5-HTP is a drug-free and naturally occurring plant-derived amino acid that participates in the body’s synthesis of serotonin. Serotonin can affect sleep, appetite, diet, temperature and sexual behavior; it is the chemical messenger that plays a key role in controlling appetite, insomnia and enhancing mood. In fact, 5-HTP is the direct precursor to this neurotransmitter. It works in the brain and central nervous system and helps in increasing serotonin’s production. It has also been known to help provide a more positive outlook and promotes relaxation and calmness.