Total or partial sleep deprivation in the second half of the night and phase advance of the sleep-wake cycle have shown to have rapid and profound effects on depressed mood in all diagnostic subgroups. Sleep deprivation attains an immediate response in around 60% of the cases and smaller reported studies using combinations of sleep deprivation with lithium, antidepressant drugs, pindolol, sleep phase advance, or morning light therapy have indicated that the response after initial sleep deprivation can be maintained. Light treatment has become an accepted and effective treatment of seasonal affective disorder (SAD), and recent studies have document accelerated and augmented response in non-seasonal, and even in chronic depression,as adjunctive treatment to medication.