Figure 1.

Participants completed a 9 day laboratory protocol. The protocol is depicted in relative clock time with a relative bedtime of midnight. White bars represent wake episodes in <190 lux, black bars represent scheduled sleep episodes with lights off (0 lux), gray bars represent wake episodes in dim light (<3 lux) not under CR conditions, and bars with a diagonal pattern represent the CR in dim light (<3 lux). The checkered bar represents the 6.5 h light exposure occurring 4.75 h postwake on day 6. The wake episode for the CR includes an additional 30 min not under CR conditions, during which time participants prepared for bed. The study schedule consisted of (1) three baseline nights with 8:16 h sleep/wake schedule, (2) a 49 h 40 min CR, followed by an 8 h sleep opportunity, (3) a 6.5 h nighttime light exposure starting 4.75 h postwake, followed by an 8 h sleep opportunity, and, finally, (4) a second 29 h 40 min CR followed by an 8 h sleep opportunity and then discharge (study days not shown).