Calories give us energy, so why do big meals make us sleepy? This counterintuitive experience is a common one, and that goes double on Thanksgiving, where the average American packs up to 3,500 calories in a single meal. And while many people blame the turkey’s tryptophan for their soporific state, the truth is that other foods — like cheese and eggs — have just as much of the sleep inducing amino acid.

So what gives? It turns out that a few factors conspire to make the Thanksgiving meal the sleepiest yet.

First of all, if you’ve traveled for the holidays, shifts in your schedule, stress or even slight jet lag can take their toll regardless of what you’re eating. But, add to that a few hormonal shifts that happen in the body after a chow down, and you’ve got a recipe for food coma.

For one, high-carb, high-fat and high-sugar foods (like, say, buttery mashed potatoes and pumpkin pie) trigger a neural response as soon as they hit the small intestine, explains Scientific American. That response, in what’s called the parasympathetic nervous system, tells our body to slow down and focus on digesting rather than go out and seek more food.

More specifically, researchers found, a group of brain cells called orexin neurons that are found in the hypothalmus are very sensitive to glucose levels, which spike after a big meal. Those neurons produce a protein, orexin, which moderates wakefulness in the brain.

But orexin isn’t the only sleep-related neurohormone affected by food. As the quantity of food increases, so too does the amount of insulin released as a normal part of the body’s digestion. The insulin, in turn, increases the amount of seratonin and melatonin that flood the brain, two chemicals associated with drowsiness (and, for that matter, happiness).

While there’s no way to avoid a sleep response to a big meal (other than reducing the overall amount you eat and lowering fat, refined carbohydrate and sugar in the first place), it isn’t dangerous or a sign of a greater health problem.

It’s important to note that having a big meal can affect the important rest you need later in the evening. That’s particularly true for those who eat late — as often happens during a celebratory meal like Thanksgiving.

As Dr. Loren Greene, a clinical associate professor in the Endocrinology Division of the Department of Medicine at NYU previously explained to HuffPost Healthy Living, “If you eat a late dinner, say 10 p.m. with a dessert, some times you start putting out insulin in the middle of the night which can cause your blood sugar to peak and drop,” Greene says. That, in turn, can disrupt the sleep cycle, waking you in the middle of the night or preventing one of the deeper sleep cycles we require for true restfulness.

The moral of the story? Eat early, eat smart and try to get yourself back on your normal eating and sleeping schedule as soon as possible.

Here’s more on myths about the Thanksgiving meal:

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  • Turkey Makes You Tired

    We’ve all heard that the trigger for those post-feast naps we can’t seem to resist is the tryptophan found in turkey. The theory goes that tryptophan, an amino acid, is converted in the body to serotonin and then converted into <a href=”http://www.nlm.nih.gov/medlineplus/druginfo/natural/940.html”>melatonin</a>, which affects the body’s sleep cycles. But the truth is, according to <a href=”http://www.everwell.com/”>Davis</a>, other foods, such as cheese, eggs and other kinds of meat, contain just as much if not more of the amino acid.

    The most likely culprit for the sleepiness is the amount of carbs (and alcohol) we consume at Thanksgiving dinner, he says.

  • A Multigrain Roll Is A Healthy Roll

    Just because it’s a brown roll doesn’t mean it’s healthy. Chalk this one up to a marketing tool: Davis explains that “multigrain” just means that there are multiple grains, which could potentially include a variety of refined grains and none of the heart-healthy whole grains. “Multigrain rolls might not be any better than white enriched rolls,” Davis says.

    How to find a truly whole grain roll? Do a little detective work in the store: Davis says the first word on the ingredient list should be “whole.” Look for labeling that says whole grain or whole wheat — but not “made with whole grain,” which could still leave room for refined grains.

