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 De pression Inventory (BDI) score of 15 (indicating severe depression) an d were consequently given light therapy. The subjects were regularly e valuated with the BDI at 2-week intervals during the months before and after light therapy. The BDI score increased rapidly during the 4 wee ks before treatment and fell immediately after treatment. A marked dec rease in depression score was also seen with the Hamilton Depression R ating Scale (HDRS) and HDRS/SAD extension rating scale. Although light therapy had a beneficial effect in most of our subjects, it had littl e or no beneficial effect in a subgroup of non-responders, possibly be cause of a difference in the nature of the depression suffered.