Science Behind Infrared & Red Light Therapy
What is Light?
To understand what is infrared light you first need to understand what is light? To keep it basic, light is energy in the form of a wavelength that moves at a certain frequency. The graph above shows the different wavelengths and frequencies and their respective names. To the Human eye, we are only able to see light in a narrow range of wavelengths/frequencies and this is called; the Visible Spectrum. What also is depicted in the graph above, is that there is an inverse relationship (one goes up and the other goes down) of the size of the wavelength and frequency and the corresponding energy that it has
As the length of the wave increases and the frequency that it is moving at decreases, so does the energy that it possesses. It would be like going from a pulled out piece of yarn at the radio wave end of the spectrum- where the wavelength is very looonnngggg and the frequency at which it is moving is very slow. The other end, the Xray and Gamma rays would be like a slinky all wound up tightly- it possesses a lot more energy than the pulled apart string and is moving very fast and the length of the slinky is much shorter.
This makes sense on a practical scale, as Xrays can go through us to create an image and radio waves have a difficult time traveling distances with any object between the origin of the signal and the receiver.
What is Infrared Light?
Infrared light is the spectrum of light that is just outside of the visual spectrum of light and it so happens to be just outside of the light we see as Red. Infrared light was discovered, by accident by the German-British astronomer William Herschel in the 1800. He is famous for discovering the planet Uranus in 1781, but grew curious of how much heat was passed through the different colored filters he would use on his telescope the he used to observe the sun (1).
He directed sunlight that was coming through his window through a prism to separate the light into its various colors. He then placed a thermometer, that he had painted the ends black to better absorb the heat, within each color to measure the heat. He also placed two thermometers on both ends of the spectrum, just outside of the colors as controls. What he did notice was that red had the hottest temperature reading of all the colors and then he began to wonder if the temperature would increase even further just outside of the red visible light. He placed another thermometer just outside of the red light and what he found was astonishing. That the region just outside of the visible red light was the hottest (1). He called this invisible light “Calorific Rays”, coming from the latin word Caloric meaning heat. (1) This is one of the first experiments that helped to prove that there was a spectrum of light and energy that we could not see.
Today infrared light is used in many applications. In medicine it is used to help analyze body composition and different tissues. It is used in space to help study distant plants vegetations and climate Firefighters and Police use infrared cameras to spot people who may be trapped under heavy smoke and they are unable to see them; as the human body puts off infrared light that is invisible to the human eye but can be recorded on special devices. (1)
For over 300 thousand years sunlight has been used in Traditional Chinese Medicine (TCM), Indian Ayurveda medicine, by the Egyptians and Native Americans. (2) Humans have had a beneficial relationship with light and electromagnetic waves and each wavelength has a different benefit. For example, UV-B radiation promotes Vitamin D synthesis in our skin and our circadian rhythm is run off visible light. When we listen to the radio, we are utilizing radio waves, which are at the far end of the spectrum.