Figure 4. Robustness, amplitude, and mesor of URs in decreasing photoperiods.

Mean ± SEM (A) robustness, (B) amplitude, and (C) mesor of the dark phase (filled/black bars) and light phase (open/white bars) ultradian waveforms in 15 L and after transfer to one of seven experimental photoperiods ranging from 9 L to 15 L (indicated along the abscissae). *P≤0.05 and **P≤0.005 vs. 15 L value, within photophase.