DEVELOPMENT OF WINTER DEPRESSION AND THE EFFECT OF LIGHT THERAPY

The development and progression of winter depression and the effect of light therapy was assessed in 31 of 83 subjects who reached a Beck Depression Inventory (BDI) score of 15 (indicating severe depression) and were consequently given light therapy. The subjects were regularly evaluated with the BDI at 2-week intervals during the months before and after light therapy. The BDI score increased rapidly during the 4 weeks before treatment and fell immediately after treatment. A marked decrease in depression score was also seen with the Hamilton Depression Rating Scale (HDRS) and HDRS/SAD extension rating scale. Although light therapy had a beneficial effect in most of our subjects, it had little or no beneficial effect in a subgroup of non-responders, possibly because of a difference in the nature of the depression suffered.