What aspect of circadian rhythms might explain why we tend to feel so tired at night?
A) Body temperature bottoms out on Monday mornings.
B) The three biorhythm patterns converge at low points on Mondays.
C) Heart rates typically increase at night.
D) Part of the brain is sensitive to light changes, which then affects our sleepiness.

Question

Quizplus · Accepted Answer

Part of the brain, specifically the suprachiasmatic nucleus (SCN), is sensitive to changes in light, which signals to our bodies that it is time to sleep. As the day progresses and it gets darker, the SCN releases more melatonin, a hormone that promotes sleepiness. This explains why we tend to feel tired at night when it is dark outside.

What Aspect of Circadian Rhythms Might Explain Why We Tend