The comorbidity between obstructive sleep apnea (OSA) and insomnia (COMISA) is common, and associated with poorer sleep quality. CPAP adherence among COMISA patients is worst than among those with OSA only. The investigators will compare the effect of Eszopiclone 3mg or placebo for 14 days on adherence to CPAP after 30 days and after 6 months.

The comorbidity between OSA and insomnia (COMISA) is common. COMISA leads to additive impairment of quality of sleep and quality of life compared to patients with insomnia or OSA alone. Patients with COMISA demonstrate worse adherence to CPAP compared to patients with isolated OSA. The best therapeutic approach for patients with COMISA is still unclear. Hypnotics have not been tested among patients with COMISA and indication for CPAP.

The investigators will compare the effect of Eszopiclone 3mg or placebo for 14 days on adherence to CPAP after 30 days and after 6 months. In addition, the investigators will assess the effect eszopiclone on insomnia severity, quality of life, anxiety.

Inclusion Criteria:

• Clinical diagnosis of Insomnia;
• Moderate or severe OSA (AHI ≥ 15 events/h), diagnosed by polysomnography.

Exclusion Criteria:

• Craniofacial anatomical abnormalities or severe otorhinolaryngological disorders that potentially impair CPAP use;
• Use of hypnotics for more than 7 days in the last 2 months;
• Renal dysfunction (serum creatinine >2mg/dL);
• Severe liver or cardiac dysfunction;
• Alcoholism;
• Previous CPAP or mandibular advancement device for OSA treatment in the last 12 months.

double-blind