Keywords cryptochrome PDF critical period circadian clock Results Wild-type Canton-S (CS) embryos were exposed to blue light (BL) for 2-h periods prior to, during, and after the characterized embryonic critical period (CP) at 17–19 h after egg laying (AEL).5 Only exposure from 17 to 19 h AEL was sufficient to increase seizure recovery time (RT) at wandering L3 (one-way ANOVA, f(10, 224) = 19.86, p < 0.0001, n = 15, Figures 1A and 1B).