The results of the Baltimore Longitudinal Study of Aging, which included 1264 participants without cognitive impairment, show that the ε4 allele of the APOE gene is associated with the increased probability of having short-sleep (OR = 1.41, 95% CI 1.06–1.88) but not with the sleep-onset or sleep-maintenance problems [43]. The gene discussed is APOE; the disease is Cognitive impairment.