One of the most well studied mechanisms of action of PBM centers around cytochrome c oxidase (CCO), which is in complex IV of the mitochondrial respiratory chain, responsible for the final reduction of oxygen to water using the electrons generated from glucose metabolism. The theory is that CCO enzyme activity may be inhibited by nitric oxide (NO). This inhibitory NO can be dissociated by photons of light that are absorbed by CCO. These absorption peaks are mainly in the red (600–700 nm) and near-infrared (760–940 nm) spectral regions. When NO is dissociated, the mitochondrial membrane potential is increased, more oxygen is consumed, more glucose is metabolized, and more ATP is produced by the mitochondria. Adenosine Triphosphate (ATP) is the main cellular currency of energy in the cell and body.
Another mechanism associated with promoting physiological change through PBM is light-sensitive ion channels that can be activated allowing calcium to enter the cell. After the initial photon absorption events, numerous signaling pathways are activated via reactive oxygen species, cyclic AMP, NO, and Ca2+, leading to activation of transcription factors. These transcription factors can lead to increased expression of genes related to protein synthesis, cell migration and proliferation, anti-inflammatory signaling, anti-apoptotic proteins, and antioxidant enzymes.