Overview and Description of Circadian Rhythm Sleep Disorders

Circadian rhythm sleep disorders (CRSD) are sleep disorders that result from a misalignment between the endogenous circadian system and the desired sleep-wake schedule. The etiology varies depending on the disorder but is thought to be the result of either an alteration in the endogenous circadian timing system or a mismatch between the endogenous circadian timing system and the external environment (e.g., jet lag and shift work). The diagnosis of these disorders is primarily based on medical review of symptoms, which vary depending on which of the nine CRSD are present. The sleep complaint must lead to significant impairment in social or occupational functioning, and may not be the result of any other medical, neurological, or psychiatric disorder.