Now L-Tryptophan Powder supports restful sleep, and positive mood. It is critical for the production of serotonin and melatonin that help support healthy sleep patterns and proper immune system function. L-Tryptophan is an essential amino acid; therefore, it is not synthesized by the body and must be obtained from the diet. Double Strength L-Tryptophan has twice the L-tryptophan (1000 mg per tablet) as in our regular strength product (500 mg per capsule). Recommended Use: Take 1 or 2, 1/4 level teaspoons, 2 to 3 times daily on an empty stomach, with final dose at bedtime, or as directed by a healthcare professional. Store in a cool, dry place after opening.