Why Am I Sleepy After I Eat?

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Feeling sleepy after you eat is called postprandial somnolence, which is a condition that can occur after eating a large meal. It is usually described as a feeling of extreme fatigue or lethargy that can last for several hours. There are several different theories about the causes of food coma and what you can do to prevent the condition from occurring.

What Is Postprandial Somnolence?

If, after a big meal, you hit the couch, get comfy, grab the remote, and spend the rest of the afternoon or evening lounging in a semi-vegetative state, you've most likely experienced the effects of postprandial somnolence.

You've heard that this is called a "food coma," but is a food coma a real thing? Yes, as it turns out. Food coma, also known as postprandial somnolence or sleepiness, is an actual condition that scientists have studied.

While the cause of after-meal sluggishness is up for debate, there is no confusion about the symptoms: laziness and heaviness, usually accompanied by bloating and a feeling of tightness in the belly.

Causes

There are different theories about the causes of postprandial somnolence. Researchers have studied the condition for years but don't necessarily agree on why the condition occurs.

Eating Foods With Tryptophan

Have you ever experienced a food coma after Thanksgiving dinner? Many health experts attribute this post-meal slump to the high levels of L-tryptophan (commonly called "tryptophan") in turkey. Tryptophan is an amino acid found in particular meat and dairy products.

When this amino acid is consumed along with carbohydrate-rich foods (like mashed potatoes and stuffing), it easily enters the brain and boosts serotonin levels. Serotonin is a neurotransmitter that decreases arousal, so you're likely to feel more relaxed and even lazy when elevated serotonin levels.

Tryptophan and serotonin also play a vital role in the production of melatonin in the body. Melatonin is a hormone that helps the body prepare for sleep.

Changes in Blood Flow to the Brain

Some health experts say that postprandial somnolence is caused by a slight shift in blood flow away from the brain to the digestive organs. Eating activates your parasympathetic nervous system (PNS).

The PNS regulates body functions like heart rate, blood pressure, and digestion. The PNS is triggered when the stomach expands from eating a big meal. As a result of PNS signals, blood flow is directed more to the working digestive organs and less to the brain. This slight blood flow diversion may cause you to feel sleepy and tired.

High-Fat or High-Calorie Meals

Some researchers have questioned both the tryptophan theory and the link between blood flow changes and food coma. Instead, they propose that eating a meal that is high in fat and low in carbohydrates can cause post-meal sleepiness.

Researchers have proposed that a complex combination of satiety signals is sent to important sleep centers in your brain after eating a solid meal that is high in fat and/or high in calories. The signals decrease arousal and hunger signals in the brain and increase sleepiness.

Increase in Cytokines

Interleukin-1 (IL-1) family cytokines are signaling molecules involved in the inflammatory response and other processes. Researchers believe that these particular cytokines are responsible for increased post-meal fatigue.

The reason being, that when people take the medications used for reducing inflammatory responses, this postprandial somnolence effect is less common and less intense. Cytokines can increase the perception of fatigue by affecting the central nervous system.

Prevention

If you want to avoid landing on the couch for hours after your next indulgent meal, you can follow a few guidelines.

Eat Smaller Meals That Include Liquids

Large meals are more likely to induce post-meal fatigue. In addition, most experts agree that solid foods may cause that familiar feeling of after-meal sleepiness. If you want to stay alert after lunch or dinner, it might help to consume a smaller meal and make part of it liquid (such as soup or a smoothie).

Get Enough Sleep 

If you plan to drive after a big meal, ensure you are well-rested before eating. One study of drivers who got behind the wheel after eating a big lunch found that a larger meal worsened inherent sleepiness. That means if the driver was already sleepy, eating the big meal made it much more exaggerated.

As well, lack of sleep may increase the likelihood that you'll reach for high-calorie and fat foods, which can also increase post-meal fatigue. These foods may not keep you feeling energized either, making a sluggish feeling even more likely.

Balanced Meals

Even though they disagree on the mechanism in action, researchers seem to agree that fatty meals are more likely to make you sleepy in the hours after eating. If you build balanced meals around a moderate intake of protein and carbohydrates with a small amount of healthy fat, you may be less likely to fall victim to ​a food coma.

As well, choosing a variety of foods as part of balanced meals, including fruits, vegetables, whole grains, healthy fats, and protein sources will ensure you get the vitamins and minerals that can boost your energy and prevent fatigue. These include iron, B vitamins, magnesium, potassium, carnitine, and more.

Control Your Portions

Keeping portion sizes in control should help keep food coma at bay. A single portion of meat or fish is just three to four ounces. A single portion of starchy carbohydrates is one cup, or about the size of your fist. A single serving of fat is usually one to two tablespoons.

As well, the bigger the meal, the more insulin will be released, which scientists believe can cause a drowsy feeling. Insulin impacts certain neurotransmitters involved in the sleep/wake cycle, nervous system, and endocrine syndrome. This includes dampening the production of one neurotransmitter called orexin that helps keep you feeling alert.

Get Active After Your Meal

Increase circulation and stimulate your muscles after a big meal with a short walk or activity session. Activity can invigorate your body to keep fatigue symptoms at bay. Getting active in general can increase your energy levels and help with digestion.

As well, activity like walking after meals improves blood sugar levels, which may also help reduce fatigue. If you've eaten a high-fat meal, however, your digestion will be slowed and this may cause nausea and even vomiting, so stick to light exercise like a walk or gentle cycle.

A Word From Verywell

While feeling very tired after a meal isn't comfortable, an occasional episode of postprandial somnolence isn't likely to cause harm. In fact, it may remind you to stick to smaller, less fatty meals next time. So rest after your big meal if you need to. Then use reasonable food practices most of the time to keep your body healthy, active, and alert.

10 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Malia Frey
 Malia Frey is a weight loss expert, certified health coach, weight management specialist, personal trainer​, and fitness nutrition specialist.