Fig. 1.

Protocol and circadian melatonin timing (n = 6). (A) In-laboratory protocol with time of day plotted as relative clock hour with scheduled waketime arbitrarily assigned a value of 0800 h and all other times referenced to this. The open rectangle represents room light (<40 lx), black rectangles represent scheduled sleep, and gray rectangles represent scheduled wakefulness in dim light (<1 lx). On study day 2 subjects were circadian aligned, and on study day 4 subjects were circadian misaligned. Red circles represent the timing of blood collection for proteomics analyses. B, breakfast; D, dinner; L, lunch; S, snack. (B) Melatonin levels during circadian alignment (black line) and misalignment (red line). Gray shading represents the average fitted melatonin values across circadian alignment and misalignment conditions. Black- and red-outlined rectangles represent scheduled sleep opportunities during circadian alignment (habitual sleep) and circadian misalignment (daytime sleep), respectively. Data are mean ± SEM.