Effects of Circadian Disruption on Mental and Physical Health
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Circadian (daily) rhythms in physiology and behavior are phylogenetically ancient and are present in almost all plants and animals. In mammals, these rhythms are generated by a master circadian clock in the suprachiasmatic nucleus of the hypothalamus, which in turn synchronizes “peripheral oscillators” throughout the brain and body in almost all cell types and organ systems. Although circadian rhythms are phylogenetically ancient, modern industrialized society and the ubiquity of electric lighting has resulted in a fundamental alteration in the relationship between an individual’s endogenous circadian rhythmicity and the external environment. The ramifications of this desynchronization for mental and physical health are not fully understood, although numerous lines of evidence are emerging that link defects in circadian timing with negative health outcomes. This article explores the function of the circadian system, the effects of disrupted clocks on the brain and body, and how these effects impact mental and physical health.
KeywordsBiological rhythms Sleep Aging Obesity Metabolic syndrome Plasticity Prefrontal Hippocampus Learning Depression Circadian disruption
Conflicts of interest: I.N. Karatsoreos: has received grant support from the Canadian Institute of Health Research.
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- 2.Moore-Ede MC, Sulzman FM, Fuller CA. The clocks that time us: physiology of the circadian timing system; 1984.Google Scholar
- 7.•Buhr ED, Yoo SH, Takahashi JS. Temperature as a universal resetting cue for mammalian circadian oscillators. Science. 2010;330:379–85. This article uses a clever technique to demonstrate that the central SCN brain clock is not sensitive to temperature changes, whereas peripheral clocks can be synchronized by temperature. It is important because it highlights a difference between the brain clock and peripheral clocks that may underlie how these different clocks become synchronized or desynchronized.PubMedCrossRefGoogle Scholar
- 16.•Scheer FA, Hilton MF, Mantzoros CS, Shea SA. Adverse metabolic and cardiovascular consequences of circadian misalignment. Proc Natl Acad Sci U S A. 2009;106:4453–8. This article demonstrates that even a single night of circadian misalignment in humans is enough to perturb metabolic regulation, with some subjects showing postprandial glucose responses similar to a prediabetic state. It is important because it highlights the fact that both acute and chronic misalignment can contribute to metabolic dysregulation.PubMedCrossRefGoogle Scholar
- 25.•Karatsoreos IN, Bhagat S, Bloss EB, et al. Disruption of circadian clocks has ramifications for metabolism, brain, and behavior. Proc Natl Acad Sci U S A. 2011;108:1657–62. This paper explores the effects of circadian disruption in an organismal context, showing that chronic circadian disruption results in changes to metabolism, brain, and behavior in mouse. It is important because it demonstrates that environmentally driven circadian disruption can affect multiple brain and body systems, and highlights the fact that it is unlikely a single gene or molecular pathway can explain the effects of circadian disruption.PubMedCrossRefGoogle Scholar