Sweating practices have been used throughout the world, to help people gain physical, mental and spiritual health. It promotes positive effects on sleep, mood and on hyperactivity, specifically for people with anorexia nervosa. Examples of different forms of group sweating include the American Indian sweat lodge ceremony, the Finnish sauna, the Russian bania, the Jewish shvitz, the Islamic hammam, the African Sweat Hut, the Mexican Temazcal and the Japanese mushi-buro. References to group sweating have been cited as old Celtic and Teutonic practices, important in tribes of Africa, Melanasia, Australia, New Guinea, Polynesia, and was a central practice to the Greeks, Romans, and Aztecs. Bikram Yoga, which combines group sweating with yoga, is also becoming increasingly popular.
One of the most consistent descriptions is that sweating facilitates relaxation and stress relief. The heat of a sweat bath and the often rapid cooling afterwards, conditions the body. A well-tuned body is more resistant to colds, disease and infection. Depending on how hot the sweat bath is and the climate in which it occurs, a fifteen minute sauna or sweat can perform the heavy metal excretion that normally takes healthy kidneys 24 hours to accomplish. Body sweat flushes toxic metals such as copper, lead, zinc, and mercury from the body. A sweat lodge or sauna is often recommended as a supplement to kidney machines. Sweat can also remove excessive salts; this is generally believed to be beneficial for cases of mild hypertension. Sweat can also eliminate urea, a metabolic by-product. Sweat may also draw out lactic acid responsible for stiff muscles and a contributor to general fatigue. Lungs benefit, too. Clogged respiratory passages are opened by heat; this gives relief from colds or minor respiratory problems.
Finnish tests validate the practice of splashing water on superheated rocks as a means to produce an abundance of negative ions. This seems especially true if the rocks are heated by a wood fire. It is known now that where there are too few negative ions and too many positive ions, have been linked to heart attacks, aggravated asthma, migraines, insomnia, rheumatism, arthritis, hay fever and allergies.
Sweat baths are not recommended for persons with pneumonia and major respiratory problems. Sweating is also contraindicated during high-risk pregnancies and for patients with unstable angina pectoris, recent myocardial infarction, severe aortic stenosis, decompensated heart failure, and cardiac arrhythmia.