Research Overview

Circadian rhythmicity is a fundamental feature of biological organization and is deeply rooted in the biology of all living organisms. These rhythms have developed as an adaptation to the recurring changes in the environment brought about by the rotation of the Earth around its axis and the orbit of the Earth around the Sun. In order to anticipate these changes, innate clocks have evolved that allow organisms to prepare for the predictable onset of night and day. Our circadian system evolved as a robust mechanism to increase fitness. However, in modern society, the widespread use of artificial light and electronic devices has drastically—and rather suddenly—changed the photic environment in which we live, and compelling studies now demonstrate that a lack of a proper light-dark cycle is detrimental to human health. Recent data from our group and others showed that deviating from the natural cycles of light and dark can have severe effects on clock function. Reduced function of the central clock causes key organ systems to lose their synchrony and/or 24-hour pattern, increasing the risk of developing a wide range of severe health conditions, including diabetes, neurological and cardiovascular disease, immune dysfunction, cancer, sleep disorders, and depression. With our modern society’s 24-hour economy and our increasing use of artificial light, perturbations in our clock function are likely to continue to increase, underscoring the importance of developing strategies to strengthen clock function.

Topics of the Meijer group

  1. Neuronal network organization of the circadian clock in day active vs night active animals
  2. Light responses of the circadian system (retinal photopigments, jet lag, shift work)
  3. Clinical: aging, sleep, metabolic syndrome, depression, cancer
  4. Sleep and exercise: non-photic effects on the SCN clock
  5. Complexity theory; emergent properties of hierarchical neuronal networks
  6. Chronopharmacology: strategies for enhancing clock function, optimizing drug timing
  7. Field research, ecology, biodiversity, population dynamics, nocturnal light pollution


Recent prizes and awards

  • 2019: ERC Advanced Grant: “The circadian clock in day-active species: preserving our health in modern society”
  • 2016: Aschoff and Honma Prize in Biological Rhythm Research (International Selection Committee, chaired by Dr. Takao Kondo)

Current special positions/functions of JH Meijer

  • 2020: “Ambassador of the Night” (Natuur en Milieufederatie Nederland).
  • Visiting Professor Oxford University
  • Member of the Royal Holland Society of Sciences and Humanities
  • Member of the Life Sciences Board, Lorentz Center, Leiden
  • NWO board ‘Complexity’

Societal Impact