According to folklore, the tryptophan in turkey makes you feel drowsy and want to nap after Thanksgiving dinner. Here's the reasoning: the body needs tryptophan to make serotonin and melatonin, two brain compounds that help regulate mood and sleep. Tryptophan is an amino acid, or building block of protein, and turkey is high in protein.
But here's where the reasoning falls apart: although turkey contains tryptophan, so do many meats, chicken, tofu, nuts and dairy foods. If tryptophan made us drowsy, so would these other protein sources.
A more likely culprit is eating a bigger-than-usual meal full of carbohydrate-rich foods such as potatoes, rolls and pumpkin pie because carbs increase brain serotonin levels. Other factors are imbibing in a glass or two of wine or other alcoholic drinks and-if you're the cook-getting up earlier than usual to get the turkey in the oven!