Treating Seasonal Depression With Daylight

A seasonal pattern in the on- and offset of depressive episodes in recurrent depressive disorder is prevalent at latitudes with large summer-winter differences in daylength. In Denmark we estimate that 10-12% of the population experience winter depression symptoms with functional impairment, and 1-2% of the population is expected to fulfil the ICD-11 criteria for a recurrent depression episode with a winter seasonal pattern (seasonal depression). First-line treatment of seasonal depression is light delivered by a light box with exposure for ½-1 hour each morning in the season. Based on the physical characteristics and physiological responses daylight should be just as effective as light from a light box. Therefore, in this study the aim is to investigate whether 30 minutes daily outside walks for 6 weeks has an antidepressant effect.