MCAT Behavioral Sciences Question 52: Answer and Explanation

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Question: 52

7. Increases in which of the following hormones cause sleepiness?

  • A. Cortisol
  • B. Growth hormone
  • C. Melatonin
  • D. Oxytocin

Correct Answer: C

Explanation:

As light diminishes throughout the day, the pineal gland increases secretion of melatonin, resulting in sleepiness. Cortisol levels, choice (A), increase throughout the early morning, resulting in wakefulness. Growth hormone secretion, choice (B), peaks during slow-wave sleep. Oxytocin, choice (D), is associated with uterine contractions in childbirth, milk letdown, and bonding behavior.

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