“Even ultraviolet light can produce electronic excitation and bystander effects that destabilize cells, but, unlike gamma rays and x-rays, ultraviolet light doesn’t penetrate deeply into the body. In visible light, it is only the red component that can pass deeply into the tissue, and it happens that red light is able to “quench” many excited electrons, restoring them to their normal resting or ground state. In a solid material,such as a seed or hair or bone, excited electrons will persist for a long time (hours in the seed and hair, years in bone), but with a brief exposure to red light, they will return to their normal state. This beneficial effect of the red component of sunlight helps to keep plants from being sunburned. If the red light is removed from sunlight, even the blue light by itself is quickly toxic to their mitochondria.“ -Ray Peat