You Are Feeling Sleepy

The LA Times busts a Thanksgiving myth:

Was it the turkey? More specifically, was it the tryptophan in the turkey?

Well, yes and no. Turkey does contain a large amino acid called tryptophan. So eating turkey puts some tryptophan into your bloodstream. But there are lots of other large amino acids riding around in there too. And, of course, turkey isn’t all you gobble up at Thanksgiving. There’s a lot of other stuff on the Thanksgiving plate, and a lot of it is carbohydrates.

When you eat carbohydrates, the pancreas releases insulin, and one effect of that is to lower the levels of all the large amino acids in your blood — except for tryptophan. The upshot? You have relatively high levels of tryptophan in your blood, and in your brain that’s converted into the neurotransmitter serotonin, and that can make you sleepy.

(hat tip: Janet Stemwedel)