AQP4 and early-onset autosomal dominant Alzheimer disease: <h4>Purpose</h4>This review aims to examine how sleep-dependent glymphatic function contributes to the clearance of brain metabolites involved in Alzheimer's disease (AD), with particular emphasis on amyloid-beta (Aβ), tau, astrocytic aquaporin-4 (AQP4), and emerging biomarkers of clearance-related dysfunction.<h4>Method</h4>A narrative review of recent mechanistic, preclinical, and human studies was conducted to synthesize current evidence linking sleep, glymphatic transport, and AD pathophysiology.