The purpose of this study is to evaluate sleep quality in patients with mild to moderate Alzheimer's disease treated with anticholinesterase drugs in clinical practice.

This is an epidemiological (the study of health-related states or events in specific populations) study of patients with mild to moderate Alzheimer's who have been treated previously with anticholinesterase drugs (class of drugs that act in the central nervous system) up to a maximum of fifteen days. The data for each patient will be recorded on two occasions; first at a baseline visit and then at a follow-up visit at 3 months. At the baseline visit, after the patient or his/her legal representative has given written informed consent, each participating neurologist will use the study questionnaire to collect patient sociodemographic characteristics (characteristics such as age, years of education, race, sex, religion, birthplace, income, occupation, geographic location, among others), medical history and diagnosis of Alzheimer's disease. The neurologist will also record treatment for Alzheimer's disease and concomitant hypnotic medications (simultaneous use of medications that induce sleep) and evaluate the patient using two scales: the Pittsburgh Sleep Quality Index (PSQI) to record sleep disturbances and the Epworth Sleepiness Scale to determine the level of daytime sleepiness. Alzheimer treatment and concomitant hypnotic medications will be recorded again at the follow-up visit. Patient sleep quality using the PSQI and daytime sleepiness using the Epworth scale will also be evaluated again at this visit.

Inclusion Criteria:

• Patients with a recent diagnosis of possible or probable Alzheimer's disease (National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA criteria) within a maximum of 60 days before the baseline visit.
• Patients with mild or moderate Alzheimer's disease, defined by a Mini-Mental State Exam (MMSE) score between 11 and 25.
• Patients whose caregivers are sufficiently informed of the patients' state and if possible live with the patient.
• Patients who are capable of attending a second clinic visit with their accompanying person 3 months later, based on the clinical practice of the investigator.
• Patients and/or legal representatives who have given and signed written informed consent.

Exclusion Criteria:

• Patients who have psychotic manifestations.
• Patients who have clinically significant sleep disorder (sleep apnea syndrome, restless leg syndrome).
• Patients treated with memantine.
• Patients and/or legal representatives who refuse to give written informed consent to participate in the study.

Patients attending the neurology clinic of participating centers throughout Spain who meet eligibility criteria.