We’re all familiar with the classic tale — after a big Thanksgiving meal, it’s time for a nap, and usually turkey is to blame. But is it really the turkey’s fault, or is there more to the story? Let’s dive into the science behind this theory to see if turkey is solely responsible for inducing that post-meal drowsiness.
Tryptophan and Turkey
Turkey contains a natural amino acid called tryptophan. Tryptophan is an essential amino acid, meaning our bodies can’t produce it, so we must obtain it through our diet. It plays an important role in protein synthesis and is a precursor to important molecules like serotonin and melatonin. Serotonin, also known as the “feel-good” neurotransmitter, helps regulate mood, appetite and sleep. Melatonin is a hormone that regulates our sleep-wake cycles.
For tryptophan to be converted into serotonin and melatonin, it must first cross the blood-brain barrier. This process can be tricky because tryptophan competes with other amino acids to enter the brain. Carbohydrate consumption can help with this. Insulin released in response to carbs helps clear other amino acids from the bloodstream, making it easier for tryptophan to cross into the brain. However, despite popular belief, eating tryptophan-rich foods like turkey in normal quantities doesn’t cause a significant enough increase in serotonin or melatonin to make you feel sleepy on its own.
Surprisingly, turkey does not contain a significant amount of tryptophan. The amount of tryptophan found in turkey is similar to what you would find in other protein sources including cheese, yogurt, chicken and nuts. Studies show that approximately five grams of tryptophan are needed to improve sleep, which is equal to 5,000 milligrams (mg). One three-ounce serving (roughly the size of a deck of cards) of turkey breast only contains between 180 to 244 mg of tryptophan, which means you would need to eat about 61 to 84 ounces of turkey to get 5,000 mg of tryptophan.
So, What’s Really Making You Sleepy?
If you’ve ever found yourself needing a nap after a big holiday meal, it’s more than likely the overall combination of foods, and not just the turkey. Large meals, especially those high in carbohydrates like stuffing, mashed potatoes and sweet treats, can lead to a spike in blood sugar followed by a crash, which may leave you feeling tired and sluggish. Additionally, when you eat a big meal, your body redirects energy to digesting food, which can contribute to that post-meal drowsiness.
While turkey contains a slight amount of tryptophan, the drowsiness you feel after a meal is usually due to other factors, such as:
Carbohydrates: Foods rich in carbs (like rolls, stuffing, pies and cakes) can cause a spike in insulin, which helps move amino acids into your muscles, leaving more tryptophan in your bloodstream. This could explain why most people feel sleepy after a big, carb-heavy meal.
Overeating: Large meals require more energy for digestion, and this process takes blood away from other parts of your body, including your brain. This redirection of energy can leave you feeling tired and drowsy.
Alcohol: If your meal includes a cocktail or a glass of wine, these beverages may contribute to feelings of drowsiness by depressing the central nervous system.
How To Prevent Drowsiness After a Big Meal
Preventing drowsiness after a big meal starts with portion control. Eating smaller, more balanced meals can help reduce the strain on your digestive system and prevent the post-meal crash often associated with overindulgence. By eating a moderate portion and focusing on nutrient-dense foods — such as lean proteins, vegetables and whole grains — you can avoid overwhelming your system. It’s also helpful to slow down and practice mindfulness while eating, giving your body time to process the meal and signal when you’re full.
Another way to prevent drowsiness is to be mindful of your carbohydrate intake. While carbohydrates are an important energy source, consuming an excessive amount of refined carbs and sugary desserts, can lead to a spike in blood sugar followed by a sudden drop, making you feel tired. Opt for complex carbohydrates, such as whole grains and vegetables, which are digested more slowly and provide a steady source of energy.
Staying hydrated and moving around after a meal can also help counteract the post-meal drowsiness by promoting digestion and keeping your energy levels steady.
The Bottom Line: While turkey does contain tryptophan, the amount isn’t significant enough to make you sleepy on its own. The real cause of post-meal drowsiness is often a combination of factors, including the size of the meal, the variety of foods consumed and lifestyle factors such as alcohol consumption. To help prevent drowsiness after a big meal, practice portion control, balance your plate with lean proteins and complex carbs, and stay active afterward to support digestion.