Figure 2. aMT6s acrophase over the shift schedule.

A, boxplots of aMT6s acrophase time at baseline and at the final successive night shift. Outliers are shown as closed circles. B, clock time of aMT6s acrophase at baseline (D1–D7) and on final night shift (N3 or N4) for each participant plotted by study day. Baseline acrophase is plotted on the day aMT6s was measured, and is assumed to be acrophase immediately prior to night shifts. C, change in aMT6s acrophase time from baseline to third (N3) or fourth (N4) night shift (acrophase at baseline minus acrophase at final night shift). Negative time indicates a phase delay (acrophase occurred at a later clock time after working night shifts compared to baseline), and positive indicates a phase advance (acrophase occurred at an earlier clock time after night shifts than at baseline). Men are represented by closed triangles and women by open circles.