title: Environmental 24-hr Cycles Are Essential for Health.
abstract: Circadian rhythms are deeply rooted in the biology of virtually all organisms. The pervasive use of artificial lighting in modern society disrupts circadian rhythms and can be detrimental to our health. To investigate the relationship between disrupting circadian rhythmicity and disease, we exposed mice to continuous light (LL) for 24 weeks and measured several major health parameters. Long-term neuronal recordings revealed that 24 weeks of LL reduced rhythmicity in the central circadian pacemaker of the suprachiasmatic nucleus (SCN) by 70%. Strikingly, LL exposure also reduced skeletal muscle function (forelimb grip strength, wire hanging duration, and grid hanging duration), caused trabecular bone deterioration, and induced a transient pro-inflammatory state. After the mice were returned to a standard light-dark cycle, the SCN neurons rapidly recovered their normal high-amplitude rhythm, and the aforementioned health parameters returned to normal. These findings strongly suggest that a disrupted circadian rhythm reversibly induces detrimental effects on multiple biological processes.
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Eliane A
authors.initials: EA
authors.lastname: Lucassen
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Claudia P
authors.initials: CP
authors.lastname: Coomans
authors.affiliation: Department of Human Genetics, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Maaike
authors.initials: M
authors.lastname: van Putten
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: de Kreij
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Jasper H L T
authors.initials: JH
authors.lastname: van Genugten
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Robbert P M
authors.initials: RP
authors.lastname: Sutorius
authors.affiliation: Department of Radiology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands; Percuros BV, 7522 NB Enschede, the Netherlands.
authors.forename: Karien E
authors.initials: KE
authors.lastname: de Rooij
authors.affiliation: Department of Radiology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: van der Velde
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Sanne L
authors.initials: SL
authors.lastname: Verhoeve
authors.affiliation: Department of Medicine, Division of Endocrinology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Jan W A
authors.initials: JW
authors.lastname: Smit
authors.affiliation: Department of Radiology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Clemens W G M
authors.initials: CW
authors.lastname: Löwik
authors.affiliation: Department of Parasitology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Hermelijn H
authors.initials: HH
authors.lastname: Smits
authors.affiliation: Department of Parasitology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands; Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Bruno
authors.initials: B
authors.lastname: Guigas
authors.affiliation: Department of Human Genetics, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands.
authors.forename: Annemieke M
authors.initials: AM
authors.lastname: Aartsma-Rus
authors.affiliation: Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, 2333 ZC Leiden, the Netherlands. Electronic address: j.h.meijer@lumc.nl.
authors.forename: Johanna H
authors.initials: JH
authors.lastname: Meijer
mesh_terms: D000818:Animals; D001683:Biological Clocks; D002940:Circadian Rhythm; D008027:Light; D008297:Male; D051379:Mice / Q000502:physiology*; D008810:Mice, Inbred C57BL; D017440:Photoperiod; D013493:Suprachiasmatic Nucleus / Q000502:physiology*