Efficacy and Safety of Ramelteon in Subjects With Mild to Moderate Alzheimer's Disease

Inclusion Criteria * Clinical diagnosis of dementia of the Alzheimer's type (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition Revised) or probable Alzheimer's disease by National Institute of Neurological and Communicative Disorders and Stroke/the Alzheimer's Disease and Related * Disorders Association criteria. * Female subjects must be post-menopausal. * Stable residence with no planned move during the entire investigation period. * Residing in the same residence with a responsible spouse, family member, or a professional caregiver who is present during the night who would agree to assume the role of the principal caregiver for the duration of the protocol period. * Able to ingest oral medication and participate in all scheduled evaluations. * Clinical laboratory evaluations (including clinical chemistry, hematology, and urinalysis) within the reference range as tested by the designated laboratory unless the results are deemed not clinically significant by the investigator or sponsor. * Treatment medications for any non-excluded medications or concurrent medical conditions are stable for 30 days prior to the screening visit and medication(s) can in the investigator's judgment, remain stable throughout the duration of the study. * Mini-Mental State Examination score of 8 to 28, inclusive. * History of greater than or equal to 2 sleep disorder behaviors, occurring at least once weekly over the two weeks before screening. * Actigraphy evidence shows a nightt…