In the ADHD group, significant phase associations were found for CRY1‒SIRT1 (R = 0.74, R2 = 0.55, p = 0.0039), CLOCK‒LRP6 (R = 0.73, R2 = 0.53, p = 0.005), CLOCK‒CTNNB1 (R = 0.69, R2 = 0.48, p = 0.009), PER3‒SIRT1 (R = -0.63 (inverse), R2 = 0.39, p = 0.022), and PER3‒FOXO1 (R = -0.59 (inverse), R2 = 0.35, p = 0.032). This evidence concerns the gene PER3 and attention deficit-hyperactivity disorder.