EFFECTS OF BRIGHT LIGHT ON SLEEPINESS, MELATONIN, AND 25-HYDROXYVITAMIN D-3 IN WINTER SEASONAL AFFECTIVE-DISORDER

Sixteen patients with winter seasonal affective disorder and 13 health y control were exposed to 3300 lx of cool-white fluorescent light for either 1 hour or 15 min in the morning for 2 weeks during the winter. Subjective sleepiness, melatonin concentration in saliva, and serum 25 -hydroxyvitamin D-3 concentration were measured before and after the 2 -week trial as well as the following summer when the patients were wel l. There were no significant differences in the baseline values betwee n the patients and healthy subjects. No significant differences in the outcome measures were observed in the patients or the control in the two groups of each after the trial. The exposure to bright light resul ted in a significant decrease in subjective sleepiness early in the ev ening in the patients but not in the control subjects. The reduction o f depressive symptoms was associated with the decrease in subjective s leepiness but not with the changes in the melatonin or vitamin D conce ntrations.