Obstructive sleep apnea (OSA), characterized by intermittent hypoxia and arousal-related sympathetic surges, further destabilizes autonomic and vascular rhythms and shifts the expression of core clock genes (BMAL1, CLOCK, PER1, CRY1), reinforcing blunted or inverted BP profiles [86–90]. The gene discussed is CLOCK; the disease is obstructive sleep apnea syndrome.