Home > Encyclopedia of Mental Disorders > Circadian rhythm sleep disorder

Definition

Circadian rhythm sleep disorder is a persistent or recurring pattern of sleep disruption resulting either from an altered sleep-wake schedule or an inequality between a person's natural sleep-wake cycle and the sleep-related demands placed on him or her. The term circadian rhythm refers to a person's internal sleep and wake-related rhythms that occur throughout a 24-hour period. The sleep disruption leads to insomnia or excessive sleepiness during the day, resulting in impaired functioning.

The Fourth Edition Text Revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IVTR, a handbook used by mental health professionals to diagnose mental disorders) defines circadian rhythm sleep disorder as one of several primary