OSCILLATORSThe time-keeping system, dubbed "circadian" from Latin circa diem (about a day), allows light-sensitive beings, including humans, to coordinate their physiology and behaviour to the daily changes in geophysical time (Figure 1). The mammalian network of body clocks is organized in a strictly hierarchical manner. A master oscillator, residing in the paired suprachiasmatic nuclei (SCN) of the hypothalamus ( Figure 1A), synchronizes a myriad of peripheral oscillators situated in each organ ( Figure 1B) on a daily basis. In turn, rhythmicity in the SCN is entrained by external timecues or Zeitgebers (German term for time givers). Daily changes in light intensity, detected by classical photoreceptors and intrinsically light-sensitive retinal ganglion cells expressing
AbstractCircadian rhythms have developed in all light-sensitive organisms, including humans, as a fundamental anticipatory mechanism that enables proactive adaptation to environmental changes. The circadian system is organized in a highly hierarchical manner, with clocks operative in most cells of the body ensuring the temporal coordination of physiological processes. Circadian misalignment, stemming from modern life style, draws increasing attention due to its tight association with the development of metabolic, cardiovascular, inflammatory and mental diseases as well as cancer.This review highlights recent findings emphasizing the role of the circadian system in the temporal orchestration of physiology, with a particular focus on implications of circadian misalignment in human pathologies.
K E Y W O R D Scircadian clock, circadian misalignment, continuous recording of circadian bioluminescence, human physiology How to cite this article: Dibner C. The importance of being rhythmic: Living in harmony with your body clocks. Acta Physiol. 2020;228:e13281. https ://doi.