Snopes: Does turkey make you especially sleepy?

Urban Legends Reference Pages: The Big Sleep:

Claim: Eating turkey makes people especially drowsy.

Status: False.

From Geek Press:

The most likely excuse for drowsiness? Oh, I don't know. It's a mystery. Could have something to do with the 6 pounds of protein and carbs sitting in your belly, and the fact that your body has to rush all available blood to the region to deal with the holiday wad. Add some wine to the mix, and it's a miracle you're not face down in the yams before the pie comes.

As for me, I'm almost face down on the keyboard.