CNN
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Do you believe in holiday food comas?
Lots of people do. A mainstay on the dinner table this time of year, turkey contains tryptophan, which is widely thought to be responsible for uncontrollable yawning and sudden naps common after big family celebrations.
“Tryptophan is an essential amino acid needed to make serotonin, a hormone that performs many functions in our body, including mood balance and sleep,” said sleep specialist Dr. Raj Dasgupta, associate professor of clinical medicine at the University of Southern California. Keck School of Medicine.
“The byproduct of the process of turning tryptophan into serotonin is melatonin, another hormone that regulates our sleep cycle,” he said. “Our bodies don’t naturally produce tryptophan, so we have to get it through the foods we eat.”
However, many foods other than turkey contain tryptophan, including cheese, chicken, egg whites, fish, milk, peanuts, pumpkin seeds, sesame seeds, soybeans and sunflower seeds. according to the National Library of Medicine.
Serotonin is one of the “feel good” hormones, which can calm and relax the body. However, we don’t consume enough turkey during a holiday assortment — even if we come back for seconds — to create the amount of serotonin needed to fall asleep, said Steven Malin, associate professor in the department of kinesiology and health at Rutgers University in New Jersey.
To get the amount of tryptophan needed to induce a food coma, he said, we would need to eat about 8 pounds of turkey meat, or about half of a typical bird meant to serve a crowd. The United States Department of Agriculture recommends planning a pound of turkey meat per person when preparing a dinner party.
“Turkey tryptophan is unlikely to enter the brain and produce enough serotonin to put us to sleep,” Malin said.
So you can’t blame the gobbler on your table alone for your sudden drowsiness, said sleep specialist Kristen Knutson, associate professor of neurology and preventive medicine at Northwestern University’s Feinberg School of Medicine.
“Turkey doesn’t really make us sleepy,” Knutson said. “If we feel sleepy after a big meal, it’s probably because we didn’t get enough sleep in the days leading up to the big event and were finally able to relax after dinner was over.”
Overeating in general is also a major culprit for feeling tired after eating, Dasgupta said.
“Remember all the delicious side dishes surrounding the center piece of turkey, like sweet potato pie, casseroles, and delicious desserts,” he said. “These tasty dishes contain a high amount of carbohydrates which also contribute to drowsiness after meals.”
Another reason you feel sleepy after a meal is a change in blood flow from your head to your digestive system.
“Eating a large holiday dinner causes increased blood flow to the stomach to help digest the meal, which leads to decreased blood flow to the brain, making you feel tired and ready for bed,” says Dasgupta.
And don’t forget the impact of alcohol consumption during the holidays, either. Many meals served at this time of year are washed down with wine, cocktails and champagne. And then there’s the ubiquitous beer (or two or three) that often accompanies afternoon ball games.
“Let’s be honest, it’s the holidays and there may be family stress or travel fatigue, so maybe you drank more than your usual amount,” Dasgupta said. “Alcohol slows down your brain and relaxes your muscles, so after a few drinks you’ll probably feel sleepy.”