Indykb | Dreamstime.com A typical Thanksgiving meal has 3,000 calories and 229 grams of fat.

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Thanksgiving Dinner

Most likely, it's the whole traditional Thanksgiving meal that can produce that after-dinner lethargy. The meal is quite often heavy and high in carbohydrates -- from mashed potatoes, to bread, stuffing and pie -- and your body is working hard to digest that food. After all, the average Thanksgiving meal contains 3,000 calories and 229 grams of fat [source: Meeks]. Also, if you drink alcohol with your dinner, you'll likely feel its sedative effect, too.

But there is a way to take advantage of the tryptophan in turkey. If you have trouble getting to sleep one night while there's still leftover turkey in the refrigerator, you could have a late snack of turkey and that, nutritionists say, might be the right amount of tryptophan on an empty stomach to help produce some serotonin.

­For more information about tryptophan and related articles, visit the next page.