Photobiomodulation refers to the use of photons at a non-thermal irradiance to alter biological activity. Light therapy involves exposing cells or tissue to low-levels of red and near infrared (NIR) light. This process is referred to as ‘low-level’ because the energy or power densities employed are low compared to other forms of laser therapy such as ablation, cutting, and thermally coagulating tissue.

Mitochondria serve as our cellular “power plants”. They convert food molecules to energy (ATP) and oxygen by a process called oxidative phosphorylation. Cytochrome c Oxidase (COX) is the primary photoreceptor for wave lengths of Light Therapy, Nitric oxide in mitochondria can bind to COX and displace oxygen in injured and hypoxic cells. Consequently, a cascade of events occurs in the mitochondria, leading to biostimulation of various processes, thus, Light Therapy can photo dissociate NO from COX and reverse this, when this happens it allows for healing of injured cells to take place.

Light Therapy’s effect on vasodilation was described in 1968. Light Therapy increases blood flow to expedite healing of tissue. It is clinically reasoned that Light Therapy is able to produce a shift for greater cellular oxidation due to the activation of various transcription factors. The most important of these molecules is reported to be ATP, cyclic-AMP and NO. Light Therapy has been clinically shown to enhance cellular proliferation of fibroblasts, endothelial cells and lymphocytes. The proposed mechanism of proliferation is stimulation of mitochondrial cells to activate signal pathways to upregulate transcription factors to increase production of growth factors. Furthermore, Light Therapy also increases neovascularization and collagen synthesis to aid in healing of acute and chronic wounds and soft tissue injuries.