As the turkey was put away, the cranberry sauce packed into tupperware, and the dishes cleaned up Thursday, Americans across the country shared a collective yawn.
Before I get into this post- you may or may not have heard of tryptophan and may or may not believe it to be the source of our Thanksgiving Day sleepiness. To this, I point out that the amount of tryptophan in turkey is high, but not significantly higher than other meats, and shouldn't induce sleepiness much more than eating a rack of ribs.
The sleepiness we find on Thanksgiving may have a number of causes, and turkey may be a part of it, but definitely doesn't work alone.
Normally, our brain absorbs tryptophan and glucose into the brain. The glucose is used for energy and the tryptophan is used to make hormones, nutrients, and chemical messengers.
On Thanksgiving day you just ate a ton of carbohydrates: rolls, stuffing, mashed potatoes, sweet potatoes, casseroles, gravy, cranberries, and pie. When we eat carbs our blood is full of extra glucose molecules.
To keep our blood at normal levels, our body makes insulin, which tells the muscles to clean up and absorb the extra sugars. The muscles do this, leaving the blood with lowered glucose levels, but still the same tryptophan levels. When our brain absorbs the tryptophan and glucose, it absorbs extra tryptophan because of the lowered amount of glucose present to absorb. The tryptophan goes down a chemical pathway, which ends with sleep-promoting melatonin in the brain.
I think its time for a nap now.