RELATION OF LIGHT AND EXERCISE TO SEASONAL DEPRESSIVE SYMPTOMS - PRELIMINARY DEVELOPMENT OF A SCALE

The palliative effects of exercise on depression are neither generally accepted nor clearly understood. On the contrary, the efficacy of lig ht exposure in the treatment of seasonal depressive symptoms is widely recognized. It is possible that the contradictory findings in the exe rcise and depression literatures are due to a failure to consider ligh t exposure as a variable. 32 women who regularly exercised were admini stered a depression inventory and the Seasonal Light Inventory, a new measure composed of two 10-item subscales, Seasonality and Light Expos ure. Seasonality assesses fluctuations of mood, appetite, sleep, and o ther activities occurring al similar times each year, and the Light Ex posure subscale measures respondents' estimated exposure to outdoor an d bright indoor light. Indeed, those exercisers whose habits exposed t hem to a relatively large amount of light reported fewer seasonal depr essive symptoms than those whose habits exposed them to a relatively s mall amount of light. The results suggest that the puzzling relationsh ip between exercise and depression might be delineated more dearly by considering light exposure as a confounding variable.