The Tryptophan in Turkey: Understanding its Role in Post-Meal Sleepiness

The phenomenon of feeling sleepy after indulging in a turkey feast, particularly during festive occasions like Thanksgiving, has often been attributed to the presence of tryptophan in turkey. However, the science behind this common claim is more complex than it might seem. This article will explore the intricacies of tryptophan, how it interacts with our bodies, and why it might not be the sole reason for your post-turkey dinner slump.

What is Tryptophan?

Tryptophan is one of the essential amino acids, which means it’s a building block of protein that the body cannot synthesize on its own and must be obtained through diet. It is present in various protein-rich foods, including turkey, chicken, milk, cheese, yogurt, fish, and eggs.

Tryptophan and Sleep: The Connection

The reason why tryptophan is so closely linked with sleepiness lies in its role in the body’s production of serotonin, a neurotransmitter that contributes to feelings of well-being and happiness. Serotonin is also a precursor to the hormone melatonin, which regulates sleep-wake cycles. Tryptophan, upon consumption, is converted into serotonin, which in turn can be converted into melatonin. Elevated levels of melatonin signal to the body that it’s time to sleep, which could explain the association between tryptophan and sleepiness.

The Turkey Myth

The leap from tryptophan to turkey to sleepiness seems logical, but it’s not entirely accurate. Turkey does contain tryptophan, but no more than other common meats — in fact, gram for gram, turkey isn’t significantly higher in tryptophan than chicken or beef. Additionally, tryptophan competes with other amino acids to cross the blood-brain barrier, and when you consume it as part of a protein-rich meal, it’s less likely that significant amounts of tryptophan will make it into the brain to produce that sedative effect.

So, Why Do We Get Sleepy?

If the tryptophan in turkey isn’t solely to blame for the sleepiness, what is? The answer likely lies in the overall context of how we consume turkey, especially during holidays. These meals are often large and rich, comprising carbohydrates, fats, and alcohol — all of which contribute to a post-meal decline in energy.

  • Carbohydrates: Foods high in carbohydrates stimulate the release of insulin, which in turn triggers the uptake of amino acids to the muscle, except for tryptophan, which remains in the bloodstream at higher concentrations. This relative increase in tryptophan can lead to more serotonin production.
  • Fats: Fat-laden foods take longer to digest, directing more blood to the digestive system and away from other systems, leading to a feeling of lethargy.
  • Alcohol: If alcohol is consumed, its sedative properties can add to the feeling of drowsiness.
  • The Size of the Meal: Overeating can trigger the body’s parasympathetic nervous system, which can cause feelings of tiredness as the body focuses on digesting the large amount of food.

The Role of Other Foods

Other foods consumed during a typical turkey feast, such as potatoes, stuffing, and pies, also play a role in the increased production of serotonin and melatonin, leading to that desire for a post-meal nap. Additionally, the presence of other essential amino acids in these foods can amplify the effect.

The Psychological Factor

There’s also a psychological component to consider. During holidays, people tend to relax more, and the atmosphere is generally conducive to resting. This relaxation, combined with the comforting presence of family and friends, can also lead to a natural feeling of sleepiness.

What About Supplements?

Given the connection between tryptophan and serotonin, tryptophan supplements have been studied for their potential to improve mood and sleep. While some studies suggest benefits, the use of tryptophan as a supplement should be approached with caution and ideally under the guidance of a healthcare provider.


The post-turkey sleepiness is likely a combination of factors, including the type of food eaten, the quantity consumed, the presence of alcohol, and the overall relaxing environment. While tryptophan does play a role in sleep regulation, it’s not the direct “sleep-inducing” substance in turkey as often thought. Understanding the broader dietary context and the body’s complex digestive and neurological responses helps demystify why we feel sleepy after a big turkey meal.

In conclusion, while tryptophan in turkey contributes to the body’s natural sleep-wake cycle, it doesn’t act alone. The entire feast, along with the environment, works together to create the perfect storm for a nap. So next time you reach for that second helping of turkey, remember that it’s not just the bird that might be nudging you towards slumber—it’s the sum of the parts, from the side dishes to the relaxed atmosphere, that makes post-turkey drowsiness a common occurrence during holiday gatherings. While turkey may not be the sole culprit, it certainly plays a role in the overall experience.

So, as you enjoy your next turkey dinner, savor the delicious flavors and the joy of spending time with loved ones. And if you find yourself feeling a bit sleepy afterward, know that it’s a natural response to a hearty and satisfying meal, with tryptophan playing just one part in the delightful post-feast tradition.

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