Stimulation of reactive oxygen species production by an antidepressant visible light source

Background:The mechanism by which visible light stimulates chronobiological phase-shifting or antidepressant effects in humans is unknown. Methods:Normal human NIH/3T3 nonpigmented fibroblasts were irradiated with a visible light source (SunRay) used in the treatment of winter seasonal depression. Electron spin resonance was assessed before and after 10 min of illumination at 2 mW/cm2 (illuminance of 3700 lux), with and without the presence of 5 μL of 0.0214 mg/mL vitamin C. Results:The fibroblasts showed evidence of production of reactive oxygen species after 10 min of irradiation. Conclusions:These in vitro data establish that an antidepressant source of visible light is capable of inducing the production of reactive oxygen species in skin. Such species may participate in signal transduction pathways leading to mood changes.