The circadian rhythm sleep disorder, shift work type (or shift work disorder), is characterized by complaints of insomnia or excessive sleepiness as a result of a work schedule that takes place during the normal sleep period. Shift-work schedules include late evening, night, very early morning, and rotating shifts. Total sleep time is often reduced by 1 to 4 hours in shift workers, even after apparently successful habituation to shift work.1
- American Academy of Sleep Medicine. The international classification of sleep disorders: diagnostic and coding manual. 2nd ed. Westchester, Ill: American Academy of Sleep Medicine; 2005.