Figure 1

Experimental protocol and average number of attentional failures across all participants. (A) Participants completed a 9–10 day inpatient protocol, the first 5 days of which are shown here and were included in the present analysis. Participants entered the laboratory on study day 1 and were scheduled to three consecutive sleep opportunities (black bars, in 0 lux) at their habitual time, as determined by the 7 days prior to admission. Light levels during wake on study days 1 and 2 were ~90 lux (white bars). Halfway through study day 3, light levels were dimmed to ~1 lux (gray bars), a level at which they remained for the remainder of the study during wake. On study days 4–6, participants completed an ~30–50-hour constant routine (CR) procedure (hatched bars, 50 hours is shown) in which they were kept awake in a semi-recumbent posture in dim light and fed equicaloric snacks every hour. Following this CR procedure, participants were scheduled to an 8-hour sleep episode at a time shifted 10 hours relative to their habitual time before completing the remainder of the study. Neurobehavioral measures were collected frequently (every 30 minutes – 2 hours during wake), of which measures collected on study day 2 at +8 h after waking and study day 5 during CR at +20 h after waking were used in the present analysis. (B) The mean (±standard deviation) number of lapses (reaction time >500 ms) on the psychomotor vigilance task (PVT) across n = 151 subjects for study days 2, 3, and 4, and up to 24 hours awake during CR on study day 5 (thick gray dashed line in panel A) are shown (filled circles). Individual data points (filled diamonds in panel B) for study day 2 at ~8 h awake and study day 5 at ~20 h awake, which were the focus of analysis in this study, are also plotted. Black bars indicate times of scheduled sleep relative to test times.