zeitgeber

/ˈzaɪtɡeɪbər/
noun
  1. An external cue, such as light or temperature, that helps regulate an organism's internal biological clock.
    • Regular meal times can act as a zeitgeber for your body's daily rhythms.
    • Sunlight is the most powerful zeitgeber for setting your sleep-wake cycle.
    • Shift workers often struggle because they lack a consistent zeitgeber like daylight.
Synonyms
What does "zeitgeber" mean? | whatsthatwordmean | whatsthatwordmean