Fact or fiction: Does turkey tryptophan really make you tired?

Thanksgiving is right around the corner. All the signs are there: the trees are bare, there’s a chill in the air and grocery lists are as long as the crowded checkout lines in the food stores. Turkeys are flying off the shelves -- well, not literally -- frozen or fresh, that is. It’s time to get out grandma’s china. It’s time for family, friends, too much turkey and afternoon naps.

So is it true that naps and turkey go together? It is commonly said that eating too much of it causes drowsiness due to the high levels of tryptophan found in the meat. However, according to Leah Devlin, division head of science and engineering and interim assistant dean of Academic Affairs at Penn State Abington, the "I-can’t-do-the-dishes-because-I’m-too-tired" excuse is more myth than truth.

"Tryptophan is an essential amino acid found in many foods, including turkey," said Devlin. "It’s a precursor to forming the neurotransmitter serotonin which has a sedating effect on the brain."

But -- and this is a big but -- "what is not true is that the levels of tryptophan one eats in turkey are enough to cause drowsiness," Devlin said. "The primary culprit of post-Thanksgiving meal sleepiness is simply over-eating, which causes a large shunting of blood toward the digestive tract and away from the brain. This is compounded by a release of insulin from the pancreas that moves the carbohydrates (potatoes, sweet potatoes, rolls, etc.) away from the digestive tract and into storage sites in various body tissues. Insulin can cause slight sleepiness."

"If you want to stay awake for the entire football game or be perky while doing the dishes, eat a moderate amount of food, high in turkey (protein) and vegetables and avoid the carbs."

So when that menacing mountain of Thanksgiving dishes looms, dishwashers unite. Get plenty of dish towels ready because there’s no longer a turkey-related “I’m-too-tired-to-do-the-dishes” excuse.