“Eating turkey makes you sleepy.”

That heavy feeling of drowsiness after a big holiday meal is often blamed on the star of the show: the turkey. Many believe that this poultry possesses a unique power to usher in an irresistible desire for a nap, a common misconception that has become almost as traditional as the meal itself. This idea likely stems from the fact that turkey does contain tryptophan, an amino acid that plays a role in the production of serotonin and melatonin, both of which are linked to relaxation and sleep.

While it's true that tryptophan is a precursor to these sleep-inducing chemicals, the amount found in a typical serving of turkey isn't significantly higher than in many other common foods, like chicken, cheese, or even nuts. For tryptophan to effectively cross the blood-brain barrier and have a noticeable effect on sleepiness, it needs to be consumed in much larger quantities and ideally with a low-protein, high-carbohydrate meal. A large portion of turkey, however, is rich in other amino acids that compete with tryptophan for absorption, limiting its impact.

The actual culprits behind that post-feast slump are far more complex and usually involve the overall dining experience. Consuming a large volume of food, particularly one rich in carbohydrates and fats, requires a significant amount of energy for digestion, diverting blood flow to the digestive system. Additionally, alcoholic beverages, often enjoyed during festive meals, are well-known depressants that can contribute to feelings of fatigue. The combination of these factors, rather than the tryptophan in turkey alone, is what truly makes many people feel ready for a nap after a grand meal.