Abstract
Circadian oscillations play a critical role in coordinating the physiology, homeostasis, and behavior of biological systems. Once thought to only be controlled by a master clock, recent high-throughput experiments suggest many genes and metabolites in a cell are potentially capable of circadian oscillations. Each cell can reprogram itself and select a relatively small fraction of this broad repertoire for circadian oscillations, as a result of genetic, environmental, and even diet changes.