As many other progressive fields of scientific inquiry, the study of circadian rhythms has experienced enormous growth in the recent past. From fungi and plants to birds and mammals, as well as from molecules and cells to organisms and populations, research on circadian rhythms has advanced at full speed into the 21st century. Circadian rhythm research is currently published in prestigious general-science journals such as Nature and Science as well as in specialty journals such as Biological Rhythm Research, Chronobiology International and the Journal of Biological Rhythms. With the continuing expansion of the field, it is natural to create a specialized Journal of Circadian Rhythms.

This new journal, with an editorial board composed of active researchers in a broad range of specialties from a variety of nations, shall foster the dissemination of basic and applied research in the field of circadian rhythms, regardless of whether endogenous mechanisms are the central theme. Related topics, such as photoperiodism and daily torpor, are also welcome. The use of 21st-century technology for publication of the journal is a major component of the enterprise.

Although many publishers of scientific journals have tried to keep up with the electronic age by adding on-line versions of print journals, they have maintained the traditional publishing structure that requires authors to transfer the copyright of their articles to the publisher and that limits the access to published articles by charging for subscriptions, or by at least charging "pay-per-view" fees for individual articles. Although major university libraries have been able to pay for subscriptions to major journals, most potential readers around the world remain without access to a large number of scientific publications.

Various researchers in the United States, Europe, and developing countries believe that scientific publishing in the 21st century will be characterized by open access to (peer-reviewed) articles, freely and universally available on-line to readers worldwide. Two independent initiatives, the Public Library of Science [1] and BioMed Central [2], have embraced the future by starting the publication of on-line journals where authors retain the copyright [3] for their articles and readers can access the articles on-line for free anywhere in the world immediately upon publication [4]. The Journal of Circadian Rhythms takes advantage of BioMed Central's experience of launching over 100 on-line journals to advance the publication of research on circadian rhythms into the 21st century.

In recognition of the fact that embracing the future cannot be accomplished without full understanding of the fundamentals established in the past, I invited Professor Franz Halberg to write the very first article to be published in the Journal of Circadian Rhythms [5]. Halberg, the creator of the term circadian and foremost advocate of the discipline of chronobiology, has been a leading figure in biological rhythm research for over 50 years. The article recounts his trajectory from the discovery of circadian rhythms to the development of the notion of the chronome, a notion that he currently advocates with great enthusiasm through numerous theoretical articles and continuing medical research. Included in the article are recollections of Halberg's interaction with other investigators of biological rhythms such as Erwin Bünning, Curt Richter, Jürgen Aschoff, and Colin Pittendrigh. At my request, Halberg also presents his forecast of future developments in chronobiological research. This is an exceptional opportunity to learn from past accomplishments in the field and to speculate about what the future will bring us. Whatever the future actually brings us, one thing is certain: the Journal of Circadian Rhythms will be on-line 24 hours a day, 7 days a week, bringing the latest research developments in the study of circadian rhythms promptly and freely to readers worldwide. Readers and potential authors are cordially invited to join us in this exciting enterprise.