California natural l-tryptophan description: healthy sleep patterns usp pharmaceutical grade l-tryptophan is an essential amino acid a component of many plant and animal proteins. Essential amino acids are not synthesized by the body and must be obtained in the diet. It is a precursor from which our brains make serotonin, which is then used to calm you down and make you sleepy. L-tryptophan, in substantial quantities, is a natural sedative. Tryptophan also helps in niacin (b vitamins) production. The l-tryptophan in this product is manufactured and tested for purity according to united states pharmacopeia (usp) standards. Disclaimer these statements have not been evaluated by the fda. These products are not intended to diagnose, treat, cure, or prevent any disease.