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This week's theme: words borrowed from German.

zeitgeber (TSYT-ge-buhr) noun

An environmental cue, such as light, that helps to regulate the biological clock in an organism.

[Coined by 1954 by Jürgen Aschoff (1913-1998), from German Zeit (time) + Geber (giver).]

Zeitgebers are events that keep our circadian rhythms regulated. The alternation of the light/dark cycle of a 24-hour day is the most important natural zeitgeber. Another is the earth's magnetic field. An alarm clock is an example of an artificial zeitgeber.

Interestingly, it is claimed that humans' circadian clock has a 25-hour cycle, unlike the earth's 24-hour rotation cycle. In an experiment, subjects lived in a house without windows. There were no external cues, such as clock, television, etc. to give them a hint of when to wake up, eat, sleep, etc. Participants in this study showed a natural rhythm of a 25-hour cycle of sleep, waking up, activity, etc.

Shift work and jetlag owing to rapid travel are some of the activities that can disrupt our circadian rhythms.

-Anu Garg (garg AT wordsmith.org)

"According to Hallow, the eight-hour work day is also a zeitgeber, but one that interrupts the body's natural desire to rest between 3 and 4 p.m." Jill Jedlowski and Erica Jacobson; A midday Nap Can Be a Valuable Pick-me-up; The State Journal-Register (Springfield, Illinois); Nov 9, 1998.


Take long walks in stormy weather or through deep snows in the fields and woods, if you would keep your spirits up. Deal with brute nature. Be cold and hungry and weary. -Henry David Thoreau, naturalist and author (1817-1862)

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