CIRCADIAN-RHYTHM SLEEP DISORDERS - PATHOPHYSIOLOGY AND TREATMENT

The prediction that abnormalities of circadian clock function in human s would manifest principally as sleep/wake disruption led to the descr iption of the first circadian sleep/wake disorders almost 20 years ago . Since then, formal classification of sleep pathology has expanded th is category to include six specific disorders. In this review, the phy siology of mammalian circadian clocks is summarized with emphasis on t he role of light and hormonal signals in circadian adjustment and entr ainment. Each of the circadian sleep disorders-time zone change (jet l ag) syndrome, shift work sleep disorder, irregular sleep/wake pattern, delayed sleep phase syndrome, advanced sleep phase syndrome, and non- 24-h sleep wake disorder-is reviewed Presenting characteristics, appro aches to diagnosis, models of pathophysiology, and methods of treatmen t are summarized for each sleep disorder. Developments in the understa nding of circadian physiology offer promise for important advances in the diagnosis and treatment of these sleep disorders.