Seasonal changes in human behavior have been recognized since ancient times. Starting in 1980 systematic research has been carried out by Rosenthal et al. (1984), who described and characterized a psychopathological and clinical syndrome which is linked to fall/winter and shows remission in spring/summer and which was termed seasonal affective disorder (SAD). The symptomatology includes depressed mood, decreased energy, hypersomnia, increased appetite and subsequently weight gain and frequently carbohydrate craving. The efficacy of light therapy with bright, fluorescent, full-spectrum light has been widely demonstrated for treatment of fall/winter SAD. In addition, treatment with selective serotonin reuptake inhibitors appears to be successful in this condition.