Mood-Altering Tryptophan: Some Foods That Will Help Regulate Your Serotonin Levels Through Tryptophan Intake Tryptophan used to have a bad rep. The amino acid found in turkey and other foods was thought to be the major cause of sleepiness on the U.S.’s annual turkey day. Thanksgiving would roll around and all people could talk about was how turkey contains so much tryptophan that your Uncle Kevin was perfectly justified in falling asleep on the couch after his third helping.… Read the rest