Circadian rhythm sleep-wake disorders refer to a group of conditions in which the timing of sleep is affected. Circadian rhythms are often referred to as the body’s internal clock or the biological clock. Individuals with a circadian rhythm sleep-wake disorder are unable to naturally go to sleep or wake up at the time necessary for their work, school, or social environments.
The circadian rhythm sleep-wake disorders listed in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) include delayed sleep phase type, advanced sleep phase type, irregular sleep-wake type, non-24-hour sleep-wake type, and shift-work type. A diagnosis of a circadian rhythm sleep-wake disorder is only given if the sleep disturbance causes clinically significant distress or impairs an individual’s ability to function in social, occupational, or educational settings.