 Photobiomodulation, PBM, is the use of red and near-infrared light to stimulate healing, relieve pain, and reduce inflammation. The primary chromophores have been identified as cytochrome C oxidase in mitochondria and calcium ion channels, possibly mediated by light absorption biopsins. Secondary effects of photon absorption include increases in ADP, a brief burst of reactive oxygen species, an increase in nitric oxide, and modulation of calcium levels. This article was authored by Michael R. Hamblin.