[Diagnosis and classification of sleep disorders].

When sleep was recognized as an active process which is regulated by the interaction of homeostatic and circadian systems a new understanding of sleep disturbances set in, and sleep medicine developed as a new medical speciality. An internationally recognized classification system was developed which allows to diagnose the different sleep disturbances reliably. Sleep disorders comprise (a) dysregulations of the sleep-wake system (insomnias, hypersomnias, narcolepsy, parasomnias), (b) sleep associated disturbances of functional systems (for example sleep apnea, restless legs syndrome), (c) disturbances of the circadian sleep-wake rhythm, and (d) sleep disturbances in association with other organic or psychiatric illnesses. The present contribution shows the diagnostic procedures for four main sleep disorders, namely insomnia, obstructive sleep apnea (OSAS), restless legs syndrome (RLS), and narcolepsy.