Insomnia in shift work disorder (SWD) associated with cortical excitability: an ERP study prior to a night shift.
Gumenyuk-V; Howard-R; Roth-T; Roehrs-T; Drake-C
Sleep 2013 Jun; 36(Abstract Suppl):A199
Introduction: Hyperarousal as a characteristic of primary insomnia may be reflected in neuronal excitability of the central auditory system. Currently, it is unknown whether insomnia (INS) in the context of shift work (SWD-INS) is characterized by elevated amplitude of the N1 auditory brain response measured by event-related brain potentials (ERPs). Insomnia is also associated with cognitive processing deficits. This study examined the N1 as a measure of neuronal excitability and the MMN as a measure of cognitive processing in SWD-INS during the night. Methods: 5 night-workers with SWD-INS (38+/-10.3yrs. 1 male; ESS 7.8+/-1.2: ISI 15.5+/-3.9) and 9 asymptomatic night workers (ANW) (31.5+/-5.5yrs, 3 males; ESS 7.9+/-1.7: lSI 6.6+/-2.8) participated. All worked a 10-12hr shift between 19:00 and 08:00 and were free of other sleep disorders and otherwise healthy. The ERP session started at 18:00. The peak latency of N1 elicited by an infrequent sound (frequency deviant) was measured between 90-110 ms from sound onset. The MMN was elicited when the brain pre-attentively detected a frequency change in the sound-sequence and was measured between 130-160 ms from sound onset. Evaluation of sleepiness was performed by a standard MLST starting at 22:30. Results: Mean MSLT score from 22:30 - 02:30 was not significantly different between groups (9+/-5min [ANW] vs. 10+/-8min [SWD-INS]), but the ISI differed (15.5+/-3.9 [SWD-INS] vs. 6.6+/-2.8 [ANW] p<.02). The N1 amplitude was significantly elevated in SWD-INS relative to ANW (-1.7+/-O.8 microV vs. -1.1+/-0.6 microV, p<0.0 1). MMN was not significantly different between SWD-INS and ANW (-0.9 microV+/-0.8 microV vs. -1.0 microV+/-0.7microV). Conclusion: Cortical excitability is present in SWD-INS and can be objectively determined by the N1 brain response in the auditory modality. In the wake state, SWD-INS is not associated with a deficit of sensory memory.
Sleep-deprivation; Sleep-disorders; Shift-work; Shift-workers; Brain-electrical-activity; Brain-function; Brain-matter; Auditory-system; Work-intervals; Humans; Men; Age-groups; Physiological-response; Sound; Sensory-perceptual-processes; Mental-processes; Nervous-system
V. Gumenyuk, Sleep Disorders and Research Center, Henry Ford Hospital, Detroit, MI, USA
Henry Ford Health System, Detroit, Michigan