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An infrared sauna uses infrared heaters to emit infrared light experienced as radiant heat which is absorbed by the surface of the skin. Traditional saunas heat the body primarily by conduction and convection from the heated air and by radiation of the heated surfaces in the sauna room.
Health benefit claims
A study of patients with rheumatoid arthritis and ankylosing spondylitis showed a reduction in pain, stiffness and fatigue during infrared sauna therapy, but since results from the study "did not reach statistical significance"  there is no clear or certain relationship between reducing symptoms and using infrared sauna therapy.
"Toxins" and "toxicity" are general terms used by alternative health professionals and some doctors to cover a wide range of substances from petrochemicals to heavy metals, which are excreted in very small quantities (less than 1%) while sweating. See sweat composition. Proponents of FIR sweating claim a toxin content of up to 15% vs. conventional sweating. Saunas may be useful to those who cannot sweat from exercise due to their health problems.
Only if the sauna uses far-infrared technology, the sauna might be more tolerated by patients who don't tolerate the high temperatures of the standard humid hot air saunas. This is because far-infrared rays do not heat the air inside the sauna, but they still heat the body. However, most infrared saunas in the market do not use the expensive far-infrared panels, which can be touched because they remain always cold, but much cheaper low and medium-infrared heaters, which remain very hot when used and also heat the air of the sauna.
Energy expenditure and weight loss
Some infrared sauna proponents claim that the sauna is an effective method for considerably raising the rate of energy expenditure in the body. Proponents typically quote the Journal of the American Medical Association stating: "A moderately conditioned person can easily sweat off 500 grams in a sauna, consuming nearly 300 kcal, which is equivalent to running 2–3 miles. A heat-conditioned person can easily sweat off 600–800 kcal with no adverse effects. While the weight of the water loss can be regained by drinking water, the calories consumed will not be."
- Sagar Naik (2008-09-21). "Infrared Radiation". Scribd.com. Retrieved 2013-12-12.
- Oosterveld FG, Rasker JJ, Floors M, et al. (January 2009). "Infrared sauna in patients with rheumatoid arthritis and ankylosing spondylitis. A pilot study showed good tolerance, short-term improvement of pain and stiffness, and a trend towards long-term beneficial effects". Clin. Rheumatol. 28 (1): 29–34. doi:10.1007/s10067-008-0977-y. PMID 18685882.
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- Searle AJ (January 1982). "Effects of the sauna". JAMA 247 (1): 28. doi:10.1001/jama.1982.03320260016012. PMID 7053434. – letter