Circadian rhythm sleep-wake disorder, shift work type

**Definition:** Circadian rhythm sleep-wake disorder, shift work type is characterised by complaints of insomnia and/or excessive sleepiness that occur as a result of work shifts that overlap with all or a portion of conventional nighttime sleep periods. The disorder is also associated with a reduction in total sleep time. The symptoms should have persisted for at least several months and result in significant distress or mental, physical, social, occupational or academic impairment.