From the Manufacturer:
L-Tryptophan has helped millions of people find a deeper more relaxing sleep, and help to reduce stress and physical pain.
L-Tryptophan is the precursor to Serotonin, a neurotransmitter in the brain, which is deficient in depression and naturally enhances sleep. Each capsule of Pure L-Tryptophan has 500 mg. of the highest quality USP Pharmaceutical Pure Grade L-Tryptophan available for professional use.