zeitgeber

Merriam-Webster's Word of the Day for February 4, 2024 is: zeitgeber \TSYTE-gay-ber\ noun

Zeitgeber refers to an environmental agent or event (such as the occurrence of light or dark) that provides the stimulus which sets or resets an organism’s biological clock.

// The ratio of daylight to darkness in the spring is an important zeitgeber that affects the activity of some migrating birds.

[See the entry >](https://www.merriam-webster.com/dictionary/zeitgeber)

Examples:

“Which digital rhythms are we actively following because they make us feel good, and which are we [entrained](https://www.merriam-webster.com/dictionary/entrain) to? Entrainment, a term that originated in biology and then spread to the social sciences, refers to the alignment of an organism’s physiology or behavior with a cycle; the most familiar example would be our circadian rhythm. The signal driving entrainment, in this case light and dark, is called a ‘zeitgeber’ ...” — Jenny Odell, The New York Times, 8 Dec. 2022

Did you know?

Zeitgebers are alarm clocks—both biologically and etymologically. The word zeitgeber comes from a combination of two German terms: Zeit, meaning “time,” and Geber, which means “giver.” In nature, zeitgebers tend to be cyclic or recurring patterns that help keep the body’s circadian rhythms operating in an orderly way. For earthlings of all kinds, the daily pattern of light and darkness and the warmer and colder temperatures between day and night serve as zeitgebers, cues that keep organisms functioning on a regular schedule—consider how the changing ratio of day to night in spring serves as a trigger for critters such as birds and [spring peepers](https://bit.ly/3tMRiNr) to sing their mating songs. For humans, societally imposed cycles, such as the schedule of the work or school day and regular mealtimes, can become zeitgebers as well. What you sing is up to you, however.