Figure 2

Experimental Light Treatments. Volunteers were randomly assigned to three four-hour light treatments (detailed in this figure) administered on four consecutive days against a background of <0.5 lux during eight-hour sleep periods and 50 lux during 16-hour wake periods. Treatment A was two hours at 3,000 lux from 1–3 hours and 13–15 hours after arising. Treatment B was four hours at 3,000 lux from 6–10 hours after arising. Treatment C was four hours of dim red light placebo from 6–10 hours after arising. Note that the center of each treatment was eight hours after arising, and the abscissa was hours after usual wake time.