Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light

Abstract

The effects of two non-drug treatments (physical exercise and bright light) on mood, body weight and oxygen consumption were compared in age-matched groups of female subjects with winter depression, non-seasonal depression or without depression. It was found that oxygen consumption in the pre-treatment condition was similar in non-depressed subjects ( n=18) and depressed non-seasonals ( n=18), while comparatively lower values were obtained in winter depression ( n=27). Neither mood nor metabolic parameters changed significantly in the group of nine untreated winter depressives. One week of physical exercise (1-h pedaling on a bicycle ergometer between 13.00 and 14.00 h) increased oxygen consumption in the group of nine winter depressives and lowered oxygen consumption in nine-subject groups of depressed and non-depressed non-seasonals. One week of bright light treatment (2-h exposure to 2500 lux between 14.00 and 16.00 h) increased oxygen consumption in nine winter depressives and nine non-depressed subjects, while no significant change in oxygen consumption was found in nine subjects with non-seasonal depression. Weight loss was observed in the groups treated with physical exercise and in the group of light-treated winter depressives. Winter depression responded equally well to exercising and light, while a significant therapeutic difference in favor of exercising was found in non-seasonal depression. Overall, the results of the study suggest that energy-regulating systems are implicated in the antidepressant action of the non-drug treatments.