
5-Hydroxytryptophan (5-HTP), a natural amino acid, is a chemical precursor of biosynthetic neurotransmitters Serotonin and Melatonin. It is used as a dietary supplement, sleep aid, and appetite suppressant and is also marketed for the indication of major depression. In United Kingdom, United States, Australia and Canada, 5-HTP is sold as an over the counter (OTC) product. Serotonin, also called as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter and it regulates the mood, sleep and appetite. Melatonin is a hormone and its effects are produced through the activation of melatonin receptors. Secretion of melatonin reduces with age and leads to insomnia. In North America Melatonin is sold as an OTC product and not regulated by FDA, whereas, in Europe and Asia-Pacific it is a prescription drug.