The purpose of this study is to determine the effects of the anticholinesterase drug donepezil on sleep apnea patients. Sleep structure and respiratory parameters will be analyzed by polysomnography.

Cholinergic activity also influences the upper airway opening via central and peripheral mechanisms. Decreased thalamic pontine cholinergic projections may affect respiratory drive leading to both central and obstructive apnea at least in certain degenerative conditions.In contrast to the prolific literature on physical and surgical treatments for sleep apnea there is a dearth of effective pharmacological approaches.Most drugs previously tested for this purpose acted upon monoaminergic and adenosinergic systems and showed unsuccessful or ambiguous results.A previous study showed that donepezil treatment improved apnea-hypopnea index and oxygen saturation in patients with Alzheimer's disease. Treatment also increased REM sleep duration and reduced ADAS-cog scores.Based on these facts we hypothesize that donepezil treatment may be beneficial for sleep apnea patients.

Intervention: Patients will be administered donepezil or placebo. The study has a randomized, double-blind placebo-controlled design. Complete polysomnography will be performed at baseline, after 28 days of drug or placebo treatment, after 15 days drug or placebo washout and after 28 days of CPAP treatment.

Inclusion Criteria:

• diagnosis of obstructive sleep apnea according to American Academy of Sleep Medicine criteria

Exclusion Criteria:

• body mass index > 40
• use of psychoactive drugs
• presence of neurological, cardiological and pulmonary diseases