Postprandial Somnolence 101: What Is a Food Coma and How Can You Prevent It?

If you’ve just had a big meal and are suddenly feeling too tired to go back to work, head out for a walk, or even get out of your chair and clean up the table, you are not alone. This feeling of drowsiness after a meal – officially named postprandial somnolence but known to most as food coma – is very common.

In 2014, the term “food coma” made its way to the Oxford dictionary, which defines it as a state of sleep or lethargy that occurs after a copious meal and notes that it tends to happen the most around the holiday season. In fact, some call it the “Thanksgiving food coma” because many Americans tend to overeat on this holiday. However, food comas can happen all year round. For some, they occur daily.

What is a food coma and why does it occur? Is there any way – other than avoiding sizable meals – to prevent post-meal sleepiness? This article will answer all your food coma-related questions.

What Is a Food Coma?

A food coma is the extreme fatigue, sleepiness, and lethargy people experience after they’ve had a large meal. This feeling typically lasts for several hours and is often accompanied by bloating and stomach tightness. Some people don’t have to eat a large meal to experience a food coma. Instead, they will experience a sudden drop in energy levels every time they consume certain types of food.

There are no official statistics that would confirm how prevalent postprandial somnolence is. However, it is safe to assume that most people will experience multiple food comas in their life.

What Causes a Food Coma?

Despite its colloquial-sounding name, food coma is an actual physical condition that has piqued many scientists’ interest, especially in the last few years. Researchers have different ideas as to what causes food comas.

In line with the official definition of postprandial somnolence, many authors believe that it occurs as a direct result of eating a meal that is rich in calories and/or fat. This belief is based on two studies. One, a rat study conducted in 1991, found that high levels of the hunger-suppressing hormone cholecystokinin (CCK) not only reduce hunger but also promote sleep. The other, a small UK study conducted in 1997, found that eating meals that are high in fat and low in carbohydrates raises the levels of CCK in the body.

Expanding on the suggested link between high caloric intake and CCK, some researchers believe that food comas are the result of the fullness signals being transmitted to the brain. According to them, just like hunger keeps your brain awake, the feeling of fullness reduces its alertness and increases sleepiness.

Speaking of the brain, some researchers say that food comas occur when a portion of the blood that would normally travel to the brain is redirected to the digestive organs. You see, eating is one of the activities that trigger your parasympathetic nervous system (PNS). Among other things, this part of the brain is in charge of keeping your blood pressure and heart rate under control right after a meal.

As you fill your stomach with food during a meal, it expands. This activates the PNS, which then sends signals to the rest of your body to divert some of the blood flow to the digestive organs, thus allowing them to process the food you’ve just eaten more efficiently. Because there’s less blood – and therefore less oxygen – traveling to the brain, you may feel tired for a few hours until the meal is fully digested.

Do Certain Foods Trigger Food Comas?

Some scientists believe that the causes of food comas are more specific than just eating a big meal.

Justifying the nickname “Thanksgiving food coma”, some experts say that the high levels of the essential amino acid L-tryptophan in turkey are directly responsible for postprandial somnolence. This amino acid is a precursor of serotonin, a neurotransmitter that has a calming effect on your brain. Turkey is loaded with L-tryptophan. In the presence of carbohydrates from stuffing and mashed potatoes, your body starts converting L-tryptophan into serotonin, boosting your levels of this neurotransmitter as a result.

Both L-tryptophan and serotonin are known to stimulate the production of melatonin. In addition to its other roles, this hormone regulates your circadian rhythm. As the day draws to a close, your melatonin levels naturally rise and inform your brain that it’s time to go to sleep. With your melatonin levels up after eating turkey, your brain will enter sleep mode no matter what time of the day it really is.

Of course, turkey is not the only food that can trigger a food coma. Several other foods contain high levels of L-tryptophan, including dairy products like milk and cheese, red meat like lamb, beef, and pork, as well as nuts, seeds, and soybeans. Poultry other than turkey – particularly chicken and goose – is also rich in L-tryptophan. Spinach, salmon, and eggs round out the list of tryptophan-rich foods.

Can You Prevent a Food Coma?

You can probably already guess that most experts recommend avoiding large meals as a way to prevent food comas. Seeing as some evidence suggests that solid meals are more likely to cause postprandial somnolence, you should avoid all-solid meals, too. Ideally, your meals should be smaller and consist of both solids (e.g. a hard-boiled egg or a sandwich) and liquids (e.g. soup or freshly-squeezed orange juice).

In addition to cutting your portions, you should also limit your intake of fat-heavy foods, especially if they contain the unhealthy saturated fats. Ideally, every meal should be a combination of three key macronutrients – protein, carbohydrates, and healthy fats – in moderate quantities.

Adjusting your diet is not the only way to prevent a food coma, though.

According to a 2012 study of British drivers, the effects of postprandial somnolence are more severe in people who are tired due to either a temporary lack of sleep or chronic sleep deprivation. As such, getting enough restful sleep at night could make the symptoms of a food coma considerably milder.

Also, rather than sitting in your chair or taking a nap after a meal, you should go for a walk or engage in some other form of physical activity. That way, you will improve your circulation and help your brain fight the effects of a food coma. Plus, you will feel better about all the calories you have just eaten.

No More Post-Meal Sleepiness

While food comas are completely normal, experiencing sudden sleepiness in the middle of your workday can be very inconvenient. Of course, there are times when you can’t – or don’t want to – avoid a food coma, like when visiting your family for the holidays or organizing a pizza party with friends. Outside of those special occasions, you can keep postprandial somnolence at bay by cutting your portions, balancing macronutrients, getting enough sleep at night, and being physically active after a meal.