Why am I always so sleepy after eating a Thanksgiving dinner? I’ve heard it is because turkey has a substance that makes you sleepy. Is that true?
Turkey contains a small amount of the amino acid tryptophan, the substance often cited for the cause of sleepiness. In large amounts, tryptophan would make a person sleepy but turkey doesn’t contain that amount—even eggs contain more. What actually makes you lethargic after eating a big Thanksgiving dinner is the amount of food and the amount of carbohydrates that are often eaten during the meal. Most people eat potatoes, bread, stuffing, cranberries, pie, and cookies. All of these foods are carbohydrates and carbohydrates lead to the production of serotonin, a hormone that does make a person sleepy. Also, people often consume larger amounts of alcohol with the meal. Alcohol is a depressant which can also lead to a fatigued or sleepy feeling. Even if people eat a more balanced meal between the macronutrients, most people consume well over 2000 calories at one sitting which places a large demand on the digestive system. When large amounts of blood are diverted to digestive functions, other areas of the body are left without resources so the body goes into a rest mode—often referred to as the body’s tendency to “rest and digest”.