Sauna might seem like a modern invention but, in truth, it had been around since 1112 A.D. Even then, the concept was the same: stones are heated via fire, then placed inside an enclosed space. These stones, in turn, cause the air inside the enclosed space to get heated as well.
Far Infrared: What It Is
Regardless whether it’s a 2 person infrared sauna or a one person infrared sauna, both make use of far infrared, or FIR, light waves to heat objects without actually warming the air around. While FIR might sound like something straight from a science fiction novel, it is actually more common than you think. In fact, you can feel FIR light waves coming off the palm of your hands, or from a smooth stone after it has been under the sun for so long.
As opposed to a traditional sauna, an infrared sauna makes use of heaters made of coils coated in various materials, including ceramic and carbon. These heaters are installed along the walls of the sauna and emit heat energy which, upon reaching your skin, gives warmth to the tissue. This provides the same effect as a traditional sauna but at a much lower temperature.
You might ask why the air does not get heated in the same way as in a traditional sauna. This is because the infrared heat being emitted by a FIR sauna is similar in wavelength to the ones being emitted by the human body. The waves are able to penetrate the body from where they are able to warm the muscles.