This is tryptophan. OK, it’s not a vitamin, it’s an essential amino acid that we get from food. You may have heard that it makes you sleepy, and it actually can help you sleep, but probably not in the way that you’ve heard.
No Thanksgiving dinner is complete without some uncle or cousin informing the gathering that the Turkey they are eating is loaded with tryptophan, and that it functions as a sort of knock-out drug to make us all collapse on soft furniture after dinner. Not quite.
First off, tryptophan levels in turkey are the same as in chicken and most other meat. Egg whites have about four times as much tryptophan, and we eat them for breakfast!
However, Postprandial Somnolence (which, apart from being an excellent name for a long lost Emerson Lake and Palmer album, is a sciencey way to say afterdinner sleepies) is a real thing, and tryptophan does play a part. But do you know what else plays a part? Pie. And mashed potatoes, and rolls, and all of the other carbohydrates you eat with the turkey. The carbs trigger the release of insulin, which stimulates the uptake of other amino acids into the muscles, leaving an increased level of tryptophan in your blood that can then be absorbed into the brain. The tryptophan is converted to serotonin, the serotonin is metabolized into melatonin, and, it’s the melatonin that makes us sleepy.
I got sleepy just writing that last paragraph. You too? Go ahead, take a little nap.
When you wake up, there will be leftovers in the kitchen, and maybe one more slice of pie?