Myth: Eating turkey makes you sleepy

In fact, scientists told National Geographic News the substance could possibly aid in the treatment of depression and multiple sclerosis.

Purified tryptophan is a mild sleep-inducing agent and that probably led to the idea that foods containing heavy doses of the chemical cause drowsiness.

But tryptophan can't function well as part of a meal.

"Tryptophan is taken to the brain by an active transport system shared by a number of other amino acids and there's competition among them -- like a crowd of people trying to get through a revolving door," Simon Young, a neurochemist at McGill University in Montreal, Canada, told National Geographic News.

He said consuming tryptophan-rich foods may cause blood levels of the amino acid to rise, but not enough tryptophan will reach one's brain to have a sedative affect.

And, scientists told NGN, turkey isn't even unusually high in tryptophan. Many other foods, such as beef or soybeans, have higher concentrations.

Copyright 2005 by United Press International