title: Dim light at night disturbs the daily sleep-wake cycle in the rat.
abstract: Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12 h light (150-200lux):12 h dark (LD) schedule or a 12 h light (150-200 lux):12 h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily rhythms of REM and NREM sleep, with a further decrease over the following days. LDim diminished the rhythms of 1) the circadian 16-19 Hz frequency domain within the NREM sleep EEG, and 2) SCN clock gene expression. LDim also induced internal desynchronization in locomotor activity by introducing a free running rhythm with a period of ~25 h next to the entrained 24 h rhythm. LDim did not affect body weight or glucose tolerance. In conclusion, we introduce the first rodent model for disturbed circadian control of sleep due to LAN. We show that internal desynchronization is possible in a 24 h L:D cycle which suggests that a similar desynchronization may explain the association between LAN and human insomnia.
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Dirk Jan
authors.initials: DJ
authors.lastname: Stenvers
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Rick
authors.initials: R
authors.lastname: van Dorp
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ewout
authors.initials: E
authors.lastname: Foppen
authors.affiliation: Institute of Cellular and Integrative Neurosciences, CNRS UPR3212, University of Strasbourg, France.
authors.forename: Jorge
authors.initials: J
authors.lastname: Mendoza
authors.affiliation: Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
authors.forename: Anne-Loes
authors.initials: AL
authors.lastname: Opperhuizen
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Eric
authors.initials: E
authors.lastname: Fliers
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Bisschop
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Johanna H
authors.initials: JH
authors.lastname: Meijer
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.|Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
authors.forename: Andries
authors.initials: A
authors.lastname: Kalsbeek
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Tom
authors.initials: T
authors.lastname: Deboer
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000528:radiation effects*; D008027:Light; D008297:Male; D017208:Rats, Wistar / Q000502:physiology*; D012890:Sleep; D014851:Wakefulness