The International Classification of Diseases (ICD-10-CM, 2014) lists 6 subtypes of circadian rhythm sleep disorder:
- Delayed sleep phase-type.
- Free-running type.
- Advanced sleep phase-type.
- Irregular sleep-wake type.
- Shift work type.
- Jet lag type.
- As well as unspecified, other, and conditions specified elsewhere.
The DSM-V defines Circadian Rhythm Sleep-Wake Disorder as follows:
A persistent or recurrent pattern of sleep disruption that is primarily due to an alteration of the circadian system or to a misalignment between the endogenous circadian rhythm and the sleep-wake schedule required by an individual’s physical environment or social or professional schedule. The sleep disruption leads to excessive sleepiness or insomnia, or both. The sleep disturbance causes clinically significant distress or impairment in social, occupational, and other important areas of functioning.