ICSD-3 Diagnostic Criteria [6]:


Clinical Characteristics: Individuals who work night shift experience difficulty with sleep and alertness at desired times, and are at greater risk for the variety of adverse health outcomes associated with poor sleep. Shift workers generally report 30-90 minutes less sleep compared to those not working shifts, and their sleep quality tends to be more fragmented and of poorer quality. Shift workers also experience difficulty falling and staying asleep, with as many as 20% of shift workers having clinically significant insomnia [8]. During waking hours, night shift workers are more prone to increased sleepiness, decreased neurocognitive function and more significant changes to mood than their non-night shift counterparts.
