title: A Rodent Model of Night-Shift Work Induces Short-Term and Enduring Sleep and Electroencephalographic Disturbances.
abstract: Millions of people worldwide are working at times that overlap with the normal time for sleep. Sleep problems related to the work schedule may mediate the well-established relationship between shift work and increased risk for disease, occupational errors and accidents. Yet, our understanding of causality and the underlying mechanisms that explain this relationship is limited. We aimed to assess the consequences of night-shift work for sleep and to examine whether night-shift work-induced sleep disturbances may yield electrophysiological markers of impaired maintenance of the waking brain state. An experimental model developed in rats simulated a 4-day protocol of night-work in humans. Two groups of rats underwent 8-h sessions of enforced ambulation, either at the circadian time when the animal was physiologically primed for wakefulness (active-workers, mimicking day-shift) or for sleep (rest-workers, mimicking night-shift). The 4-day rest-work schedule induced a pronounced redistribution of sleep to the endogenous active phase. Rest-work also led to higher electroencephalogram (EEG) slow-wave (1-4 Hz) energy in quiet wakefulness during work-sessions, suggesting a degraded waking state. After the daily work-sessions, being in their endogenous active phase, rest-workers slept less and had higher gamma (80-90 Hz) activity during wake than active-workers. Finally, rest-work induced an enduring shift in the main sleep period and attenuated the accumulation of slow-wave energy during NREM sleep. A comparison of recovery data from 12:12 LD and constant dark conditions suggests that reduced time in NREM sleep throughout the recorded 7-day recovery phase induced by rest-work may be modulated by circadian factors. Our data in rats show that enforced night-work-like activity during the normal resting phase has pronounced acute and persistent effects on sleep and waking behavior. The study also underscores the potential importance of animal models for future studies on the health consequences of night-shift work and the mechanisms underlying increased risk for diseases.
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.|College of Medical Sciences, Washington State University, Spokane, Washington, USA.|Sleep and Performance Research Center, Washington State University, Spokane, Washington, USA.
authors.forename: Janne
authors.initials: J
authors.lastname: Grønli
authors.affiliation: Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Meerlo
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
authors.forename: Torhild T
authors.initials: TT
authors.lastname: Pedersen
authors.affiliation: Department of Psychosocial Science, University of Bergen, Bergen, Norway.|Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
authors.forename: Ståle
authors.initials: S
authors.lastname: Pallesen
authors.affiliation: Dr. Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland Univeristy Hospital, Bergen, Norway.
authors.forename: Silje
authors.initials: S
authors.lastname: Skrede
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Marti
authors.affiliation: College of Medical Sciences, Washington State University, Spokane, Washington, USA.|Sleep and Performance Research Center, Washington State University, Spokane, Washington, USA.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Wisor
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
authors.forename: Robert
authors.initials: R
authors.lastname: Murison
authors.affiliation: Section of Psychiatry, Department of Clinical Medicine, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway.|Division of Mental Health Care, Valen Hospital, Fonna Local Health Authority, Valen, Norway.
authors.forename: Tone E G
authors.initials: TE
authors.lastname: Henriksen
authors.affiliation: Sleep and Performance Research Center, Washington State University, Spokane, Washington, USA.|Mathematics and Computer Science, Whitworth University, Spokane, Washington, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rempe
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.|Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
authors.forename: Jelena
authors.initials: J
authors.lastname: Mrdalj
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D004576:Electromyography / Q000379:methods; D006801:Humans; D008297:Male; D023421:Models, Animal; D017208:Rats, Wistar; D012146:Rest / Q000502:physiology; D012307:Risk Factors; D012890:Sleep / Q000502:physiology*; D020178:Sleep Disorders, Circadian Rhythm / Q000503:physiopathology; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology; D014940:Work Schedule Tolerance / Q000502:physiology*
keywords: circadian; shift work; sleep deprivation; sleep disturbance; sleep restriction; slow-wave energy