How does sunlight banish the BLUES? Most experts believe the Pineal Gland is involved. The Pineal Gland is an obscure gland deep in the brain which secretes the hormone MELATONIN. MELATONIN times the onset of Puberty acts as an internal timekeeper, induces sleep, and influences moods. Melatonin secretion follows a regular daily rhythm. The Pineal secretes high levels of Melatonin at night and low levels of Melatonin during the day. In 1980, Alfred Lewy discovered that bright lights put the brakes on Pineal function while darkness accelerates it. Melatonin's cycle of nature was explained. The light of the day suppresses the secretion of Melatonin, while the darkness of night increases its production. This is how man's hormonal nature is controlled by environmental light. Sunlight can improve our moods and even affect our emotional health.