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Insomnia associated with functional impairments in patients with shift work disorder

Patients with shift work disorder and insomnia with normal sleepiness have greater work and attentional impairment on event-related brain potential measures compared with patients reporting insomnia and excessive sleepiness, according to study results.

“Insomnia is strongly linked to functional and cognitive impairments in shift workers, while sleepiness appears to make a smaller contribution,” Ren Belcher, BA, of the Henry Ford Hospital in Detroit, and colleagues wrote. “Insomniacs without excessive sleepiness showed more severe impairments than insomniacs who report excessive sleepiness.”

The researchers recruited 37 night-shift workers for an overnight sleep deprivation study to determine if occupational and functional decline within shift work disorder (SWD) is associated with insomnia and sleepiness. Twenty-six of the participants were diagnosed with SWD.

Participants worked solely on a night shift for at least 6 months or more, and they must have worked at least three or more night shifts weekly, each lasting from 8 to 12 hours. Participants completed an Epworth Sleepiness Scale, two Insomnia Severity Index questionnaires and the Endicott Work Productivity Scale (EWPS). Individuals were required to stay awake for 25 consecutive hours.

Control participants had the lowest scores on the EWPS (12.27) indicating the lowest level of occupational impairment. Patients with SWD who only reported insomnia (alert insomniacs) showed the greatest impairment (25.67) vs. participants who reported insomnia and excessive sleepiness (sleepy insomniacs, 19.55) (P < .05).

In a subscale of the EWPS, alert insomniacs reported greater fatigue than sleepy insomniacs and controls (6.33 vs. 4.82 vs. 3.36).

Belcher and colleagues noted the results should indicate better treatment options for individuals with SWD.

“The occupational productivity results described here are an additional call for the importance of aggressively treating this symptom, as work productivity and safety may improve in response to insomnia treatment,” they wrote.

The researchers acknowledged some study limitations, primarily within the measurement of occupational impairment, where data were self-reported and not tested.

“Research on occupational errors in natural environments is an important next direction for SWD, and intervention trials for SWD treatments should consider measuring work productivity and safety alongside the traditional clinical symptoms.” – by Ryan McDonald

Disclosure: Belcher reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.