Chronobiology investigations have revealed much about cellular and physiological
clockworks but we are far from having a complete mechanistic understanding of the
physiological and ecological implications. Here we present some unresolved questions in
circadian biology research as posed by the editorial staff and guest contributors to the
Journal of Circadian Rhythms. This collection of ideas is not meant to be comprehensive
but does reveal the breadth of our observations on emerging trends in chronobiology and
circadian biology. It is amazing what could be achieved with various expected innovations
in technologies, techniques, and mathematical tools that are being developed. We fully
expect strengthening mechanistic work will be linked to health care and environmental
understandings of circadian function. Now that most clock genes are known, linking these
to physiological, metabolic, and developmental traits requires investigations from the single
molecule to the terrestrial ecological scales. Real answers are expected for these questions
over the next decade. Where are the circadian clocks at a cellular level? How are clocks
coupled cellularly to generate organism level outcomes? How do communities of circadian
organisms rhythmically interact with each other? In what way does the natural genetic
variation in populations sculpt community behaviors? How will methods development for
circadian research be used in disparate academic and commercial endeavors? These and
other questions make it a very exciting time to be working as a chronobiologist.
