Dietary supplement. Mood, relaxation, sleep. The essential amino acid L-Tryptophan helps support relaxation, restful sleep, and feeling better. It plays a part in the synthesis of both melatonin and serotonin, hormones involved with mood and stress response. L-Tryptophan also supports immune functions because it is the body’s precursor to the kynurenines that regulate immunity. If needed, L-Tryptophan converts to niacin in the body, which supports circulation, a healthy nervous system, the metabolism of food, and the production of hydrochloric acid for the digestive system. Source Naturals L-Tryptophan is extremely pure and is regularly tested to ensure the highest standards of quality. (These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.) Hypoallergenic: Contains no yeast, dairy, egg, starch, salt, preservatives, or artificial color, flavor or fragrance.