INVOLVEMENT OF MELATONIN AND SEROTONIN IN WINTER DEPRESSION

The phase of circadian rhythms can be shifted by exposure to light. Mo st patients with winter depression are suggested to have a phase delay in their circadian rhythms. The efficacy of light in treatment of win ter depression is thought to be associated with the phase shifting eff ect of light. In addition to light, melatonin and serotonin can cause phase shifts of the rhythms. The concerted action of these indoleamine s may underly the finding that light has an antidepressant effect, ind ependently of time of day or circadian phase of an individual.