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 (tsīt′gĕb′ər, zīt′-)
An external stimulus or cue, such as daylight or a regularly repeated occurrence, that serves to regulate an organism's biological clock.

[German Zeitgeber : Zeit, time; see Zeitgeist + Geber, giver (from geben, to give, from Middle High German, from Old High German geban; see ghabh- in Indo-European roots).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biology) biology an agent or event, such as light or the tide, that triggers the biological clock of organisms
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈtsaɪtˌgeɪ bər)
an environmental cue, as the length of daylight or the degree of temperature, that helps to regulate the cycles of an organism's biological clock.
[1970–75; < German (1954), literally, time-giver]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Until recently, it was assumed that the circadian rhythm is entrained in the embryos independent of the brooding female and that the ambient light/dark cycle is the agent that sets the rhythm (zeitgeber).
Supplementary exposure to bright light (i.e., light therapy) has beneficial effects on sleep, depression, bradykinesia, rigidity, and dyskinesias in PD patients, as light activates the suprachiasmatic nucleus and is the most effective zeitgeber of the circadian timing system.
So, the current study was aimed to evaluate impact of inflammation and anesthesia on cognition by quantifying BDNF protein in the hippocampus and cortical areas at 3rd day of treatment at ZT5 (Zeitgeber Time 5).
After 52 wk of exposure, 4 to 5 mice from each experimental group were daily randomly sacrificed (in total, 16 to 20 animals from the four experimental groups were sacrificed per day) by cervical dislocation at Zeitgeber time 17 (i.e., in the fed state) at which hepatic activities are optimal (Lu et al.
Wever, "Re entrainment of circadian rhythms after phase shifts of the Zeitgeber," Chronobiologia, vol.
Though light operates as their chief zeitgeber (from the German zeit = time; geber = giver, or synchronizing agent), the SCN can interpret several exogenous and physiological time-of-day cues to entrain other satellite oscillators in the periphery and their respective signaling networks [15].
The German ornithologists also found that light intensity is a primary factor, a "Zeitgeber" for the birds' dispersal and their circadian activity.
The SCN needs daily synchronization to adapt to environmental 24- light-dark cycles, and light is the major synchronizer (zeitgeber).
All animals were exposed to 1.5% concentration of isoflurane or to 6 L [min.sup.-1] [O.sub2] for six hours between Zeitgeber Time (ZT) 0-ZT06 (day-time administration) or ZT12-ZT18 (night-time administration).
Results of several murine studies showed that timing to food access, in the fasting state, is the cue "Zeitgeber" to entrain hepatic oscillators [33, 52-55, 59] and thereby evoke upregulation of mRNA and various protein synthetic pathways, including enzymes that play a role in carbohydrate and lipid metabolism [33,59].
LD cycle is a well-known zeitgeber that synchronize the clock components both in vitro and in vivo, allowing the rhythmic expression of several clock-controlled molecules.