PER3 and attention deficit-hyperactivity disorder: One-way ANOVA in the ADHD group revealed statistical significant differences between cultures incubated with ATO and negative controls for Clock (F = 6.703, p = 0.004), Bmal1 (ZT16, F = 5.372, p = 0.010; ZT28, F = 3.372, p = 0.047), Per2 (F = 3.335, p = 0.048) and Per3 (ZT0, F = 5.836, p = 0.007; ZT8, F = 2.465, p = 0.027).