Is Tryptophan's Soporific Effect the Baloney We Serve With Our Turkey?
It goes like this: tryptophan, an amino acid, helps create seratonin. Among other things, seratonin also helps regulate your sleep cycle, which may be why folks have been perpetuating the tryptophan lie for so many years. While the substance does exist in turkey, it's hardly enough to cause the immediate drowsiness we associate with the holiday meal.
For that, we must blame all the other things we're stuffing into our mouth holes, like mounds of mashed potatoes, tubs of butter, wagon loads of rolls and trays of pies. So there you have it: turkey makes you sleepy but only because you're eating it with 3,508 calories of other equally coma-inducing foods, you glutton. Pass the gravy, please.
Tryptophan was coined in 1890. According to the Online Etymological Dictionary, the word was formed by combining trypsin, "the name for the chief digestive enzyme of pancreatic juice" with phantasm, meaning "to appear." Given that it makes you sound like you're wearing a white lab coat every time it comes out of your mouth, the myth-tophan is likely to stick around for many Thanksgivings to come.