Figure Caption 0. Cellular to Organismal Timekeeping: Communication Between Clocks.

The mammalian circadian clock is a coupled network of cell and tissue clocks. Light and food are predominant cues, pushing and pulling on the phase, enhancing or attenuating the amplitude and activating or inhibiting functional rhythms. In a tissue-specific manner, clocks receive input signals and convert them into timed functional outputs, many of which in turn act as inputs, effectively connecting the network.