Zeitgebers refer to external cues that reset the biological clock to be synchronized with the outside world. Light is the most important Zeitgeber, or time-giver in humans.

In the context of psychology, zeitgebers are environmental cues that help regulate the timing of an organism's biological rhythms, particularly its circadian rhythm. These cues can be light, temperature, social interactions, or other factors that help synchronize an organism's internal clock with the external environment. The term "zeitgeber" is German for "time giver."

Here are some examples of zeitgebers:

  1. Light: The presence or absence of light is one of the most important zeitgebers for regulating the circadian rhythm. Exposure to light in the morning helps reset the internal clock, while exposure to light in the evening can disrupt it.

  2. Temperature: Changes in temperature can also serve as a zeitgeber. For example, a drop in body temperature at night can help promote sleep.

  3. Social interactions: Social cues such as meal times, exercise routines, and work schedules can also help regulate the circadian rhythm.

  4. Sound: Auditory stimuli can serve as zeitgebers as well. For example, the sound of an alarm clock in the morning can help regulate sleep-wake cycles.

  5. Other environmental cues: Other environmental cues such as the timing of meals, the availability of food, and the presence or absence of noise can also affect the circadian rhythm.

Zeitgebers play an important role in regulating the body's internal clock, and disruptions to these cues can lead to problems such as jet lag, sleep disorders, and mood disorders.