Figure 4.

Baseline time course of plasma corticosterone levels. Mean (± SEM; n = 4/time point; 8 samples/mouse; total n = 12; see Methods) time course of changes in plasma corticosterone (black symbols and line; left y-axis). Gray line indicates best fit Gaussian function (r = 0.86, P < 0.0001, n = 24 data points; estimated peak time 11.0 ± 0.3 h; nonlinear regression). Fit values were used as the force driving for the baseline changes in Per2 expression (Figure 3A, middle panel). Values were normalized to fit a 0 to 1 scale (right y-axis). Gray areas delineate the dark period.