Primary aim of the TURKAPNE (The Turkish Sleep Apnea Database) study is to generate a cross-sectional nationwide database to define clinical and polysomnographic characteristics of the sleep apnea patients in Turkey. Associations of phenotypes of sleep apnea patients with metabolic and cardiovascular diseases as well as risk for traffic accidents will be explored as secondary aims. Impact of treatment of sleep apnea on metabolic and cardiovascular complications as well as compliance with positive airway pressure treatment will be further explored longitudinally.