Just as visible light has a
range of wavelengths (running from
red to violet), so does
infrared light: longer wavelength
infrared waves are thermal, while short or near
infrared waves are not hot at all, in fact, you can not even feel them.
Visible radiation in the
red, orange and yellow color
range emitted by near
infrared saunas appear to stimulate the lower body organs, including the organs of elimination — the liver, kidneys and large intestines — and the adrenal glands, among others.