Figure 2

Responses to sleep homeostatic challenges in S4 and B6 mice. (A) Wakefulness in hourly bins during undisturbed baseline, sleep deprivation, and recovery opportunity. Black bar at bottom indicates sleep deprivation. Shaded background indicates lights-off. Curves depict group means and s.e.m. The baseline values are replotted from Fig. 1D. The asterisk indicates the significant difference between strains in sleep amounts during the first 2 h of recovery sleep opportunity (p = 0.02). SD = sleep deprivation, RS = recovery sleep (B) NREM delta power in hourly bins during baseline and recovery sleep opportunity. Black bar at bottom indicates sleep deprivation. Shaded background indicates lights-off. Curves depict group means and s.e.m. The amplitude of oscillation was lower in S4 mice. (C) Cumulative NREM delta energy over 24 h. Dashed curves depict baseline values, solid curves depict values during sleep deprivation and recovery sleep. Curves depict mean values and s.e.m. F-value for interaction of factors ‘time’ and ‘strain’ for the sleep deprivation + recovery days is indicated in the panel. Degrees of freedom are 23, 276. Bsl = baseline. (D) NREM EEG power spectra of the first 2 h of RS normalized by the corresponding 2 h of baseline NREM (ZT7 + 8). Curves depict group averages and s.e.m. Interaction of factors ‘frequency’ and ‘strain’ (permutation ANOVA) is indicated at the bottom. The degrees of freedom are 409 and 4908. The p-values for post hoc uncorrected bin-by-bin t-tests are indicated below the spectra. (E) Wake time during the multiple sleep latency test. Curves depict group means and s.e.m. Black bars at bottom indicate the five consecutive 20 min sleep deprivations. (F) Sleep latency and time spent in NREM during the 5 nap opportunities of the MSLT. Asterisk indicates shorter sleep latencies for S4 mice (p < 0.05). (G) NREM delta power during the nap opportunities of the MSLT, normalized by the average baseline values. Curves depict group means in 200 s time bins. Error bars depict s.e.m. Shaded rectangles depict group means ± s.e.m. for a complete nap opportunity. The asterisk by the legend indicates a significant main effect of ANOVA for the factor ‘strain’ (p < 0.05).