An infrared sauna, or far-infrared sauna, uses infrared light to create heat. Also known as infrared therapy, the infrared lamps heat the body from within, meaning that your body will be directly heated by the light waves penetrating your skin. Think of it like when you walk outside on a sunny day and the sun warms your skin. Four Person Red Cedar Far Infrared Sauna work similarly to warm your body, reaching your muscles and nerves, and are completely safe to use.