Serotonin in the morning, melatonin at night. Melatonin is the hormone of the pineal gland. It regulates the inner clock thus ensuring a healthy regenerating rhythm of sleeping and waking. Your skin becomes smooth, your sexual activity and your mental performance will increase. Melatonin helps effectively to overcome the “jet lag” that occurs after long air flights. It has been proven in various studies that Melatonin induces sleep.