Although studies indicate that the orexin levels in cerebrospinal fluid (CSF) are associated with circadian alteration in AD and the OXA levels are positively correlated with the cognitive function in AD (Liguori et al., 2020; Shimizu et al., 2020), the dysregulation of the orexinergic system in AD remains inconclusive. The gene discussed is HCRT; the disease is Alzheimer disease.