Melatonin is the hormone that regulates sleep-and-wake rhythm. Which of the following endocrine glands is responsible for producing melatonin?

Melatonin, the hormone that regulates sleep-and-wake rhythm, is produced by the cells in pineal gland. Both the hypothalamus and pituitary glands coordinate the function of other endocrine glands by producing stimulatory and inhibitory hormones. Adrenal glands produce the hormones cortisol and aldosterone.