Skip to main content

Why Does Turkey Make You Tired?

Thanksgiving and Christmas means enjoying a delicious meal with turkey and other seasonal foods. But in this season, there is also a common question: Why do you get tired after eating turkey? Does turkey really make you tired, or is something else going on?

The Theory Behind It: L-Tryptophan

When most people talk about turkey making you tired, they blame L-Tryptophan. This is an amino acid that is found in abundance in turkey. Amino acids are building blocks of proteins in our bodies.

When you eat L-Tryptophan in turkey or other food, the amino acid moves from the digestive system to your brain via the blood. When in your brain, the L-Tryptophan becomes serotonin, a chemical that helps us sleep and stay calm.

Why L-Tryptophan Doesn’t Make You Tired

Given the fact that L-Tryptophan turns into serotonin, it seems like a logical cause of sleepiness on Thanksgiving or after eating turkey on any occasion. But that’s not the case even though serotonin typically calms you down.

In reality, L-Tryptophan will make you tired right after you eat it, only if you don’t eat any other amino acids. And that’s not the case when you eat turkey, which contains numerous other amino acids.

Other amino acids prevent L-Tryptophan from making you sleepy because of the fact that all the amino acids need to use the same transport proteins to cross the blood-brain barrier. Because L-Tryptophan is one of the least-abundant amino acids in turkey, it has tough competition. The other amino acids are much more likely to make it over the blood-brain barrier, so you won’t get the serotonin-producing effects of L-Tryptophan.

If Turkey Doesn’t Make You Tired, What Does?

While scientists say that turkey doesn’t make you tired after eating Thanksgiving dinner, this doesn’t mean that you just imagine the feelings of lethargy and sleepiness.

Blood Flow

Most experts agree that blood flow is the real reason you get tired after Thanksgiving dinner or any other large meal. Your stomach needs additional blood flow to help it digest a hefty meal. This means less blood is flowing to your brain, which results in a feeling of tiredness.


Blood flow isn’t the only reason you get tired after a large meal. Carbohydrates, especially those in dessert, are another potential culprit. Carbohydrates can increase serotonin levels in your brain as well. Considering the bread you eat with the main meal and the carbohydrates in your dessert, you likely eat plenty of carbs at Thanksgiving.

The Parasympathetic Nervous System

Your parasympathetic nervous system can also play a role. It goes by the motto “rest and digest.” Simply put, it conserves your energy by reducing your blood pressure and heart rate, making you sleepy. This system also increases gastric action and salivation so you can digest your large meal.

Your Drink

Your sleepiness after a large meal with turkey may also be influenced by your beverage. If you have spirits, like wine, beer, or champagne, you will likely feel tired after drinking these downers.


For years, many people believed that the L-Tryptophan in turkey is the reason we get tired after a Thanksgiving meal. But the turkey isn’t to blame at all. You get sleepy after a large meal due to your blood flowing to your digestive system, your parasympathetic nervous system “resting and digesting,” the carbs you consumed, and your alcoholic beverages.