[Insomnias: I. Aetiology, pathophysiology and diagnostics].

Difficulties to initiate or maintain sleep, early morning awakening and resulting impairment of daytime functioning are a frequent comorbidity of many psychiatric and medical disorders. The so-called primary or psychophysiological insomnia as a distinct independent form of insomnia is a far less frequent condition. This article gives an overview of the diagnostic process for insomniac disorders. Furthermore, up to date neurobiological models of insomnia are discussed.