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Why do big meals make me so sleepy?

Yesterday, anticipating a stressful day, I ordered my usual order from Panera, whose festival of fat and carbs always makes me feel better: Broccoli and cheese soup in a bread bowl, a cinnamon crunch bagel, and a kitchen sink cookie (which has toffee, sea salt, and plenty of chocolate). When I consume this combo, I prepare myself for the wave of drowsiness that inevitably washes over me 10 minutes after I’m done. I’ve long accepted this reality but still wonder about why big meals make me so sleepy.

Weirdly enough, the soporific effect that a rack of ribs or a giant burger actually has a medical name, someone with knowledge of the matter tells me. “Some have referred to a food coma or the sleepy feeling that you get when you eat a big meal as ‘postprandial sleepiness’ or ‘postprandial somnolence,’” says Lauren Broch, a New York-based psychologist and nutritionist at Northwell Health. The term literally translates from smart-scientist-speak to after (post) meal (prandial) sleepiness (somnolence).

So truly, why does that second piece of peach cobbler after dinner make you suddenly feel like you need to go to bed? First things first: Not all food comas are created equal. There’s a mischievous and complex process happening in your body that involves several different systems.

“The expression ‘food coma’ is a more sensationalized term that refers to what happens when someone overeats; generally eating more calories, including fat and bulk than they normally do,” Broch says. The stomach will expand beyond its normal size to accommodate the large amount of food, and in turn, the distended stomach will push against other organs, she tells me. That image sounds way grosser than it feels and kind of makes me only want to eat salad, water, and hope for the rest of my life.

But wait, there’s more! “To digest the load of food, organs also have to work harder and will secrete extra hormones and enzymes to break the food down,” Broch adds. “But, these enzymes come in limited quantities so a large and unhealthy meal will take a long time to digest. This can lead to feeling sluggish, drowsy, and tired.”

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Let’s take a fun detour to explore the discomfort that sometimes accompanies the sleepiness when you down an entire order of Chicken Tikka Masala in one sitting. “The intestines have to further digest the food you’ve eaten, which can cause extra gas,” Broch says. This apparently exacerbates the uncomfortable feeling of fullness we experience. All of that extra work that is being done to digest can speed up for metabolism, which can lead to a feeling of being hot, sweaty and sometimes even dizzy. And that’s exactly why the charming term meat sweats exists. “And, if you overeat frequently, over time, this slowed digestive process means the food you eat will remain in the stomach for a longer period of time and be more likely to turn into fat,” Broch adds. Cool, cool.

“Another unwanted effect may be heartburn, since the extra acid needed to break down the food in the stomach may back up into the esophagus,” Broch says. “Heartburn occurs more prominently with fatty and fried foods that are usually incorporated in a big meal,” Broch says.

This is partially the reason why you’ll remain active if you eat quinoa and half a roasted chicken, but if you opt for an Instagram-friendly ice cream sundae, you want to go to bed at 4 PM. “Less healthy food generally contains more refined, simple carbs — sugar — and fats, which puts an immediate stress on the digestive process, increasing insulin to deal with the higher glucose and enzymes to break down fat,” Broch says.

Vegetables, while they may be sweet (like tomatoes or corn) at times, don’t have anything refined in them at all, since they came out of the ground. They also contain more complex carbohydrates which release glucose in a more sustained way, taxing the digestive process less, because the human body wasn’t made to be able to handle refined food.

And if you’re thinking of the coming holiday, yes, turkey dinner does fall under the category of food coma culprits. “One theory believes that L-tryptophan, an amino acid, is responsible for the sluggish feelings typically experiences during Thanksgiving dinner,” Broch says, because turkey contains a decent amount of tryptophan. According to this theory, digestion of the tryptophan in combination with carbohydrate-rich foods like stuffing, mashed potatoes, and all that other stuff I would list if it wouldn’t make me so hungry that I stop writing and go eat, enters the bloodstream and boosts serotonin levels. Serotonin and tryptophan, I’m told, are both precursors to the production of melatonin, which is the hormone that regulates your sleep cycle. Broch insists that the science on this is still developing, but it feels extremely spot-on to me.

So, is there any way to prevent yourself from going into a food coma if you want to eat 18 buffalo wings chased by curly fries for lunch? It really depends on your body and past experiences. “My best guess would be if you have had that experience before, it’ll probably happen again,” Broch says. “Perhaps the most conservative recommendation would be to have half of each bowl?” Ah, moderation. Such a simple ask, yet so hard to accomplish.

From deep-fried oreos to clams, thanks to Grubhub, Americans have easy access to almost any type food we want — and massive quantities of it if our wallets permit. That’s part of the problem with why human beings are getting sleepy after they eat: Many of our diets contain large amounts of processed and refined foods that our stomachs are simply not equipped to digest on a regular basis.

So, think about that the next time you take a post meal nap — is it happening too often or do you sometimes exercise some blessed restraint. “We are mainly designed to eat things that are in nature, plain and simple,” Broch says, adding that every so often, we can indulge. “Just do it sensibly,” she says.