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Bioscience Initiative - Universiteit Leiden

Bioscience Initiative

Bioscience Initiative
Leiden University

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How biological clocks drive sleep and napping

Van Leeuwenhoek Lecture on BioScience.

Thursday November 29 2018 at 16.00hrs.
Gorlaeus B├Ętacampus LUMY 04.28
Steve Brown

Steven Brown received his Doctorate in Biochemistry at Harvard University (1997).

From 1998 – 2005 he was a postdoc at the Institute of Molecular Biology at the University of Geneva and began his active work on circadian rhythms.

In 2006, as a Humboldt Fellow at the Charité in Berlin, he researched the topic “Molecular mechanisms regulating chronotype”.

Since September 2006 he is Professor of Pharmacology and Toxicology at the Medical Faculty of the University of Zürich.

In the Brown Lab researchers study the molecular mechanisms of mammalian clocks and the ways in which they control behavior and physiology. The approach is a broad one, and includes everything from in-vitro biochemistry and cell biology of cultured cells, to transgenic and knock-out mouse models, to genetic and clinical studies involving human beings. Research efforts of the group are also focused on biomathematical modeling.


Mice are nocturnal, but like many humans they spend half the 24-hour day at rest, and during the activity period they display two peaks of activity separated by a period of quiescence – a daily “siesta”. At the circuit level, siestas and sleep are facilitated by neurons within the suprachiasmatic nuclei (SCN) – the circadian “master clock”. Using optogenetic and chemogenetic approaches, we show that silencing these neurons eliminates a daily siesta, while activating them or mistiming them can create a siesta at will. Thus, sleep is not only a reflection of fatigue, but also a “hard-wired” property encoded by the biological clock. Meanwhile, at a cellular level in cortex, our recent –omics studies suggest that sleep pressure is encoded by a complex transcriptional and translational program at least partly underpinned by subnuclear rearrangement, transport of specific mRNAs to synapses, and their local translation and phosphorylation. These processes in turn are regulated locally both by circadian clocks, and by a sleep homeostat. Together with experiments from many other labs, our research represents the first steps in understanding how the neural circuits of the mammalian circadian clock modulate daily sleep-wake cycles.


Please keep the following dates free in your diary (all Thursdays at 16h.):


January 31 2019, Tjeerd Barf (Oss, Acerta Pharma)

February 21 2019, Jan-Willem Veening (Lausanne, Fundamental Microbiology)

March 28 2019, Richard Smith (Düsseldorf, Max Planck Inst. for Plant Breeding)

April 11 2019, Valerian Dolja (Oregon State University, Genome Research and BioComputing)

May 23 2019, Pamela Yeh (UCLA, Ecology and Evolutionary Biology)

June 27 2019, Nick Lane (London University College, Evolutionary Biochemistry)

September 26 2019, Rob Phillips (Pasadena, Caltech, Biology and Biological Engineering)