Figure 1
(A) Raster plot of the short day (20-h) forced desynchrony protocol in mice (n = 5). The first 10:10LD (T20) cycle (baseline/aligned) started at dark-onset (ZT12 of the previous 12:12LD). The dark-onset of the fourth T20 (misaligned) occurred ‘out of the phase’ (beginning of the subjective day based on preceding T24). The dark-onset of the seventh T20 (re-aligned) occurred ‘back in phase’ (beginning of the subjective night based on preceding T24). Periodogram (Lomb-Scargle; P < 0.0001) analyses were performed on the activity/temperature data from 2nd T20 cycle until 11th T20 cycle (between dark blue arrows). EEG data were scored for vigilance states (VS) of the baseline (black rectangular open box), misaligned (red box) and re-aligned (blue box) cycles. (B) Actograms revealed both a 20 and a 24-h rhythm component for gross activity and core body temperature under T20 conditions. (Upper) Double plotted actograms for motor activity and temperature of a representative mouse under a 20-h LD cycle. The vertical dashed lines of the actograms denote the light and dark phases of the 20-h rhythm component. The diagonal lines of the actograms indicate the onset of the 24-h rhythm component. (Lower) Lomb-Scargle periodograms of the time series represented on the actograms. The analysis yielded statistically significant peaks (P < 0.0001) for the τ ~24-h and the T 20-h rhythms (black arrows). The numbers on top indicate the period of the significant peaks in hours. (Top-right) Table representing the averaged periods (AVG ± SD, B6: n = 5) of the 20 and 24-h rhythms. Statistics are indicated by P values for the equality of variance test showing that the 20-h component of activity (19.9-h) had a smaller variance (SD = 0.3) compared to the 24-h component of activity. (Bottom-right) Averaged histograms (AVG ± SEM) of the power of period peaks revealed a trend for an increase in the τ ~24-h core body temperature power compared to T 20-h core body temperature (indicated by the double-headed arrow; P = 0.062, paired t-test).
