Posted by: tpsciencefun | November 18, 2009

Does Turkey Make You Tired??

If Thanksgiving dinner makes you tired, you are not alone.  There are scientific explanations for your sleepiness.  Read on…if you’re not too tired!

Oh, and HAPPY THANKSGIVING!!  I am so thankful you all are in my life AND I get to teach you science! 

Here’s your answer:

Tryptophan & Carbohydrate Chemistry

By Anne Marie Helmenstine, Ph.D., Guide

Large Female White TurkeyLarge Female White Turkey

Unless a microwave dinner is your idea of a Thanksgiving feast, you probably have had firsthand experience with the after-dinner fatigue that sets in after the meal. Why do you want a nap? To escape the dishes? Perhaps, but the meal itself plays a big part in the way you feel.

             L-Tryptophan and the Turkey

  • The turkey is often cited as the culprit in afterdinner lethargy, but the truth is that you could omit the bird altogether and still feel the effects of the feast. Turkey does contain L-tryptophan, an essential amino acid with a documented sleep inducing affect.  However, L-tryptophan needs to be taken on an empty stomach and without any other amino acids or protein in order to make you drowsy. It’s worth noting that other foods contain as much or more tryptophan than turkey, including chicken, pork, and cheese.  As with turkey, other amino acids are present in these foods besides tryptophan, so they don’t make you sleepy. 

             L-Tryptophan and Carbohydrates

  • L-tryptophan may be found in turkey and other dietary proteins, but it’s actually acarbohydrate-rich which  increases the level of this amino acid in the brain and leads to sleepiness.  


  • Fats slow down the digestive system, giving Thanksgiving dinner plenty of time to take effect. Fats also take a lot of energy to digest, so the body will redirect blood to your digestive system to tackle the job. Since you have less bloodflow elsewhere, you will feel less energetic after eating a meal rich in fats.  


  • It takes a great deal of energy to digest a large meal. When your stomach is full, blood is directed away from other organ systems, including your nervous system. The result? You will feel the need to snooze after any big meal, particularly if it is high in fats and carbohydrates. 


  • Although many people find the holidays stressful, the most relaxing part of the festivities is likely to be the meal. No matter what you may have been doing throughout the day, Thanksgiving dinner provides an opportunity to sit back and relax — a feeling that can carry over after the meal.

So, why are you sleepy after a big turkey dinner? It’s a combination of the type of food, amount of food, and celebratory atmosphere. Happy Thanksgiving!



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