  • You Should Always Choose Sweet Potatoes Over White Potatoes

    In a straight-up nutritional face-off, sweet potatoes would win: with about the same number of calories, they have more fiber and vitamins A and C than their white counterparts. But preparation matters: two scoops of sugary, candied sweet potatoes are not the nutritional equal of a plain, baked white potato. (And white potatoes, the ones that aren’t slathered in butter, have their own health benefits — <a href=”http://www.huffingtonpost.com/2012/06/29/healthy-food-healthiest-list_n_1636409.html#slide=1161988″>check them out here</a>).

  • Dark Meat Is Unhealthy

    While it’s technically true that white turkey meat without the skin is the healthier option — with about 158 calories and 0.5 g of saturated fat per four-ounce serving, according to Davis — dark meat isn’t necessarily <em>unhealthy</em>, especially compared to other types of meat, such as red meat. At 183 calories and 1.6 g of saturated fat per serving (without skin), you can satisfy your craving without blowing it nutritionally. And dark meat contains more of certain nutrients than white, including <a href=”http://www.nytimes.com/2007/11/20/health/nutrition/20real.html?_r=0″>zinc and iron</a>.

    “The point is if you like dark meat better, you’re not necessarily getting a lot more fat and calories,” Davis says. “The bigger concern is keeping portions in check rather than, ‘Am I eating too much dark meat?'”

  • Thanksgiving Cranberry Sauce Can Reduce UTIs

    Studies have shown that cranberries may really be effective at <a href=”http://www.huffingtonpost.com/2012/07/12/cranberries-uti-cranberry-urinary-tract-infection_n_1662946.html”>preventing urinary tract infections</a> for some people, Davis says. But he points out that’s when you eat them regularly, not once a year with your turkey dinner. “Obviously just eating with your Thanksgiving meal is not going to do the trick,” he says.

    What’s more, while whole cranberries are healthy, when they’re jellied into sauce, they can be loaded with extra sugar and calories.

  • Pigging Out One Time Isn’t A Big Deal

    We’ve been called killjoys a time or two (or 100) from people who say one unhealthy meal can’t do any real damage. But the truth is that it can: research has linked a single high-fat meal to <a href=”http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170142/”>impaired vascular function</a>.

    If you do overdo it at the dinner table, focus on getting <a href=”http://www.huffingtonpost.com/2011/11/25/thanksgiving-detox_n_1108632.html”>back on track the next day</a> — but we’d suggest avoiding the all-out binge in the first place (there will always be leftovers).

  • Pop-Up Timers Are A Good Judge Of When The Turkey Is Done

    Pop-up timers might be convenient — but they’re not always reliable, Davis cautions, which can become a food safety problem. “People should also use a conventional food thermometer, placing it in the innermost part of the wing and thigh and thickest part of the breast to ensure that the turkey is cooked to at least 165 degrees F all over,” he says. For more, <a href=”http://www.foodsafety.gov/blog/thanksgiving_turkey.html”>click over to FoodSafety.gov</a>.

  • Red Wine Is The Only Healthy Alcohol To Toast With

    While red wine has a (well-deserved) <a href=”http://www.mayoclinic.com/health/red-wine/HB00089″>health halo</a>, the truth is that other forms of alcohol, including white wine and liquor, are also associated with a lower risk of heart disease, Davis says: “Scientists haven’t shown that drinking red wine is better than other forms of alcohol in these long term cohort studies.”

    But remember you can only reap those benefits in moderation — that means no more than one drink a day for women and no more than two for men. Beyond that, the <a href=”http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Alcohol-and-Heart-Disease_UCM_305173_Article.jsp”>risks outweigh any benefits</a>.

  • Canned Pumpkin Isn’t As Healthy As Fresh

    We often hear fresh veggies are preferable to canned, but that’s not necessarily true when it comes to pumpkin. Because canned pumpkin is more concentrated than fresh, it has two to three times more fiber and vitamin A, according to Davis (one note of caution: being more concentrated also means it contains more calories). “The canned is just as good to use if not better,” he says.

    Just be sure you’re getting pure pumpkin in the can, not a pumpkin pie mix, which could have sugar, salt and other unhealthy additives mixed in.