It's not the tryptophan in turkey that makes us drowsy on the fourth Thursday in November, according to a video produced by the American Chemical Society.
Tryptophan is an essential amino acid. Our bodies to use it to make serotonin, a brain chemical that promotes feelings of well being and relaxation, which in turn makes melatonin, which helps control our sleep and waking cycles.
But tryptophan levels in turkey are simply too low to cause drowsiness.
So what to blame instead for the holiday lethargy? Carbs! They're all over the Thanksgiving meal. Carbs and overeating. Stuffing ourselves diverts blood from the brain to the digestive system, and that makes us feel tired.
And if you've got some guests who are grousing or fiddling because dinner isn't ready yet, park them in front of a second video from the chemical society, where they'll learn how the pop-up timer in a turkey works, why muffins rise and which antacids work best, among other bits of science.