Turkey does have the makings of a natural sedative in it, an amino acid called tryptophan. Tryptophan is an essential amino acid, meaning that the body can’t manufacture it. The body has to get tryptophan and other essential amino acids from food. Tryptophan helps the body produce the B-vitamin niacin, which, in turn, helps the body produce serotonin, a remarkable chemical that acts as a calming agent in the brain and plays a key role in sleep. So you might think that if you eat a lot of turkey, your body would produce more serotonin and you would feel calm and want a nap.
That was the conclusion that led many people to begin taking a dietary supplement of tryptophan in the 1980s as a way to treat insomnia, but the U.S. Food and Drug Administration banned tryptophan supplements in 1990 because of an outbreak of eosinophilia-myalgia, a syndrome that causes muscle pain and even death. The FDA said contaminated tryptophan supplements caused the outbreak. However, it is now believed that the illness was caused by contaminants in the factory in Japan that made the supplements and they are now once again available in the U.S. [source: Miller].
Nutritionists and other experts say that the tryptophan in turkey probably won’t trigger the body to produce more serotonin because tryptophan works best on an empty stomach. The tryptophan in a Thanksgiving turkey has to vie with all the other amino acids that the body is trying to use. So only part of the tryptophan makes it to the brain to help produce serotonin. Tryptophan may also be found in cheese, milk, chicken and nuts.
In the next section, we’ll look at what may be the real reason why so many of us just want to take a nap on Thanksgiving.
Thanksgiving Dinner and Trytophan
Most likely, it’s the whole traditional Thanksgiving meal that produces that after-dinner lethargy. The meal is quite often heavy and high in carbohydrates — from mashed potatoes, to bread, stuffing and pie — and your body is working hard to digest that food. After all, the average Thanksgiving meal contains 3,000 calories and 150 grams of fat [source: Snider]. Also, if you drink alcohol with your dinner, you’ll likely feel its sedative effect, too.
The amount of tryptophan in two servings of turkey is about 410 milligrams, while a tryptophan supplement dose (to help with sleep) would be 5 grams or 20 servings of turkey [source: Healthline].
So, don’t blame the turkey for your after-Thanksgiving lethargy! It’s probably a combination of overeating, alcohol and the earlier darkness at this time of year. And if you’re feeling sleepy, there’s nothing wrong with taking a post-Thanksgiving dinner nap!
Originally Published: Nov 7, 2007
Lots More Information
More Great Links
- Farley, Dixie. “Dietary Supplements: Making Sure Hype Doesn’t Overwhelm Science.” U.S. Food and Drug Administration. http://www.fda.gov/bbs/topics/CONSUMER/CON00259.html
- Healthline. “Let’s Talk Turkey: Does It Make You Sleepy?” (Nov. 22, 2022) https://www.healthline.com/health/why-turkey-make-you-sleepy#other-contributors
- Miller, Kelli, “L-tryptophan.” WebMD. Sept. 24, 2021 (Nov. 22, 2022) https://www.webmd.com/vitamins-and-supplements/l-tryptophan-uses-and-risks
- Snider, Mike. “Eating a typical Thanksgiving dinner? You’re downing 3,000 calories, and a stick of butter.” Nov, 22, 2021 (Nov. 22, 2022) https://www.usatoday.com/story/news/health/2021/11/22/2021-calories-thanksgiving-dinner/6386545001/
- United States Census Bureau. Nov. 23, 2006. http://www.census.gov/Press-Release/www/releases/archivesfacts_for_features_special_editions/007643.html