Shift work sleep disorder
SWSDShift work sleep disorder is a circadian rhythm disorder in which work hours overlapping the normal sleep period cause persistent insomnia, excessive sleepiness, or both.
Roughly one in five workers in industrialized countries works evenings, nights or rotating shifts, and a portion of them develop lasting symptoms because their internal clock, which is set by daylight, keeps signaling wakefulness during the day and sleepiness at night. The result is short, fragmented daytime sleep after a night shift and drowsiness on the job, with the mismatch worsening under rotating schedules that change faster than the clock can adjust. Night workers also tend to eat at irregular hours and get less daylight, which adds to the strain on the clock.
Typical features are difficulty falling or staying asleep, reduced total sleep time, sleepiness during work hours, irritability and reduced concentration, along with a higher rate of accidents and, over years, associations with metabolic and cardiovascular problems. The diagnosis is made from a work and sleep history, sleep diaries or actigraphy covering at least two weeks, and exclusion of other sleep disorders. Management centers on schedule design, timed light exposure, planned naps and protected sleep periods. Cannabinoids have been studied for sleep complaints generally but not specifically for shift work disorder, and evidence remains early.