Bright Light Therapy in Seasonal Affective Disorder (SAD)

Bright light therapy (BLT) is widely accepted as first-line treatment of seasonal affective disorder (SAD). However, the mechanism of action of BLT is still widely unknown. On the other hand, in mammals, light penetrates the skull bone and reaches the brain, and extra ocular transcranial phototransduction has physiological influences such as changed reproductive cycles and increased brain serotonin levels. Therefore, the investigators run a randomized, placebo controlled, double blind, dose finding study on the putative effect of transcranial bright light in the treatment of SAD.