I frequently get asked a question if an infrared sauna is going to tan a user’s skin like a tanning bed. More specifically, does an infrared sauna produce UV rays that will burn your skin?
Question: Why can we feel infrared light but not ultraviolet rays?
Answer: Do you mean why can you feel infrared light as radiant heat and ultraviolet doesn’t have an ‘immediate’ effect of heat?
This question can be answered by saying that how your body feels the infrared light waves and UV rays as heat has everything to do with how different wavelengths are absorbed by the body. Infrared is a longer wavelength of light which happens to be at the “right” wavelength to activate your body’s vibrational modes in the molecules of your cells which then raise their temperature. The temperature of your cells rise because the overall temperature is just the average vibrational energy of an aggregate of molecules. This is why an infrared sauna raises your core body temperature on the whole.
Ultraviolet on the other hand is much shorter wavelength of light and doesn’t cause your body’s molecules to vibrate. You only feel it much later with a sunburn, which is the result of destructive excitation from UV radiation on your skin.
If you see the light chart above you’ll see that the wavelengths are shorter on the left and get longer on the right. Every other wavelength of light is not absorbed as heat in your cells; which is why infrared is used in saunas and is the type of heat that you feel from the sun! Your body is actually finely tuned to absorb just the right length of light to raise its core temperature. It’s infrared! Which you can’t see, but your body feels as heat. I hope this helps answer your question that you aren’t sitting in a tanning bed while taking an infrared sauna!