THE SHORTENING OF THE PHOTOPERIOD MAY ALTER GENE-EXPRESSION IN WINTERDEPRESSION

Winter depression is characterised by recurrent major depressive episo des with a seasonal (winter) pattern. Reduced exposure to daylight due to shortening of the day has been hypothesized to trigger off the ons et of a depressive episode. Daily exposures to light during the dark p eriod have been used as the treatment of choice for winter depression. A genetic predisposition for high responsiveness to light is thought to exist in patients with winter depression. Altered gene expression m ay contribute to the unique sensitivity and mediate the antidepressant effects of light.