Timing is everything. Just ask a comedian, trapeze artist, Romeo and Juliet — or nearly any cell in your body.
Ticking away inside almost all cells are tiny clocks composed of protein gears. Scientists have known that these molecular clocks govern the daily rhythms of life, from mealtimes and bedtimes to the rise and fall of hormone levels, body temperature and blood pressure. New research shows that circadian clocks, as the daily timekeepers are known, do more than just control day-to-day schedules.