Figure 4.

Summary of circadian function in LL. (A) Representative double-plotted actograms taken from WT (dark blue labels) and Egr3−/− littermates (cyan labels) housed in LL for 3 weeks. Wake behavior free runs under LL in mice of both genotypes. (B) Amplitude of the peak periodicity of the Lomb-Scargle periodogram (LSP; power normalized, PN, at tau) in LD (black bars) v. LL housing (gray bars). Rhythms are more robust in Egr3−/− mice under all light schedules tested in the current study (main effect of genotype, F(1, 10) = 8.722, P = 0.0145). Nevertheless, LL weakens rhythms without regard to Egr3 status (main effect of light schedule, F(2, 20) = 6.513, p = 0.0066; genotype × light schedule interaction, F(2, 20) = 0.757, P = 0.4820). (C) Length of the active period (alpha) is shortened in LL in mice of both genotypes, but more so in WT (main effect of lighting condition, F(2, 20) = 58.03, P < 0.0001; main effect of genotype, F(1, 10) = 40.49, P < 0.0001). (D) Tau slows with housing under LL in both Egr3−/− and WT mice. (E) The total amount of time accrued, in hours, in which each minute had >50% to 90% of its epochs defined as “wake” is plotted for each genotype. Even under LL, Egr3−/− mice log more high-percentage waketime than WT animals (repeated measures, 2-way ANOVA, main effect of genotype, F(1, 10) = 7.889, P = 0.0185; main effect of wake category, F(4, 40) = 175, P < 0.0001).