Figure 3

Profiles of aMT6s excretion. Examples of urinary aMT6s interpretation are plotted for one male participant, age 61 years (A and C), and one female participant, age 28 years (B and D). Panels A and B plot aMT6s (ng/h) in blue longitudinally during the two segments of continuous collection used for baseline and post-treatment phase assessment. The abscissa is h from the midnight commencing the first laboratory day (broken axis to omit 2 days of treatment). A cosine curve was fit to the 24 h immediately prior to the first light pulse (white bar) and again to the last 24 h. The horizontal red dotted lines represent the mesors (fitted means) associated with each cosine. Filled circles show the time of the cosine acrophases before (black), and after (grey) light treatment. Times of aMT6s onsets and offsets are represented respectively by upward and downward pointing arrows (black arrows for baseline and grey arrows for post-treatment.) The light-induced phase shifts in circadian aMT6s profiles are illustrated in panels C and D by replotting both baseline (1, black line) and post-stimulus curves (2, red line) on a noon-to-noon abscissa. In A and C, light given 8–11 PM, elicited phase delays of -5.0, -3.3, and -5.9 h, respectively, in the aMT6s acrophase, onset and offset. In B and D, the light stimulus given 5–8 AM produced phase advances of 1.2, 1.1, and 1.1 h, respectively. Note that the phase shifts were well-demonstrated despite the lower aMT6s excretion in the older participant.