When we’re lolling on the couch after Thanksgiving dinner, we all point the finger at turkey for inducing our food stupor. The L-tryptophan in turkey is broken down in the body to produce serotonin, a chemical that makes us feel relaxed and is used to make melatonin, a sleep hormone. That’s true. But turkey gets a bad rap; it doesn’t have any more tryptophan in it than a lot of other foods, like cheese, eggs and fish, and has even less than its clucky kin, chicken. The reason we get comatose after giving thanks isn’t just the bird. We’re also gorging on tons of carbohydrates, which significantly boost serotonin on their own. What’s more, combining tryptophan with carbs increases how much tryptophan can make it to the brain. Taken all together, that’s a recipe for naptime.