Which of the following is true of melatonin?

• A. Melatonin is secreted by the adrenal cortex and regulates metabolism.
• B. Melatonin is primarily responsible for the fight-or-flight response.
• C. Melatonin is produced by the pineal gland and regulates sleep-wake cycles.
• D. Melatonin is a hormone that increases blood glucose levels.

Answer: (C)

Verified step by step guidance

1. Identify the gland responsible for melatonin production: Melatonin is produced by the pineal gland, which is located in the brain.
2. Understand the primary function of melatonin: Melatonin is involved in regulating sleep-wake cycles, helping to control the body's circadian rhythms.
3. Differentiate melatonin from other hormones: Melatonin is not involved in metabolism regulation, fight-or-flight response, or increasing blood glucose levels. These functions are associated with other hormones such as cortisol and adrenaline.
4. Recognize the role of melatonin in the body: Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, helping to wake the body.
5. Clarify misconceptions: Melatonin is not secreted by the adrenal cortex, nor does it play a role in the fight-or-flight response or blood glucose regulation.