Radiant heat is simply a form of energy that heats objects directly through a process called conversion without having to heat the air between. Radiant heat is also called infrared energy or IR. The electromagnetic spectrum is divided into three segments by wavelength, measured in microns or micrometers (a micron = 1/1,000,000 of a meter): 0.076 to 1.5 microns = near or close; 1.5 to 5.6 = middle or intermediate; 5.6 to 1000 = far or long wave infrared. The far infrared segment of the electromagnetic spectrum occurs just below, or "infra" to, red light as the next lowest energy band. This band of light is not visible to human eyes but can be seen by special cameras that translate infrared into visible colors. We can, however, feel this type of light, which we perceive as heat. The sun produces most of its energy in the infrared segment of the spectrum. Our atmosphere has a "window" in it that allows infrared rays -- in the 7 to 14 micron ranges -- to safely reach the earth's surface. When warmed, the earth radiates infrared rays in the 7 to 14 micron bands with its peak output at 10 microns.
The infrared heat produced by infrared saunas is similar to the heat from the sun
.
Our tissues normally produce infrared energy and burn it as fuel to keep us warm and use it for tissue repair. Tissue production of infrared energy is associated with a variety of healing responses. At times, the infrared energy in our tissues may require a boost to a higher level to insure the fullest healing possible for tissue repair. Dr. Tsu-Tsair Oliver Chi, when summing up how infrared devices are attuned to the human body, reported that body tissues that need an infrared boost selectively absorb infrared rays. After boosting a tissue's infrared energy, the remaining rays pass onward harmlessly. This phenomenon is called "resonant absorption." Our bodies radiate infrared energy through the skin at 3 to 50 microns, with most output at 9.4 microns. Our palms emit infrared energy too, between 8 to 14 microns. Palm healing, an ancient tradition in China, has used the healing properties of infrared rays for 3,000 years. Yogis in India also employ palm healing and recommend it especially for relieving eye strain.
