5-HTP is used as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. A person who is coming down from MDMA (which is a psychoactive drug) uses 5-HTP to relieve post-MDMA dysphoria.
5-HTP works in the brain and central nervous system by increasing the production of the chemical serotonin. Serotonin can affect sleep, appetite, temperature, sexual behavior, and pain sensation. Since 5-HTP increases the synthesis of serotonin, it is used for several diseases where serotonin is believed to play an important role including depression, insomnia, obesity, and many other conditions.