What is tryptophan?

You have heard correctly, actually. There is a substance in turkey called tryptophan that is what's called an "essential amino acid" for the human diet. While it commonly appears in turkey, it turns out that it's also common in other foods, including cheese, chicken, beef, salmon, eggs, wheat flour and even white rice. In fact, according to Wikipedia, dairy milk has the highest ratio of tryptophan to protein of any food source, followed by eggs.

Apparently, tryptophan increases the brain levels of seratonin and melatonin and you can actually buy tryptophan in health food stores as a sleep aid. Hmm. Certainly suggests that eating a lot of turkey would make you get sleepy!

However, the sad news is that the amount of tryptophan in the turkey you eat is probably less a cause for your post-meal drowsiness than the simple fact that you've just eaten a big meal and it was probably loaded with carbohydrate-rich food. So don't blame the gobbler: if you had a tofurkey and all the same side dishes, I bet you'd be just as sleepy during the Big Game anyway.

Don't trust Wikipedia? There are plenty of other references to turkey dinners and lethargy, including a good overview at about.com, a scholarly report from MIT, and a National Institutes of Health overview. Heck, there's even an article about this at whitehouse.gov. And you though that the Command-in-Chief was busy with more important things on Thankgiving? :-)