Figure 2

Time course of the change in melatonin concentration. Time course of the difference in melatonin concentration between the light conditions and DL (in 2 h bins). The horizontal black line represents the baseline under DL. The difference in melatonin concentration between BL and DL is depicted in light blue in the young (solid line) and in dark blue in the older (dashed line), and the difference between WL and DL is in red in the young (solid line) and in violet in the older (dashed line).