Abstract: Sleep disturbances (SDs) in Alzheimer’s disease (AD) may significantly affect the behavioral, functional, and cognitive capacities of patients to the point of becoming a major determinant of caregiver burden. We conducted a cross-sectional study in 125 patients with probable AD to assess the association of SDs with neuropsychiatric symptoms, cognitive and functional status of patients, and severity and duration of dementia and to ascertain the role of antidementia drugs in the treatment of SD. SDs were assessed using the questionnaire on sleep disorders in the Neuropsychiatric Inventory. The prevalence of SDs in this sample was 36%. SDs in patients with AD are significantly associated with depression (Wald’s test, 3.983; p < 0.05), disinhibition (Wald’s test, 5.522; p < 0.05), and aberrant motor behavior (Wald’s test, 7.430; p < 0.01). The patients treated with memantine presented lower mean SDs scores (t = 2.76; p < 0.001). These results highlight the need for a standardized and validated approach to the assessment of SDs in AD.