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by Eric Bittman
I am pleased to share a film I made to supplement assigned readings in my undergraduate course on Biological Rhythms at the University of Massachusetts. I have divided the video into 7 parts, and it is my practice to assign the various chapters at appropriate points during the semester as the course covers various topics. In addition, it gives students a chance to meet some of the important contributors to our field, who generously gave their time for interviews.

It is provided with the hope that those teaching courses in biological rhythms will find it useful in introducing students to the history and concepts of our field. I am happy to provide the syllabus I have used upon request, as an example of how the chapters can be integrated with reading assignments and discussions.

Here’s an outline of the organization:

Prologue (starts at 0030): An introduction to circadian rhythms with speculation on evolutionary/cellular origins.
Chapter 1 (starts at 05:12): History of the study of biological rhythms (up until mid- 20th century).
Chapter 2 (starts at 27:45): End of the Endogenous-Exogenous debate
Chapter 3 (starts at 37:18): Adaptive significance of endogenous rhythms (including photoperiodism and sun compass orientation).
Chapter 4 (starts at 59:50): Entrainment (including phase response curves and some mathematical modeling).
Chapter 5 (starts at 1:24:05): Genetics and molecular mechanisms
Chapter 6 (starts at 1:34:09): Circadian pacemakers



ChronoHistory materials are available after login to the SRBR members’ site via ClockTool page, a comprehensive information system for all chronobiologists.

The Committee on ChronoHistory is charged with identifying, evaluating, recommending and implementing initiatives and mechanisms to ensure preservation of the history of our discipline, Chronobiology. The relative youth of our field and its growth and richness are counter-balanced by the aging and loss of founders and early contributors.

Preserving this history provides a basis for conceptual understanding of our field, and a sense of intellectual kinship. In addition, Chronobiology is viewed as a field of remarkably fast growth in integrative power since its formal foundation in the 1950s. Preserving materials that document this process are therefore valuable for a more general understanding of the generation of new ideas and research fields.

Aims of the ChronoHistory Committee include:

    1. Developing a historical record, including scanned photos with identification of individuals, and commissioning essays.
    2. Developing and implementing an archive, including recommendations as to where and how it is established and maintained.
    3. Identifying opportunities to interview and record salient figures in our history.
    4. Soliciting input from the SRBR membership regarding their ideas, wishes and ways the history may be used.
    5. Producing recommendations for further weaving ChronoHistory into our SRBR website.
    6. Identifying and securing sources of financial support to ensure accomplishment of these aims.

We encourage SRBR members to contribute to this effort through the submission of historical documents, photographs, texts and/or anecdotes, references and other material, including multimedia files.

To ensure the quality of material within ChronoHistory, the content of contributions for public collections will be curated by the ChronoHistory committee of the SRBR. Please contact to submit materials for review.

ChronoHistory Videos


Further ChronoHistory materials are available after login to the SRBR members’ site via ClockTool page, a comprehensive information system for all chronobiologists.


  • Landmarks of Circadian Research
  • Video History Collection
  • Colin S. Pittendrigh Repository
  • History of Rhythms Publications
  • Historical Archives
  • Prizewinners of Aschoff’s Rule
  • Clock References, a repository of bibliographic entries of chronobiologists, and hard-to-access documents such as old manuscripts and PhD theses. So far all available papers of Aschoff and Wever, Pittendrigh, Hastings, Gwinner, Bünning, Engelmann, Daan, Arendt, and Menaker have been collected and scanned.

as well as

  • Clock Images
  • Clock Classes, materials used for Chronobiology-related classes
  • Clock Links
  • Clock Tools, a repository of software tools used in chronobiology for analyzing and simulating experimental data and producing graphs and pictures