Ever wonder why you feel like taking a nap after that Thanksgiving dinner? It’s because of the amino acid, Tryptophan. Tryptophan helps produce Niacin and Niacin then produces Serotonin. Experts now say that Tryptophan is only produced on an empty stomach. So maybe it’s not just the turkey that makes you want to take a nap after that great dinner, It might just be all those yummy carbs settling in your tummy.