5-HTP known as 5-hydroxytryptophan or 5-hydroxy-l-tryptophan is a
compound created in the body which is used to regulate serotonin
levels in brain and central nervous system. Serotonin is an important
brain chemical involved in mood, behavior, appetite, and sleep.5-HTP
is a substance that is naturally produced in the body. It can also be
produced commercially by extracting it from the seeds of the African
plant Griffonia simplicifolia and has been used in this form
clinically for over 30 years. The clinical efficacy of 5-HTP is due to
its ability to increase production of serotonin in the brain.

http://www.homeherb.com/specialstore/5-htp.htm