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Research Overview

Circadian rhythms have developed as an adaptation to the recurring changes in the environment brought about a.o. by the cycle of day and night. In order to anticipate these changes, innate clocks have evolved in all organisms. Prof. Johanna Meijer studies the neurophysiological basis underlying clock adaptation to the 24-hour cycle of the environment and to the seasonal cycles in daylength.

She identified the wide range of colors that affect the clock, including UV, and described their effect on the electral activity of clock neurons. She identified the neurotransmitter involved in photoentrainment (glutamate) and the neurotransmitter involved in phase formation between the ventral and dorsal clock regions (GABA). She developed in vivo recordings allowing to investigate the properties of the clock as an integral part of the central nervous system. Her discoveries were awarded with the Aschoff and Honma Prize, the most prestigious recognition in biological rhythm research.


Major discoveries

  1. Identification of the mechanism for photoperiodic encoding by the central clock
  2. Identification of glutamate neurotransmitter for entrainment to the external light-dark cycle and GABA neurotransmitter for entrainment within the central clock
  3. Discovery of role for short wavelength photoreceptor in photoentrainment
  4. Identification of blue, green, and red light response in the central clock of humans by fMRI
  5. Identification of clock response to physical activity

Contributions to circadian research

Prof. Johanna Meijer has made contributions to the field through her research on the effects of clock disturbances on human health, including aging, depression, ADHD, fragile X, and cancer-related fatigue. Additionally, she has conducted pioneering research on small molecules that enhance clock function. By applying complexity approaches, she has further developed our understanding of the mutual interactions between the clock, brain, and behavior.


Recent highlights

2020: Ten million euro research grant for the BioClock consortium by the Dutch National Research Agenda      The BioClock consortium focuses on maintaining a healthy biological clock, addressing human health, biodiversity and the environment. With over 10 million euros in funding, Prof. Johanna Meijer has united eight Dutch universities and 25 partners. Furthermore, the project involves 24 PhD students and five postdocs, and is led by researchers from these institutions. The consortium aims to develop strategies on medical, social, and biodiversity issues, that contribute to a sustainable future for our planet and its inhabitants. Find more information on BioClock Consortium.

“A multi-million grant to keep the biological clock healthy” – Department of Cell & Chemical Biology, LUMC.

2019: Development of a low cost approach to produce COVID-19 respiratory masks                                              April 2020: Meijer & Oude Vrielink (2020): Using surgical wrapping material for the fabrication of respiratory masksPLOS ONE. As a community outreach project, this paper has been shortened and made available in over 17 languages.

It is freely obtainable through a dedicated website: https://coronamedicalmasks.org/  260.000+ visits from 150+ different countries.


Major publications


Awards and recognitions

  • 2021: Member of Academia Europaea
  • 2020: Dutch National Research Agenda Grant of 10.2 million euros– “BioClock Consortium”
  • 2020: “Ambassador of the Night” Initiative of the Dutch Nature and Environment Federation
  • 2019: European Advanced Research Grant of 2.2 million euros, ERC: “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)
  • 2015: C.U Ariens Kappers Award from the Netherlands Society for the advancement of Sciences, Medicine, and surgery- 2015
  • 2015: Board member, National Research Agenda (NWO) Complexity cluster; successfully raised 19.5 million euros on Dutch Complexity Research
  • 2014–Present: Member of the Royal Dutch Society of Sciences
  • 1999: ‘Best teacher’ award for the period 1994-1999 of the study “BioPharmaceutical Sciences” at Leiden University
  • 1993: “Aschoff’s Rule, a prize for eminent contributions in Chronobiology supporting the interdisciplinary spirit of the field” from Prof. J. Hall (noble prize winner)
  • 1989: Fellowship of the Royal Dutch Academy of Sciences