Figure 1.
Raster plot of the 10-day experimental protocol for subject 19a1. Scheduled sleep episodes (8 hours in darkness) are illustrated as black bars. During the baseline days (days 1–3), subjects were exposed to ~90 lux during wakefulness (16 hours). For the remainder of the study, except during the light exposure session, subjects were exposed to ~1.5 lux during wakefulness (gray bars). A ~ 26.2-h constant routine (CR1) was scheduled on days 4–5. The light exposure session (white bar) was scheduled on days 5–6, and consisted of 6.5 hours of exposure centered 5.8 hours before habitual wake time (i.e., it started ~1.1 h before habitual bedtime and ended ~2.6 h before habitual waketime). Following the light exposure day, subjects underwent a 64-h CR (CR2) and were discharged after an ~22-h recovery sleep episode. Dim light melatonin onsets (DLMOn25%) in CR1 and CR2 are indicated by △. For this subject, the light exposure (BL condition) generated a phase delay of 3.15 h in the DLMOn25%.