title: Sleep loss, circadian mismatch, and abnormalities in reorienting of attention in night workers with shift work disorder.
abstract: OBJECTIVE
  Permanent night-shift workers may develop shift-work disorder (SWD). In the current study, we evaluated neurophysiological and behavioral indices of distractibility across times prior to the night shift (T1), during night hours (T2), and after acute sleep deprivation (T3) in permanent hospital night workers with and without SWD.
  
  
  METHODS
  Ten asymptomatic night workers (NW) and 18 NW with SWD participated in a 25-h sleep deprivation study. Circadian phase was evaluated by dim-light salivary melatonin onset (DLMO). Objective sleepiness was evaluated using the Multiple Sleep Latency Test (MSLT). Electrophysiological distractibility was evaluated by brain event-related potentials (ERP), whereas behavioral distractibility was evaluated by performance on a visual task in an auditory-visual distraction paradigm.
  
  
  METHODS
  Comparisons of ERP results were performed by repeated-measures analysis of variance, and t-tests were used where appropriate. A Mann-Whitney U test was used for comparison of variables (MLST, Stanford Sleepiness Scale, and DLMO) that deviated from normal.
  
  
  RESULTS
  First, in the SWD group, the reorienting negativity ERP amplitude was significantly attenuated compared to that in the NW group. Second, the SWD group had shorter MSLT during night shift hours (4.8 ± 4.9 min) compared to that in NW (7.8 ± 3.7 min; U = 47; z = -2.1; P < 0.03). Third, NW with SWD had a DLMO at 20:27 ± 5.0 h, whereas healthy NW had a DLMO at 05:00 ± 3.4 h (U = 43.5; z = -2.22, P < 0.03). Finally, acute sleep deprivation impaired behavioral performance and the P3a ERP in both groups.
  
  
  CONCLUSIONS
  Our results demonstrate specific deficits in neurophysiological activity in the attentional domain among the shift-work disorder group relative to night workers.
authors.affiliation: Henry Ford Health System, Sleep Disorders and Research Center, Detroit, MI.
authors.forename: Valentina
authors.initials: V
authors.lastname: Gumenyuk
authors.affiliation: Henry Ford Health System, Sleep Disorders and Research Center, Detroit, MI.
authors.forename: Ryan
authors.initials: R
authors.lastname: Howard
authors.affiliation: Henry Ford Health System, Sleep Disorders and Research Center, Detroit, MI.
authors.forename: Thomas
authors.initials: T
authors.lastname: Roth
authors.affiliation: Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL.
authors.forename: Oleg
authors.initials: O
authors.lastname: Korzyukov
authors.affiliation: Henry Ford Health System, Sleep Disorders and Research Center, Detroit, MI.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Drake
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology* / Q000528:radiation effects; D001921:Brain / Q000502:physiology / Q000528:radiation effects; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects; D005071:Evoked Potentials / Q000528:radiation effects; D005260:Female; D006761:Hospitals; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism; D017286:Polysomnography; D012892:Sleep Deprivation / Q000503:physiopathology* / Q000523:psychology*; D020178:Sleep Disorders, Circadian Rhythm / Q000503:physiopathology* / Q000523:psychology*; D012894:Sleep Stages / Q000502:physiology / Q000528:radiation effects; D018709:Statistics, Nonparametric; D014940:Work Schedule Tolerance / Q000523:psychology; D000078329:Workforce
chemical_list: D008550:Melatonin
keywords: ERPs; Shift work disorder; circadian phase; distractibility