5-HTP, also known as L-5-hydroxytryptophan, is a substance that occurs naturally in the human body. It is produced from the amino acid tryptophan and is a precursor of serotonin, an important neurotransmitter in the brain.
Melatonin is a sleep hormone. It controls the day-night rhythm in the human body. Melatonin is produced by serotonin. The production takes place in the pineal gland. This is a tiny gland in the brain, which is also called the pineal gland.