Figure 3

Time course of changes in cosine acrophase, amplitude and mesor for equine MT and BT rhythms with a 6-h phase advance of LD12:12 between Day 0 and Day 1. A. Change in acrophase clock time (mean +/- SEM) over Days 0 through 11 of the experiment. B. mean +/- SEM melatonin amplitude and mesor values. C. Means +/- SEM body temperature amplitude and mesor (right y axis) (Range in degrees centigrade: 37.8°C – 38.9°C). Dotted horizontal lines in A represent a 6 h phase advance relative to baseline (upper, MT; lower BT). Note that the consistent steep rise in MT between ZT 12 and 15 on all days suggests a rapid MT shift that is essentially complete (+ 6 h) on Day 1 and stable thereafter (Figure 2A).