Effect of short duration morning bright light in elderly men: Sleep structure

Sleep structure was measured in five healthy elderly men in their homes. Th e subjects were exposed to bright light (60001x) for 30 min in the morning or instructed to sit In front of a desktop lighting device without light. R elative to the control conditions, bright light exposure significantly decr eased time in bed and the number of awakenings. Rapid eye movement sleep wa s significantly fragmented by stage 1 sleep in the control condition compar ed with the bright light condition. These findings indicate that a short du ration of morning bright light changes sleep structure and is effective in maintaining sleep.