A hormone called ________ is believed to play an important role in establishing the body's day-night cycle.
A) thymosin
B) cortisol
C) melatonin
D) aldosterone

Question

Quizplus · Accepted Answer

Melatonin is a hormone secreted by the pineal gland that is responsible for regulating the sleep-wake cycle or circadian rhythm of the body. Melatonin levels rise in the evening and fall in the morning, thus helping us fall asleep at night and wake up in the morning.

A Hormone Called ________ Is Believed to Play an Important