2What is Red Light?
Shine light through a prism and it will fragment into all the colors that makeup the visible spectrum of light, including green, blue, purple, yellow, orange and red. Red light is a form of radiation that’s visible to the human eye, and which we have collectively agreed to call red.
Most wavelengths of light, such as ultraviolet, blue or green light, don’t penetrate the skin deeply at all and are instead absorbed by the surface layers of skin. Conversely, red light easily penetrates skin, which makes it useful therapeutically for reaching cells and tissues deeper inside the body.
The Cell Phone Flashlight Experiment
To witness the unique ability of red light to penetrate deeply into body tissues, here is an interesting experiment you can try which I learned from Finnish health researcher Vladimir Heiskanen in his comprehensive paper on red and infrared light therapy.
Simply take out your mobile phone and load the flashlight application. Next, hold the tip of your finger directly against the light and look at your finger. What do you see? Although your mobile phone flashlight emits blue, green and red light – only the red light penetrates all the way through your finger. Look at the red glow!
Red light ranges in wavelength from about 620-700 nanometers (nm). The following is a diagram of both visible and invisible wavelengths electromagnetic radiation and the colors they create as perceived by the human eye.