Fig. 1

Double raster plots of the times of predicted low performance and alertness for the five schedules. In a raster plot, time in hours is plotted across the horizontal axis and time in days are plots vertically from the top. For this plot; 48 h are plotted horizontally; therefore the data on the right half of each line is duplicated on the left half of the next line. Times when performance (top panel) or alertness (bottom panel) are predicted to be less than that after 16 h (yellow bars) or 24 h (red bars) wake at habitual time are shown