During laser/light therapy, a low-level laser, usually red, is applied to the area of sun-damaged skin. The laser transmits photons about three inches into the skin. Mitochondria in the skin membranes absorb the red laser light, causing an increase of adenosine triphosphate levels, leading to an increase in healthy cell production. The process also promotes healing by increasing production of collagen, enzymes and cell growth. The increased collagen production helps prevent scar tissue from forming.