Frontiers in Physiology
Chronobiology is a relatively young and fast evolving research field, which aims at understanding the origin, the mechanisms and the prerogatives of endogenous biological clocks. The Chronobiology section of Frontiers in Physiology provides an interdisciplinary forum for the publication of research covering all aspects of the field, including molecular clock circuitry, clock evolution, animal models, physiology, translational studies, and chronotherapy. Over the past few decades, chronobiology has moved from occupying a specialist niche within physiology research, to influencing every aspect at all levels of the discipline. In 2017, the Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash and Michael W. Young, three chronobiologists and drosophilists, “for their discoveries of molecular mechanisms that control circadian rhythms.” The field went on to receive considerably more interest and attention, and the efforts of those researchers who had been working on chronophysiology and its medical implications and applications were also rewarded as chronobiology entered its true translational era (Cederroth et al., 2019). This has been characterized by a flourishing of relevant, novel clinical observations (to name one, the fact that the outcomes of certain types of cardiac surgery are heavily dependent on time of day; Montaigne et al., 2018), by the evolution and the definition of an almost entirely novel chronobiology vocabulary and, most interestingly, by experiments and observations that constantly challenge the few true dogmas of this relatively young science. The definition of clock cells themselves has changed, moving away from the idea that there are cells with specific features that qualify them as oscillators to a model where the clock or oscillator results from the interaction of distinct physiological players (circadian networks) (Mizrak et al., 2012). Similarly, it has become evident that brain structures other than the suprachiasmatic nuclei (SCN) clock neurons [for example astrocytes within the SCN itself (Hastings et al., 2019), the habenula (Baño-Otálora and Piggins, 2017) and the blood brain barrier (Cuddapah et al., 2019)] exhibit clock properties or produce oscillations that modulate SCN outputs in many different ways. Thus rhythmicity, both circadian and over other time scales (for example seasonal, lunar and tidal) is transforming into an ever more complex, versatile and interesting natural phenomenon. The influence of chronobiology on society at large has also been profound, resulting in campaigns, for example, to modify urban lighting, to amend school times and to abolish daylight saving time (Roenneberg et al., 2019). Amongst these developments, I will now focus on a few that fascinate me and, hopefully, will stimulate you.