bims-ciryme Biomed News
on Circadian rhythms and metabolism
Issue of 2026–01–25
two papers selected by
Gabriela Da Silva Xavier, University of Birmingham
  1. Simulated natural daylight and twilight modulate activity and light sampling behaviour in mice.
  2. Time after time - circadian clocks through the lens of oscillator theory.
  1. BMC Biol. 2026 Jan 22.
    Simulated natural daylight and twilight modulate activity and light sampling behaviour in mice.
    Laura C E Steel, Mark W Hankins, Russell G Foster, Stuart N Peirson.
       BACKGROUND: In the wild, mice are subject to changes in light intensity and spectrum (colour) across the solar day. In addition, mice are able to self-modulate their light exposure - a concept termed light sampling behaviour, which results in intermittent patterns of light exposure. These complexities are poorly considered in most laboratory animal housing. As such, our understanding of the role of intermittent exposure to naturally-occurring changes in intensity and spectrum in circadian behaviour are limited. To address these issues we simulated both daylight and twilight in the laboratory, and provided a dark nestbox to enable behavioural regulation of light exposure.
    RESULTS: The results show that gradual changes in light intensity are a key driver of crepuscular light sampling in mice, whilst demonstrating for the first time that spectral cues at twilight modulate the timing of behaviour - advancing locomotor activity by 0.5h and light sampling behaviour by 1.1h.
    CONCLUSIONS: Collectively, our results demonstrate the significance of changes in intensity and spectrum across twilight for regulating mouse behaviour. These findings highlight important differences in mouse behaviour under naturalistic environments compared to normal laboratory conditions.
    Keywords:  Circadian ecology; Circadian rhythms; Daylight; Intensity; Light sampling behaviour; Photoentrainment; Photoreceptors; Spectrum; Twilight
    DOI:  https://doi.org/10.1186/s12915-026-02517-7
  2. FEBS Lett. 2026 Jan 21.
    Time after time - circadian clocks through the lens of oscillator theory.
    Marta Del Olmo, Carolin Ector, Hanspeter Herzel.
      Biological systems are fundamentally rhythmic, with oscillations emerging at multiple scales, from intracellular gene circuits to organ-level coordination. Many of these rhythms, including the circadian clock, arise from feedback-driven genetic networks that interact to produce coherent temporal organisation. In this review, we examine the circadian system as a model for understanding the dynamics of coupled biological oscillators. We introduce the core theoretical concepts of delayed feedback, nonlinearity and coupling, and show how these principles govern the emergence of synchronisation, entrainment, and complex dynamics across cellular populations and tissues. Drawing on tools from nonlinear dynamics, we explore how oscillator models help explain robustness, plasticity, and failure modes in circadian systems. Finally, we discuss how this theoretical framework informs experimental design and translational applications in circadian medicine, from optimising drug timing to understanding rhythm disruptions in disease.
    Keywords:  circadian rhythms; coupled oscillators; coupling; entrainment; limit cycles; oscillator theory; synchronisation
    DOI:  https://doi.org/10.1002/1873-3468.70257
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