To avoid that long, Thanksgiving nap, follow this piece of fowl advice: Gobble down more turkey.

Grandma’s secret turkey recipe may not be the cause of those seemingly inevitable naps after dinner. It may be because of her mashed potatoes, stuffing or homemade rolls. Tryptophan, an amino acid found in turkey proteins, has been thought to increase a person’s feeling of sleepiness because of it increase the production of serotonin.

“I’m not sure why turkey is picked on. All proteins contain some levels of tryptophan,” said Paul Flakoll, professor of food science and human nutrition and director of the Center for Designing Foods for Nutrition.

Sherri Rosenblatt, spokeswoman for the National Turkey Federation, said research shows swiss cheese, milk and pork all contain higher levels of tryptophan than turkey.

“When [tryptophan] gets into the brain, it changes the balance of amino acids of the brain and can cause what’s called central fatigue,” Flakoll said. “The way that happens is other amino acids are lessened in the brain and a production of a chemical called serotonin, which makes you sleepy, can increase. Whether it’s higher because of turkey, I’m not sure if it’s really been tested.”

Research also shows eating a protein-rich meal, even if it contains a large amount of tryptophan, may not increase the amount of tryptophan in the blood to affect serotonin levels. Carbohydrate-rich meals, however, increase the amount of tryptophan in the blood, making people feel sluggish.

“The reality is probably based on the high carbs we eat, the atmosphere of having friends and family around and the few cocktails we might have that makes us more relaxed and comfortable,” Rosenblatt said.

The effects of eating turkey are opposite of the normal, preconceived ideas, she said.

Turkey is a good source of protein and, according to an article from the National Turkey Federation titled “Let turkey improve your mood – naturally,” protein bolsters the production of certain amino acids that occur naturally in the brain that affect some aspects of a person’s mental outlook. For example, production of dopamine and norepinephrine both increase mental alertness and concentration, and noradrenaline eases depression.

Flakoll said meals, in general, produce similar effects.

“There has been work showing there is some post-meal sleepiness, but we feel comfortable after a meal, so the feeling of sleepiness sort of fits into the rest,” he said.

Anne Marie Bonness, spokeswoman for ConAgra Foods Inc., the company that packages Butterball turkeys, said as far as she knows, officials have never considered labeling turkeys to warn consumers not to operate a vehicle after eating.