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. 2003 Apr 25;549(Pt 3):945–952. doi: 10.1113/jphysiol.2003.040477

Figure 4. Comparison of the PRCs using melatonin onset (DLMOn) and offset (DLMOff).

Figure 4

A and B, PRCs plotted as in Fig. 3, except that all values are single plotted. The horizontal dashed line represents the anticipated 0.54 h average delay drift of the pacemaker between the pre- and post-stimulus phase assessments. The fitted peak-to-trough amplitude of the DLMOn PRC (5.41 h) appears slightly larger than that of the DLMOff PRC (4.60 h). C, correlation between the DLMOn and DLMOff phase shifts. The continuous line with a slope of unity represents identical phase shifts between the two phase markers. The dotted line is the linear regression through the data points with a slope (0.84) significantly less than unity (P < 0.05). This indicates that both phase advances and phase delays determined using DLMOff tend to be smaller than those determined using DLMOn.