Which gland produces melatonin?

• A. Pineal gland
• B. Pituitary gland
• C. Hypothalamus
• D. Thyroid gland

Answer: (A)

Melatonin is produced by the pineal gland. This small gland in the brain releases melatonin mainly in darkness, helping signal the body that it’s time to sleep and to regulate the circadian rhythm. Light detected by the eyes lowers melatonin production, while darkness boosts it. The pathway starts with light input reaching the retina, which informs the brain’s circadian clock in the suprachiasmatic nucleus; this clock coordinates signals through the autonomic nervous system to stimulate the pineal gland to convert serotonin into melatonin at night. The other glands listed have important hormonal roles, but they do not produce melatonin.