bio

Zeitgeber

Any environmental signal that recurs regularly enough to reset an organism's internal clock. The word is borrowed straight from German - "time-giver" - because German chronobiologists named it first. On Earth light outranks everything else, but temperature cycles, regular feeding times, and even social contact can do the job more weakly. A good zeitgeber must be sharp and reliable: something that only shows up intermittently is nearly useless to a clock.