Melatonin is a hormone that is produced naturally by the pineal gland. At night, higher levels of melatonin is held by the body to induce and maintain sleep. The normal cycles of melatonin production are altered due to factors including aging, medications, and light exposure at night. Something as small as travel, working nights or possibly using a computer screen may greatly impact melatonin's production. Melatonin is a natural sleep aid having hypnotic and relaxing effects, which helps to maintain a regular sleep cycle.