Fig. 1

The effects of light pulses on the locomotor activities and the arousal levels. The white bar shows the light pulses (150 lux) administered to WT (N = 6) and PK2−/− mice (N = 7) during ZT16-ZT18.5 (2.5 h). The analysis bin sizes were 30 min, with values being means ± sem. a. Light pulses significantly inhibited the locomotor activity in the WT mice (P < 0.01, Two-way ANOVA, *, P < 0.05, **, P < 0.01 by Bonferroni’s post hoc test). The effect of light pulses on the locomotor activity of the PK2−/− mice was not significant (P > 0.05, Two-way ANOVA). The insert shows the locomotor activity in the entire 2.5 h (*, P < 0.05, paired t-test). b. Light pulses significantly deceased the wake time in the WT mice (P < 0.0001, Two-way ANOVA, *, P < 0.05, **, P < 0.01, ***, P < 0.001 by Bonferroni’s post hoc test). The inhibitory effect of light pulses on the arousal levels of the PK2−/− mice was only significant for the first 30 min (P < 0.05, Two-way ANOVA, **, P < 0.01, by Bonferroni’s post hoc test). The insert shows the wake minutes of the entire 2.5 h (***, P < 0.001, paired t-test). The inhibitory effect of light pulse on the arousal levels in the entire 2.5 h was not significant for the PK2−/− mice (P > 0.05, paired t-test)