Figure 5. The peaks of 12 h cycling genes correlate with subjective dusk and dawn.

Rhythmic transcripts detected by COSOPT and Fisher's G-test at a false-discovery rate of <0.05 were median-normalized and plotted as a heatmap for 24, 12 and 8 h cycling genes (A–C). Bright yellow represents expression 2-fold greater than median levels while bright blue represents expression less than 50 percent of median levels. The time of peak expression of 24 h cycling genes show a roughly equal distribution over the course of a day; in contrast, the peak expression of both 12 h rhythms are biased to specific times each day.