NORFOLK, Va. — On the fourth Thursday in November, loved ones meet and eat. On your table are the mains, sides, desserts and of course something to wash it all down.

By the end of the meal, you might be ready for a nap or at least a break from those plates.

Here's why:

Even if you don't eat the turkey, you can still get hit with that post-meal slump. So turkey isn't necessarily the culprit.

What's to blame is an amino acid called tryptophan. Chicken and other protein-rich items also have tryptophan but turkey gets that bad rap for making you want to nap.

We may have to shift our sleepy eyes from the poultry to the carb-heavy side dishes. 

The body is set up to release insulin to react to the increase in glucose while digesting food. Insulin absorbs the other amino acids, which upgrades tryptophan to a first-class ticket to the brain.

 There, it helps make the neurotransmitter serotonin, which precedes the sleepy hormone: melatonin.

And that's what knocks you out before halftime.

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