What is a Zeitgeber?
A zeitgeber is an external cue which influences the operations of the internal clock in an organism. The classical example of a zeitgeber is light, which leads some organisms to wake up, while others go to sleep. An interruption in such cues can confuse an organism, potentially causing health problems and functional difficulties, as demonstrated in numerous studies. The term was coined in 1954 by Jürgen Aschoff, a German biologist who studied circadian rhythms. In German, “zeitgeber” means “time giver,” so in a sense, you could consider a zeitgeber to be like a natural alarm clock, triggering some sort of change in an organism’s internal clock, like a cue to wake up, eat, or engage in various activities. Light is such a powerful zeitgeber that numerous studies have been carried out on the influences of light over the lives of various organisms. Deprivation of light clearly has an influence on health, as does an excess of light, and many people struggle when they travel across time zone
