The chemical in turkey that is often blamed for making people sleepy is tryptophan, an essential amino acid found in various foods, including turkey. Tryptophan can influence mood and sleep as it contributes to serotonin and melatonin production. However, eating foods with tryptophan in addition to a large number of carbohydrates leads to sleepiness, not tryptophan alone. Carbohydrates come from the other typical foods at the Thanksgiving table, such as bread, potatoes, peas, corn, sugary drinks, and desserts. Therefore, it is not just the turkey that makes people sleepy after Thanksgiving dinner, but rather the combination of tryptophan and carbohydrates from other foods.