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Does Eating Turkey Make You Sleepy?
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Does the Tryptophan in Turkey Actually Cause Sleepiness?
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Does Eating Turkey Make You Sleepy?

Written by
Kara Rogers
Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and...
Kara Rogers
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Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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Does the Tryptophan in Turkey Actually Cause Sleepiness?
Does the Tryptophan in Turkey Actually Cause Sleepiness?How chemistry explains tryptophan and debunks the myth that eating turkey (which contains it) induces drowsiness on Thanksgiving.
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Contrary to popular belief, eating turkey itself does not cause drowsiness. The sleepiness that is often felt after a big turkey dinner—such as that enjoyed on Thanksgiving Day in the United States—is more likely due to the consumption of large portions of food, which alters blood flow and triggers the release of neurochemicals and hormones associated with the digestive process.

At the center of the turkey-and-sleep myth is tryptophan, an essential amino acid associated with drowsiness because it serves as a precursor to serotonin and melatonin—neurochemicals that help regulate mood and sleep. The amount of tryptophan in turkey, however, is far too small to cause these effects on its own. In fact, the body absorbs only small amounts of the amino acid from food—far less than what is needed to significantly influence serotonin or melatonin production. Moreover, tryptophan is not unique to turkey; it is also present in chicken, eggs, dairy products, and fish.

The real culprit is overconsumption. Studies in humans and animals have demonstrated that a larger meal, especially one rich in carbohydrates and fats, results in a greater and more prolonged increase in blood flow to the digestive tract compared with a smaller one. While this increase ensures an adequate supply of oxygen and other substances such as hormones needed for processing food, it also redirects blood away from other parts of the body, such as the brain and muscles, which can result in feeling heavy, slow, and tired.

Foods high in carbohydrates and fats may also cause a spike and subsequent crash in blood sugar, as well as the release of fat-related pro-inflammatory proteins known as cytokines, which can contribute to fatigue. These effects are often magnified in people with chronic diseases such as hypertension or diabetes. Add in alcohol, a central nervous system depressant, and it is no wonder that even healthy people become sleepy after devouring a generous spread of classic side dishes surrounding the unmistakable Thanksgiving turkey.

Kara Rogers