(SW1502)L-Tryptophan 500 mg 60 CapsHelps support healthy serotonin levels, restful sleep and regulates body's circadian rhythm Helps combat jet lag Important amino acid that must be obtained from diet or supplements Looking for effective sleep support? Swanson L Tryptophan offers 500 mg of L tryptophan per capsule to help support healthy serotonin levels and provide restful sleep. L tryptophan, an essential amino acid, has to be obtained in the diet or in supplement form. Extensive lot