Why Thanksgiving Dinner Makes You Sleepy:

Every Thanksgiving, even the most caffeinated scientist finds themselves slipping into an unscheduled nap on the couch, wondering if the turkey’s tryptophan is to blame. While it’s tempting to assign responsibility to the bird, the truth is more nuanced—and less feathered. Turkey does contain tryptophan, the amino acid precursor to serotonin and melatonin, but no more than your average chicken sandwich. The real culprit is the mountain of carbohydrates beside it: stuffing, mashed potatoes, rolls, and pie. This carb surge triggers insulin release, which helps tryptophan sneak past the blood-brain barrier, ultimately boosting serotonin and melatonin levels. In short, it’s not the turkey’s fault—it’s the company it keeps on your plate.

Physiologically, your body is also staging a quiet revolt. After consuming a caloric intake rivaling a small mammal’s daily requirement, blood flow is rerouted toward your digestive system in an elegant display of postprandial hyperemia. Translation: your brain gets a bit less blood, and your stomach gets a party. Hormones like cholecystokinin (CCK) and peptide YY (PYY) then chime in to say, “Congratulations, you’re full—please stop moving.” Add in the fact that most Thanksgiving dishes are rich in fat and sugar, and your metabolic machinery decides it’s an excellent time to slow things down—preferably horizontal on the couch, possibly mid-football game.

And then there’s the human factor. Between the travel, the cooking marathons, and the subtle stress of explaining your research to relatives for the fifth time, your nervous system is already primed for collapse. Top it off with a glass (or three) of wine, and the hypothalamus happily calls it a day. So yes, the infamous “food coma” is not mere gluttony but a finely orchestrated symphony of biochemistry, blood flow, and social exhaustion. If nothing else, consider it a physiological reminder that sometimes, even our bodies believe in the scientific principle of rest after a big experiment.