A typical Thanksgiving in many families across the country involves scarfing down some turkey meat before crawling over to the couch for an afternoon nap. And no matter where you are in the US, it isn’t uncommon to hear, “Mom, I need to nap. I’m full of turkey!” But is there validity behind this statement? Does turkey really make you sleepy, or is it a myth we’ve all accepted and use as an excuse to get those extra zzz’s in?
Here’s what you should know.
Simon Young, Ph.D, tells Psychology Today, “It’s a complete myth.”
Perhaps unsurprisingly, there are many misconceptions about tryptophan in the press. The fact of the matter is that the amino acid ultimately doesn’t have much of an effect unless a) it’s taken on an empty stomach or b) we ingest way more than what we get out of our Thanksgiving dinners. Furthermore, a number of meats carry similar amounts of tryptophan and don’t cause drowsiness. If it were taken alone, tryptophan could increase brain serotonin and cause sleepiness, but it merely doesn’t exist in those quantities in a Thanksgiving meal.
Tryptophan is a key ingredient in making serotonin, which promotes calm, relaxation, and sleepiness. Psychology Today writes, “If anything, eating turkey lowers tryptophan. That’s because tryptophan uses the same means of transport into the brain as other amino acids, and has to compete against them to cross the blood-brain barrier.”
So what’s really going on? Why the need to snooze? What’s most likely happening is that your body is using a lot of energy to digest the fats its just taken in. And between turkey skin and the pie you’ll likely consume, the energy being used to digest things is making you sleepy. According to Mental Floss, the average Thanksgiving meal contains 3,000 calories and 229 grams of fat– your body has to kick into overdrive to process all that food, which reduces your overall energy and leaves you craving a nap.
Neuropharmacologist Richard Wurtman of the Massachusetts Institute of Technology’s Department of Brain and Cognitive Sciences in Cambridge, Mass, tells Scientific American, “Paradoxically, what probably makes people sleepy after Thanksgiving dinner is…dessert. Eating carbohydrates increases brain serotonin in spite of the fact that there is no tryptophan in carbohydrates.”
Biologist H. Craig Heller of Stanford University provides an alternative theory, stating stating, “Studies have indicated that stretching of the small intestine induces sleepiness and a protein–fat loading of the stomach induces sleepiness… and, more blood going to the gastrointestinal tract means less going elsewhere.”
This isn’t to say that tryptophan doesn’t come with other perks. According to an interview with Morton Walker, DPM, tryptophan works to relieve “depression, common anxiety, irritable bowels, inflammation of the colon, hormonal imbalances, particularly estrogen/progesterone imbalances, premenstrual symptoms, unhealthy cravings for alcohol and carbohydrates, plus other common mental and emotional difficulties.” It has, perhaps unsurprisingly, proven helpful in treating insomnia, too. So, when you take a seat this week and dive into some turkey, keep in mind that while it may not make you sleepy, it could be relieving other stresses that come with the holiday.