Insomnia comprises a number of complaints of reduced quality of sleep, initiating and maintaining sleep with varying duration, type and severity. The aetiology is complex and includes entrained and physiological causes found in psychiatric, neurological and medical disorders. The patophysiological background is likely to play a more important role than formerly assumed. The management includes cognitive therapy and lifestyle changes. Medical treatment of psychophysiological insomnia has only a limited role and there is no evidence of any effect of chronic hypnotic treatment.