APOE and early-onset autosomal dominant Alzheimer disease: Sleep disruption has been proposed to play a role in increasing amyloid β (Aβ) deposition,1,2,3 the defining characteristic of the preclinical phase of Alzheimer disease, thought to begin decades before symptom onset.4 Increasing age and the ε4 allele of the APOE gene are principal risk factors for Aβ deposition.