Effect of 670-nm Light-emitting Diode Light on Neuronal Cultures

Light close to and within the near infrared range has documented benefits for promoting wound healing in human and animal studies (Conlan et al., 1996; Yu et al., 1997; Sommer et al., 2001). Our preliminary results using light-emitting diodes (LEDs)in this range have also demonstrated twoto five-fold increases in growth-phase-specific DNA synthesis in normal fibroblasts, muscle cells, osteoblasts, and mucosal epithelial cells in tissue cultures (Whelan et al., 2001). However, the mechanisms of action of such light on cells are poorly understood.