▪ Abstract The core apparatus that regulates circadian rhythm has been extensively studied
over the past five years. A looming question remains, however, regarding how this
apparatus is adjusted to maintain coordination between physiology and the changing
environment. The diversity of stimuli and input pathways that gain access to the circadian
clock are summarized. Cellular metabolic states could serve to link physiologic perception of
the environment to the circadian oscillatory apparatus. A simple model, integrating …