Joke H. Meijer

Prof. Meijer is one of the very few researchers to incorporate concepts from complexity theory into chronobiology, enabling her to capture the dynamic, nonlinear interactions between sleep, light, and activity, and how these shape circadian function over time. Her work has revealed the critical role of both sleep and activity in modulating the SCN—findings that reshaped our understanding of the brain’s timing system. She also identified the neurotransmitters responsible for photic entrainment (glutamate, GABA) and the principle of seasonal encoding through phase coordination within the SCN. This refined the mechanistic picture of how the brain encodes and adjusts to time.

In addition to her pioneering research, Prof. Meijer founded the BioClock Consortium, a nationwide interdisciplinary research initiative in the Netherlands dedicated to investigating how circadian disruption impacts both human health and ecological systems. Through this platform, she mentors a growing number of PhD candidates and postdoctoral researchers, fostering a new generation of scientists committed to applying circadian insights to real-world societal and health challenges.

Her research does not just study the clock—it studies how the brain itself functions as a time integrator, continuously merging inputs from the world outside with cellular processes from within.

For her groundbreaking and integrative contributions to neuroscience and chronobiology, Prof. Meijer received the Aschoff and Honma Prize—the most prestigious international award in the field of biological rhythms.

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 and sleep
6. Identification of differences in photoentrainment mechanisms between nocturnal and diurnal rodents

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.

For more information, see the website: https://www.johannahmeijer.com/.