Which hormone is released in response to daily variations in light and tends to rise as night falls, peaks at midnight, and falls again as the sun rises?

Melatonin is a hormone being produced by small gland in the brain called pineal gland that helps control sleep and wake cycles. It is also called the sleep hormone because it gives signal that it’s time to sleep. People also used this hormone to adjust the body’s internal clock. It is the hormone that released in response to exposure to sunlight. When the sun sets and night falls, the pineal is activated and begins to vigorously produce melatonin. The amount of melatonin tends to rise as night falls, peaks at midnight, and falls again as the sun rises. It means that it produced more when darker and when the lighter it is; the less melatonin is produced.