With Thanksgiving coming up, we thought it would be fun to tell you about why you get tired after eating a thanksgiving meal. Many people have heard that turkey makes you tired, but that is kind of a myth.
The reason why most people have heard about turkey making you tired is because of an ingredient called Tryptophan. Tryptophan is an essential amino acid that is used to make serotonin, a chemical in the brain that helps make you sleepy (1). In order to get enough tryptophan to make you tired, a person would have to eat approximately 40 pounds of turkey (2). We don’t know about any of you, but none of us can eat 40 pounds of food.
Consuming tryptophan in combination with some of more common food culprits of the holidays, carbohydrates and alcohol, can further increase brain levels of serotonin (3). Those foods can have a effect on how sleepy you get (especially the alcohol), but not because of the serotonin increase.
The primary culprit as to why you get tired after a Thanksgiving meal is simple – your nervous system. Your gut has a group of nerves that goes to it called the Parasympathetic Nervous System (PNS). The PNS is known as the “Rest and Digest” part of the nervous system. When food hits your stomach, the PNS brings more blood to the area to aid with digestion (4). When this occurs, a calming effect happens in your body, your heartbeat slows, and you get sleepy.
So there you have it. You get sleepy not because of turkey, but simply because it is your bodies normal response to eating a ton of food.
1) Human Anatomy & Physiology, 6th Ed. Marieb, Elaine B. Page 416. ©2004
2) Houston Chronicle, “Q&A: Real reason a turkey dinner puts you to sleep”. Berger, Eric. November 23, 2008. © 2008
3) Nutrition Now, 3rd Ed. Brown, Judith E. Section 5-12. ©2002
4) Guyton & Hall Textbook of Medical Physiology, 10th Ed., Guyton MD, Arthur C. and Hall PhD, John E. Page 703. ©2000
Christopher Knapp, D.C.