Tryptophan, turkey, and Thanksgiving have become synonymous with one another but does anyone really know exactly what tryptophan actually is and if if actually makes you as sleepy as it's fabled to do? The truth is shocking: the levels of tryptophan in turkey is no different than any other poultry - and some other common foods have a much higher level of the amino acid than turkey does.
Eggs have the highest level of tryptophan of any food with 1.00 g/100 grams of food. Some science looking guy in a white lab coat that works here said so. Cod, soybeans, pumpkin seeds, Parmesan cheese,  and pork chops all have more tryptophan than turkey too. Even caribou has more.

In short - you're sleepy from waking up at 5A to put a turkey in the oven, dealing with relatives all day, and eating a meal loaded with carbohydrates. Oh and drinking three bottles of white wine could have made you sleep too.

asleep on couch after Thanksgiving
hoshanah, flickr