Light Therapy for Elderly Depression

The purpose of this study is to investigate the following two hypotheses: 1. Treatment with bright light improves their sleep, mood, concentration and self-sufficiency of elderly depressed subjects. This clinical improvement is accompanied by decreases in cortisol/DHEA ratio and increases in melatonin concentration in urine and saliva. 2. The eventual beneficial effect of bright light treatment can be predicted by the presence of sleep-wake rhythm disturbances as found using muscle activity registration, and by cortisol/DHEA and melatonin concentrations in saliva and urine over the day and the night.