The role of bright light therapy in managing insomnia

Two types of insomnia, sleep-onset insomnia and early-morning-awakening insomnia, have been associated with delayed and advanced circadian rhythms, respectively. These circadian rhythm abnomalies can be treated with morning bright light in the case of sleep-onset insomnia, and evening bright light in the case of early-morning-awakening insomnia. Although robust evidence shows that appropriately timed light therapy can retime the body clock, evidence of the therapeutic value of bright light therapy for these types of insomnia needs further development. Large randomized controlled trials bright light and behavior therapies, alone and in combination, are needed to improve the treatment of these debilitating disorders.