Most people who work shifts will experience some difficulty with these symptoms—for example waking up after fewer than 7-9 hours of sleep or feeling drowsy while on the job. For people with shift work disorder, however, this is an ongoing problem that continually causes symptoms and starts to interfere with work or family life.
Shift work disorder can be caused by night shifts, rotating shifts, or even an early morning shift. It can cause chronic sleep deprivation, in which a person never catches up on needed sleep and carries a significant “sleep debt” with them. This kind of chronic loss of sleep has serious implications for health, productivity, and safety.