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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 at the Circadian Clock lab 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

Find more information at the Circadian clock lab of the Leiden University Medical Center.

Recent highlight

2020: Ten million euro research grant for the BioClock consortium by the Dutch National Research Agenda
“With our BioClock consortium we are going to make sure that the biological clock is, and remains, healthy. Our plans cover the society as a whole: from human health and disease to the natural environment and protection of biodiversity. Topics such as health effects of shift work, optimal times for immunotherapy for cancer and flu vaccinations are all covered,” explains project leader and Professor of Neurophysiology, Joke Meijer.
“This project is unparalleled internationally in the scope and applicability of biological clock research. After years of fundamental research, we can finally start working on concrete applications for society”.
With the biological clock in the center, the partners in the consortium will jointly develop strategies that contribute to a sustainable future for our planet and its inhabitants. The consortium receives almost 10 million euros and has academic and non-academic partners, from the National Institute for Public Health and the Environment (RIVM) to municipalities and from environmental organizations to health and safety services. Find more information on BioClock Consortium 

“A multi-million grant to keep the biological clock healthy” – CCB at LUMC

“Miljoenensubsidie om biologische klok gezond te houden”– Universiteit Leiden

Recent publications:

Recent events

  • Amsterdam Dark Festival public lecture – September 23, 2023
  • Academische Tafel Municipality Amsterdam – September 22, 2023
  • Public lecture at Franeker Academy ‘The role of light in life’ (in Dutch) – March 15th

For students with a possible career in science

COVID-19 Related

Recent prizes, awards, and grants

  • 2020: 9.7 Million euro research grant Dutch National Research Agenda BioClock consortium  Link1 Link2
  • 2019: 2.4 Million euro research grant 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 of Joke Meijer

Societal Impact (For more, see media)