Light therapy or LASER (light amplification by stimulated emission of radiation) is used for pain management, stimulating tissue healing and controlling inflammation. It is used to increase the speed, quality and strength of tissue repair. The effects of pain relief are due to the result of enhanced endorphin release. It is also known as phototherapy and low level laser therapy. The application of low power light causes bio-photons to travel to the damaged cells. This physiologically accelerates cell division by mitochondrial stimulation, increased leukocyte phagocytosis, and fibroblast and ATP production. The release of nitric oxide causes vasodilation and acts as a neurotransmitter, normalizing conductivity and releasing beta-endorphins. There are four classes based on their power. Most therapeutic or cold lasers are Class III (power ranging from one milliwatt to 500 milliwatts). Hot lasers (usually used in surgery) are Class IV (> 500 milliwatts of power). Laser therapy is measured in joules (energy delivered by one watt of laser energy in one second). Most therapies call for one to eight joules of energy. The laser’s wavelength determines the depth of penetration and the higher power simply delivers the energy to the same depth faster.