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Cortical arousal is present in alert insomniacs but absent in sleepy insomniacs within shift work disorder: an ERP study.
Gumenyuk-V; Belcher-R; Drake-CL; Spear-L; Roth-T
Sleep 2014 Mar; 37(Abstract Suppl):A178
Introduction: Consistent with research showing hyperarousal in insomnia, we previously demonstrated cortical arousal in the insomnia-only phenotype of Shift Work Disorder ("alert insomniacs," AI). Neurophysiologically, this cortical arousal is reflected by enlarged amplitude of the waking N1 ERP response. We now test whether cortical arousal is also present in night-workers with insomnia and excessive sleepiness ("sleepy insomniacs," SI). Methods: 12 AI (37.1 +/- 11.0 years, ESS = 7.3 +/- 2: ISI = 14.6+/- 3.1), 11 SI (36.6 +/- 9.4 years, ESS = 11.2 +/- 3.5: ISI = 14.2 +/- 4.8), and 12 controls (32.8 +/- 6.9 years, ESS = 6.7 +/- 3.1: ISI = 4.9 +/- 3.2) participated in an ERP, overnight MSLT, and phase assessment study. Subjects with a history of insomnia or other sleep disorders prior to shift work were excluded. The N1 responses to frequency-deviant [FD], duration-deviant [DD],and standard [STD] auditory stimuli were measured at a latency of 90-120 ms. The N1 peaks corresponding to each type of stimulus were compared by ANOVA. All other measures were compared between groups by t-tests. Results: In AI, the peak of N1 to each stimulus was significantly (p < 0.01) enlarged (-1.5 +/- 0.3 microV [STD], -2.2 +/- 0.9 microV [FD] and -1.9 +/- 0.6 microV [DD])over the frontal-central electrodes compared to SI (-0.9 +/- 0.6 microV [STD], -1.2 +/- 0.6 microV [FD], and -1.3 +/- 0.6 microV [DD]) and to controls (-0.9 +/- 0.5 microV [STD], -1.3 +/- 0.7 microV [FD] and -1.1 +/- 0.6 microV [DD]). N1 peaks were similar in SI and controls. MSLT was significantly (p < 0.01) lower in SI (3.1 +/- 3.0) compared to AI (7.8 +/- 5.1) and to controls (8.1 +/- 3.4). DLMO was significantly (p < 0.01) later in controls (04:54 +/- 3.7 h) than in both SWD groups: AI (22:45 +/- 4.9 h) and SI (20:55 +/- 4.6 h). ISI was correlated (r = -.69; p = 0.01) with N1 in AI group and was not correlated (r = -.07) in SI or controls. Conclusion: Cortical arousal, reflected by enlarged N1 brain response, was observed in SWD patients with insomnia only, but not in the SI phenotype or in controls. This suggests that the "insomnia" in the SI phenotype is etiologically different from insomnia seen in the AI group.
Sleep-deprivation; Sleep-disorders; Shift-work; Shift-workers; Brain-electrical-activity; Brain-function; Brain-matter; Auditory-system; Work-intervals; Humans; Age-groups; Physiological-response; Neurophysiological-effects
V. Gumenyuk, Sleep Disorders and Research Center, Henry Ford Hospital, Detroit, MI, USA
Henry Ford Health System, Detroit, Michigan
Page last reviewed: May 3, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division