Didja know that chicken, beef and lamb, as well as oats, all have slightly more tryptophan than does turkey? Sesame and pumpkin seeds have twice the amount, codfish has 3 times the amount, and egg whites have 4 times the amount.
When you get sleepy after stuffing yourself after a big turkey dinner, it's not because of the tryptophan, it's because when you over eat, blood is diverted from the brain to the stomach, which makes you sleepy.
Just a little FYI.