(Inside Science TV) – Thanksgiving Day can be a food lover's dream. But, there is one myth about turkey day that must be put to rest.

The famous post-Thanksgiving meal nap and fatigue is often blamed on the tryptophan found in turkey. But, your drowsiness may not have that simple an explanation.

Tryptophan is an amino acid that is naturally found in most meats. When it's combined inside the body with carbohydrates, tryptophan is metabolized into serotonin, which in turn can produce melatonin. These natural chemicals promote sleep and relaxation.

But other things may be even more important in making you sleepy. According to research from the Calorie Control Council, the average American may consume more than 4,500 calories, and 229 grams of fat on Thanksgiving Day – that's more than two and a half times more calories than on a typical day! The body needs to work overtime to process all that extra fat and calories. And this takes energy — which can knock you off your feet.

And really, any big meal loaded with meat and carbs – and let's not forget the alcohol – can make you feel drowsy and want to make a bee-line for the couch.

For most of us, Thanksgiving is a once-a-year tradition of overindulgence, and the heavy dose of sleepiness will pass. But just remember, the turkey didn't do it alone – it had helpers.

Reprinted with permission from Inside Science, an editorially news product of the American Institute of Physics, a nonprofit organization dedicated to advancing, promoting and serving the physical sciences.