“Eating turkey makes you especially sleepy because of tryptophan”

Many people associate the feeling of post-holiday meal drowsiness with the turkey they've just consumed, attributing it to an amino acid called tryptophan. This widespread belief likely gained traction through popular media in the 1970s, with articles and even comic strips linking turkey to sleep-inducing tryptophan, sometimes without fully understanding the science behind food composition and metabolic processes. The myth persists because the experience of feeling tired after a large meal, often featuring turkey, is a very real phenomenon for many.

While it is true that turkey contains tryptophan, an essential amino acid that the body uses to produce serotonin and melatonin—both neurotransmitters involved in regulating sleep and mood—turkey does not contain an exceptionally high amount of it. In fact, other common foods like chicken, beef, cheese, nuts, and even oats have comparable or sometimes higher levels of tryptophan. When you eat turkey as part of a protein-rich meal, tryptophan must compete with many other amino acids to cross the blood-brain barrier, significantly reducing its individual impact on your brain chemistry.

The real culprits behind that sleepy sensation after a big meal are typically a combination of factors. Overeating, especially large quantities of carbohydrates found in side dishes like stuffing, mashed potatoes, and desserts, leads to a surge in insulin. This insulin spike can facilitate the entry of tryptophan into the brain, but it's the overall metabolic response to a heavy, carb-laden meal that truly contributes to drowsiness. Additionally, alcohol consumption and the general relaxation and reduced physical activity often associated with holiday gatherings further amplify feelings of lethargy. So, while turkey is a part of the feast, it's the entire meal and its effects on your digestive system and blood sugar, rather than the turkey's tryptophan alone, that are responsible for the post-meal slump.