Efficacy and Safety Assessment of ZOlpidem (Stilnox CR) in Patients With Chronic insomNIA

Inclusion Criteria: \- Primary insomnia diagnosis (difficulty for initiating sleep, or maintaining sleep to wake up to early in the morning, or to present a restless sleep) which causes clinically significant disturbances in the areas of social, work functioning or other important areas Exclusion criteria: * Serious, severe and/or acute respiratory impairment * Severe liver impairment * Hypersensitivity to the formulation components or to some of its active metabolites * Pregnant or breast-feeding women Patients with important associated disorders in SNC and specially psychotic disorders * Patients with the probability of using alcoholic beverages concomitantly (as a precaution measure) * Chronic use of benzodiazepines Moreover, in order to follow the international regulations in terms of the use and handling of hypnotic compounds, and to guarantee the appropriate study performance, no patients with one or more of the following characteristics should be included: * Patients who cannot comply to follow-up * Patients who have any drug abuse problem * Individuals who work changing night shifts or with pathological snoring * Presence (or suspicion) of sleep apnea, periodical legs movements or restless legs syndrome The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.