old or young, pregnant, have a history of heat intolerance, or have any kind of condition that might affect your heart, including diabetes.
Livingston added, "Doing it to point where you can't do it anymore as an endurance test, just doesn't seem like all that great an idea to me."