Which of the following hormones regulates functions influenced by light and seasons?

Hormone melatonin, a modified amino acid regulates functions related to light and the seasons. Melatonin is produced by the pineal gland, a small mass of tissue near the center of the mammalian brain. Light has two effects on melatonin: day–night light cycles modify the rhythm of its secretion and brief pulses of light of sufficient intensity and duration abruptly suppress its production. The circadian rhythm of pineal melatonin secretion reflects signals originating in the suprachiasmatic nucleus.