Q. Does eating turkey really make you sleepy?
A. Turkey alone will not make you sleepy. It’s true that L-tryptophan, an essential amino acid found in turkey and many other protein foods, can have a sedative effect in some people, says Linda Yerardi, R.D., a diabetes nutrition educator at Mercy Medical Center in Baltimore, Maryland. But its effects are blunted by the presence of other amino acids in turkey, which compete for the same binding sites in the brain for absorption, she notes. “You’d have to take L-tryptophan alone (with no other amino acids present) and on an empty stomach to produce any drowsiness.” Consuming tryptophan-rich foods may cause blood levels of the amino acid to rise, but not enough tryptophan will reach your brain to have a sedative effect.
“Lots of other foods, including ground beef and chicken, contain L-tryptophan, too, and don't have this reputation. Turkey gets a bad rap because of Thanksgiving,” Yerardi continues. “People get sleepy after this meal for a variety of factors, not the L-tryptophan alone. The more likely reason is that it takes a great deal of energy to digest a large meal. A full stomach means that blood is directed away from other bodily functions and systems, including your nervous system, which can make you sleepy.”