Melatonin is a hormone produced in the pineal gland of mammals that aids in the regulation of sleep/wake cycles.* This product is specially designed to mimic the typical nighttime release pattern of melatonin. The first stage releases approximately 0.25 mg of melatonin within 30 minutes followed by a delayed release of the remainder about 3 to 4 hours later. NOW® Melatonin is synthesized according to the highest pharmaceutical standards of quality and purity.