Low level laser therapy (LLLT) is a light source treatment with a single coherent wavelength. It consists of a laser of lower power (< 500mw) compared surgical lasers. Unlike cosmetic lasers, LLLT emits no heat, sound, or vibration. Instead of producing a thermal effect, LLLT acts via nonthermal (hence referred to as cold laser) or photochemical reactions in the cells, which is why LLLT is also referred to as photobiology or biostimulation.