It may be my favorite medical myth, and it’s totally appropriate for Thanksgiving. Please enjoy this chapter from my book:
Myth: Eating Turkey Makes You Sleepy
While not everyone stoops to the level of Seinfeld’s Jerry and George, who used tryptophan in turkey to lull a girl asleep so that they could play with her toys, the supposed sleep-inducing effects of tryptophan in turkey are commonly recounted at American Thanksgiving feasts and in the popular media around the holidays.
Scientific evidence does support a connection between tryptophan and sleep. L-tryptophan has been marketed as a dietary supplement to aid with sleep. Tryptophan also may have an effect on the immune system, with possible benefits for autoimmune disorders such as multiple sclerosis.
The truth is, turkey is not to blame for your sleepiness. Chicken and ground beef contain almost the same amount of tryptophan as turkey — about 350 milligrams per 4 ounce serving. While you might have heard someone claim that turkey made them drowsy, you have probably never heard someone say that chicken, ground beef, or any other meat made them sleepy. Swiss cheese and pork actually contain more tryptophan per gram than turkey, and yet the American classic, a ham and cheese sandwich, somehow escapes blame.
The amount of tryptophan in a single 4 ounce serving of turkey (350 milligrams) is also lower than the amount typically used to induce sleep. The recommendations for tryptophan supplements to help you sleep are 500 to 1000 milligrams. Many scientists also think the limited amount of tryptophan in turkey would be offset by the fact that it is generally eaten in combination with other foods and not on an empty stomach. While one clinical trial found comparable results for tryptophan from a food protein-source and pharmaceutical grade tryptophan, this study also used an extremely rich source of tryptophan, deoiled gourd seeds, which have twice the tryptophan content of turkey. In this trial, and in general use of supplements, tryptophan is taken on an empty stomach to aid absorption. Although we did not locate any experimental evidence to support this claim, many believe that the presence of other proteins and food in the stomach during the feasts generally associated with turkey consumption would limit the absorption of the tryptophan in the turkey.
There are other elements of the holiday feasts that can induce drowsiness. Large meals have been shown to cause sleepiness regardless of what is eaten because the body increases blood flow to the stomach, and decreases blood flow and oxygenation to the brain. Meals both high in proteins or in carbohydrates may cause drowsiness. And don’t forget about the booze. One or two glasses of wine, especially for people who only drink occasionally, can increase drowsiness.
Have a happy Thanksgiving, everyone. Stop blaming the turkey for your sleepiness.
DON’T SWALLOW YOUR GUM! by Aaron Carroll, MD and Rachel Vreeman, MD copyright © 2009 by the author and reprinted with permission from St. Martin’s Griffin, an imprint of St. Martin’s Press, LLC