The incidence of chronic insomnia represents 10-15% of general population and in 35-40% patients with insomnia other mental disorder is diagnosed. 10-20% of insomnias are secondary to respiratory disorder in sleep, 10-15% patient have restless legs syndrome and periodic limb movement disorder. Only 10-20% patients have the chronic insomnia without comorbidity.
Three presented cases document the role of polysomnographic examination in diagnostic process and effective treatment.