[Classification of sleep disorders].

Sleep disorders are frequent processes, both as a symptom associated with other diseases and as independent disorders. However, only in the last 4 decades has Sleep medicine gained its position among the medical specialties. In fact, it was only in these years that significant advances were obtained in the study of the etiology and treatment of these disorders. Similarly, the different classifications have been evolving over the years. First, they were based upon the clinical symptom; later on, more emphasis was given to the diseases. Finally, in 2005, the new classification was once again based on the symptoms. More than 90 disorders are listed in this latest classification, and an attempt is made to include the symptoms and the diseases of sleep, as well as those in which sleep disorders are fundamental. It is essential to have a clear idea of this complete classification of sleep disorders in order to deal with these patients appropriately.