What the Science Says

Let’s get the scoop on tryptophan.

There’s always that one fact-spewing relative at the Thanksgiving table who has to announce that turkey, FYI, contains something called tryptophan, which makes you sleepy, and that’s why everyone’s going to pass out while watching the football game later.

Well, not so fast. Turkey does contain tryptophan—an amino acid that influences sleep and mood. What you might not know: You can find similar amounts of tryptophan in other proteins, like chicken and beef (about 350 milligrams for every 115-gram serving). And that’s not all—there are even greater amounts of tryptophan in foods like pork and cheese.

If you eat these foods on the regular and don’t find yourself dozing off on a couch every day, you can already spot the flaw in the logic.

Actually, turkey could help make you drowsy, but only if you eat it on an empty stomach. The sleepy effect of tryptophan loses its potency when combined with other food; it’s not as easily absorbed. A study in American Journal of Clinical Nutrition found a carby breakfast can balance out the influence of tryptophan on the brain—and everyone knows a classic Thanksgiving dinner is loaded with carbs.

But those carbs aren’t exactly innocent here. Large meals high in carbs and protein—not to mention the wine—also give you that must-nap-now feeling. ) In other words, yep, there’s a reason you’re feeling sleepy after your Thanksgiving dinner, but it’s more about the overall size and heaviness of your meal than the bird on your plate.