Meat, not turkey, should make you just as tired

NPR - A Myth Examined: Can Turkey Make You Tired?

The conventional wisdom on turkey is that the tryptophan in it makes you sleepy. It does, but just about the same levels of tryptophan (an amino-acid) are in almost all meats and other proteins like nuts, tofu and dairy. The alternate theory for sleepiness on thanksgiving is over-eating, which also makes people sluggish. Interestingly, higher doses of tryptophan are also associated with higher willingness to cooperate rather than compete. One last note: tryptophan is probably LESS likely to affect your sleepiness if you've eaten a lot, since it is competing with a host of other chemicals also entering your blood-stream.