Effects of short duration morning bright light in healthy elderly subjects. I:Subjective feeling and ophthalmological examinations

Seven aged subjects aged 61-78 years were exposed to 6000 lx bright light for 30 min during morning hours at their homes for 1 week. Visual analog scale was recorded before bedtime and after rising to assess subjective feelings. Ophthalmological examinations were made before and after light exposure, to exclude pre-existing ocular disorders and to detect ocular damage. Furthermore, ocular fatigue was self-evaluated immediately before and after exposure. Visual analog scale results indicated that alertness reduced significantly before bedtime. Ophthalmological abnormalities were not found after exposure. These findings suggest that short duration morning bright light exposure reduces night-time vigilance.