The colour spectrum, or visible light, is part of the electromagnetic spectrum. The electromagnetic spectrum (EM) is the range of all types of EM radiation.
The electromagnet spectrum is divided into regions dependent on the length of the wavelength and the frequency of the vibrations. Visible light or the colour spectrum has a short wavelength and high frequency. Other regions on the electromagnetic spectrum include radio waves, , infrared waves, ultraviolet waves, e-rays and gamma waves (The Electromagnetic and Visible Spectra). We accept the effect of these invisible waves, such as x-rays on our bodies but the effects of colour or light on the body seems to have fallen into the realm of alternative and therefore unsubstantiated, therapies. Why is that?