What happens if people live in an environment in which the cycle of light and dark is other than 24 hours?
A) Within a few days, they adjust to waking and sleeping on the new schedule, whatever it is.
B) They adjust better if the cycle is some multiple of 24 (e.g., 48).
C) They adjust better if the cycle is close to 24 (e.g., 25).
D) They fail to adjust at all.

Question

Quizplus · Accepted Answer

Humans have an internal biological clock that runs on a cycle of approximately 24 hours, known as the circadian rhythm. However, this rhythm can be reset or entrained by external cues, primarily light exposure. If people live in an environment with a cycle of light and dark that is different from 24 hours, they will gradually adjust their sleep-wake pattern to match the new cycle. Research suggests that people can entrain to cycles that differ by up to two hours from their natural rhythm, and that they adjust better if the cycle is closer to 24 hours rather than a multiple of 24. Therefore, answer C is the best choice.

What Happens If People Live in an Environment in Which