What Is A Food Coma?
Holidays, your birthday, or any joyous time you spent celebrating life’s cherished moments, you probably spent with friends at a table filled to the brim with food. Better yet, other times you don’t even have to wait for a special occasion, you indulged right at dinner.
Whether you ate a little too much on Thanksgiving or last night, an inevitable drowsiness set in and your post meal festivities got postponed.
It’s happened often enough that the phenomenon has its own special name in pop-culture. Science calls it “postprandial somnolence,” but the rest of us call it itis, dinner dip, or by far the most descriptive, the food coma.
It may come on rapidly and leave you drowsy, but there’s no need to be alarmed. The food coma isn’t inherently unhealthy, it’s simply the body’s reaction to your latest indulgence.
But even though we know the effects, we still don’t know why they come about. Drowsiness may follow a heavy Thanksgiving meal, but it isn’t exclusive to turkey day. So if the food coma isn’t particular to a specific meal, what’s the catalyst?
Debunking The Myths
Too Much Alcohol!?
A popular explanation worth considering is alcohol. It’s often paired with a big meal and plentiful during holidays and special events. Plus, depending on how much and what you drink, alcohol may act as a sedative in its own right.
That explanation makes sense when considering that a glass of wine or a couple beers mellow people out, but that explanation fails for a simple reason; large meals without alcohol still put you to sleep. So even if alcohol plays a part, it’s not significant.
Blood Shift Theory
The blood flow shift theory posits that changes in your body’s blood circulation are the catalyst for drowsiness. Here’s the idea, as you’re scarfing down your dinner, you activate your GI tract, in turn, blood flow shifts from your brain and muscle into the intestines and stomach to accommodate the process. Consequently, less blood in the brain triggers drowsiness and sleepiness.
The theory is plausible, but not probable. Your body does divert resources on an as needed basis. But a joint study1 by Stanford University and the San Mateo Medical Center has cast serious doubts.
The researchers were particularly puzzled by the theory’s persistence when considering the well documented “neurophysiological principle that cerebral perfusion is preferentially maintained under a wide range of physiologic states.”
For instance, when perfusion occurs to the muscles during exercise, blood flow to the brain is maintained.” Further, “recent evidence suggests that there is no measurable change of blood flow in the common carotid artery during postprandial states.”
Here’s a translation; exercise is a strenuous activity that requires blood diversion to the muscles. In this sense, it’s akin to digestion, which – according to the blood flow shift theory – also requires blood diversion. Hence, the theory suggests a similar process for both activities.
However, findings indicate no measurable change of oxygenated blood flow in the main artery supplying the head and neck during either activity.
Big Meal, Big Nap
One thing’s for certain, you don’t head for bed after a small meal. This notion legitimizes the idea that it’s the meal size that leads to a food coma, not what’s in the meal per se.
The idea does have some merit to it. When digesting a meal, the parasympathetic nervous system – known as the “rest and digest system,” conserves energy by slowing heart rate, increasing intestinal activity, and relaxing the sphincter muscles in the gastrointestinal tract – is activated.
When digesting a meal, the parasympathetic nervous system – known as the “rest and digest system,” conserves energy by slowing heart rate, increasing intestinal activity, and relaxing the sphincter muscles in the gastrointestinal tract – is activated. The extent to which the system is activated, and induces sleepiness, depends on the size of your meal.
It happens because larger amounts of food cause larger stomach stretches. Hence, a large meal causes more stretching, which leads to greater use of the parasympathetic system. This chain of events is a contributing factor to the post meal slumber.
Interestingly enough, liquids seem to induce sleep less than solids. This is partly because solids and liquids are digested by different parts of the stomach.
Accordingly, they provide the brain with different feedback stimuli. Specifically, liquids are digested in the upper part of the stomach, while solids are digested in the lower.
Consequently, one explanation is that the lower part, where digestion of solids occurs, provides feedback stimuli that are more likely to induce sleepiness.
The Hormone Effect
Another popular myth concentrates on tryptophan. The amino acid derived hormone was widely believed to induce post meal naps because of its presence in turkey. Considering turkey’s centerpiece role during Thanksgiving, popular thinking correlated tryptophan with post turkey feasting naps.
The pseudo science posited the brain’s conversion of tryptophan into serotonin – a neurotransmitter responsible for feelings of relaxation and sleep – as the catalyst for drowsiness. This would make perfect sense, except other foods, namely; eggs, cheese, and even pineapple, also contain the hormone.
But they don’t have the same effect as the Thanksgiving bird. More importantly, post meal tryptophan levels are not great enough to raise brain serotonin levels. Hence, the theory’s premise is right, but the qualification is not.
Another hormone thought to effectuate a food coma is CCK. The intestinal hormone is known to rise in the blood after a heavy meal. But unlike tryptophan, research concentrating on CCK found that administration of high doses to lab subjects did not result in post meal drowsiness.
The Real Deal
Though there’s ample research dedicated to debunking the myths, there’s also plenty dedicated to finding the probable catalyst.
A recent Scripps Research Institute study2 determined that “the cause of the food coma turns out to be protein and salt, along with the time of day” we have our meal.” Offering a possible explanation, the researchers noted that it could be because of the relative “rarity and value of protein, and the body expending greater energy metabolizing those nutrients.”
To ascertain that protein and salt were unique as food coma contributors, researchers added sugar to the experimental mix. To their surprise, they found that “only protein and salt were effectors of post-meal sleep, suggesting that this form of sleep can indeed be regulated by specific food types.”
Further, the study elaborated that protein’s properties are conducive to “delayed gastric dumping; a mechanism by which food and its surrounding supply of blood is kept in the stomach for a longer time period.” Theoretically, this prolonged digestion may be instrumental to food comas.
The surprising results have been mirrored by researchers from Bowling Green State University. In that study3, led by Dr. Robert Huber, the team looked into neurobiological connections between eating and sleep, concentrating on food comas in particular. Their results confirmed the Scripps study, specifically; the more protein subjects consumed, the longer they slept.
In fact, protein and salt not only affected sleep duration but also acted as catalysts. Commenting on the study, Dr. Huber opined that “if sleep increases your ability to resorb protein, then that would be a possible reason” for the body switching off the proverbial light switch after a heavy meal.
On the contrary, carbohydrates don’t prompt such an involved digestive process. Explanation? They’re plentiful and easier to come by.
The Food Coma Cure
Want to ensure you’re not hit with post big meal slumber? Here are some tips;
- If you’re eating carbs, aim for the complex variety. So stick to whole grains and vegetables. These foods are disaccharides, meaning they’re composed of two “simple” molecules and don’t cause a rapid insulin spike and crash. As a result, you have sustained energy after a big meal
- Control your portion size. It’s easy to get carried away! The chance of drowsiness increases along with the portion.
- Have some coffee. Caffeine is beloved for its early morning jolt, and there’s no reason not to enjoy a cup after a big meal. A cappuccino after dinner will work just as well after dinner.
- As an alternative, various cultures have digestive post-dinner aids. For example, Italians serve digestif to aid the body with the post meal process.