Does your couch look more appealing after having a large meal? If it does, you are probably going through postprandial somnolence, widely known as food coma.
According to Nutrition and Psychology expert David Levitsky, drowsiness is caused by redistribution of blood flow from the brain to the intestinal vessels after a meal. "The rest and digest (parasympathetic) system are activated when you eat, but the extent to which it induces sleepiness depends on the magnitude of the meal.”
The odds of getting a food coma also depend on the type of food consumed. Dr. William Orr and his colleagues found that a solid meal creates more sleepiness compared to liquid meals. This is because liquids and solids activate different parts of the stomach and stimulate different parts of the brain. Liquids are processed in the upper section of the stomach (fundus) whereas solids are processed in the lower section (antrum). “It is more likely that the antrum has connections in the brain that are prone to induce sleepiness”, he added.
"It is theoretically possible that after eating a large (protein-rich) meal, you may feel more tired," Levitsky said. Proteins delay gastric dumping, causing the food and its surrounding blood supply to remain in the stomach for longer hours. A similar case can be made for fat, which also takes longer time to digest.
There is a longstanding belief, propagated by popular media, that turkey possesses an exceptionally high amount of tryptophan, the culprit in the post-meal doze. But this is not true given that turkey does not contain a significant amount of tryptophan compared to other meats. While tryptophan does induce drowsiness, it does not typically have that effect when consumed as part of a meal.
Rather than tryptophan, insulin is the key. This hormone is produced to help moderate blood sugar, which spikes after a meal. The larger the meal, and the more carbohydrates and proteins it contains, the higher the blood sugar spikes. As a result, more insulin is produced. This, however, is not limited to sugar. Many of these insulin receptors are in the hypothalamus, a region of the brain controlling various aspects of the nervous and endocrine systems.
Circadian rhythms contribute to food comas, too. In our bodies, there is a normal decrease in arousal that occurs in the early to mid-afternoon, a biological phenomenon that contributes to sleepiness and is compounded by eating a meal. “The natural biological clock that induces sleep happens at 2:00am to 4:00am and again between 2:00pm and 4:00pm in the case of adults. The transition occurs during teenage years, which tend to disturb the sleep patterns initially,” Orr explains.
What else induces post-meal sleep?
Energy expenditure: An appreciable amount of energy is spent in an attempt to metabolize the food. This may give a feeling of laziness and sleepiness especially when high-calorie foods are consumed, as it requires higher energy expenditure to support the process of digestion. However, when you experience extreme fatigue and symptoms like diarrhea or constipation, it’s best to consult a physician as these can be indicators of other health issues.
Psychological impact: A large sit-down meal is often the end point of a day’s work, a time to take a break, or the capstone of a holiday celebration or gathering. This deceleration contributes to a psychological effect that makes you feel more listless or tired.
Body composition: Recent evidence shows that obese individuals experience more sleepiness (tiredness) than normal weight individuals.
Alcohol: If the meal has a place for some alcohol, it could lead to headaches, dizziness, confusion, and sleepiness. This is a short-term result, however.
More than drowsiness, heart attacks has been estimated to occur four to seven times higher in people who consume heavy meal. Studies suggest that fatty dinners may lead to blood clotting more easily, which could explain the heightened risk of heart attacks, especially for people with high blood pressure.
Though a food coma may seem inevitable at times, these tips can help:
Eat small meals. The bigger the meal, the greater the chance you'll be drowsy. "We have to consciously put small amounts of food on our plates," said Levitsky. At lunchtime, small portions are especially important, because the lunchtime dip in arousal compounds the effects. “If I want to avoid postprandial sleepiness, I will have a light lunch," Orr said.
Have an early lunch. "If you eat at 1:00pm that's right at the time of the endogenous circadian dip," Orr said. It's better to eat an earlier lunch about 11:45am rather than a later lunch at, say, 1:00pm or 1:30pm, right when that dip occurs.
Choose liquids over solids. It does not mean lunch has to be limited to smoothies, though occasionally they're fine as a mini meal. "If you have a salad or a bowl of soup as opposed to a hamburger, or something with more of a liquid consistency, with higher water content, that is a better option," Orr said.
Opt for carbs that are low on the glycemic index (GI) over ones that are high. Low-GI carbs include whole wheat bread, oatmeal, beans, peas, most fruits and non-starchy vegetables. Limit white bread, white rice, bagels, pretzels, and crackers.
Grab a cup of coffee. "You can counter the effects of sleepiness after a meal by consuming caffeine," Levitsky said. A cup of coffee or cappuccino should suffice. Though caffeine can serve as a helpful stimulant, too much can lead to restlessness and can interfere with sleep later on.
Skip the wine and martinis. "Alcohol is a sedative, so this just adds to the drowsiness," Orr explained. If you enjoy a drink with a meal, choose dinnertime over lunch, and limit yourself to one beverage.
Take a brisk walk. This can help shift control away from the parasympathetic nervous system. Although it may feel burdensome to try any form of exercise while experiencing a food coma, exertion is one of the few ways that can consistently speed up recovery. If you feel cramping, though, stop and rest immediately.
A food coma, in and of itself, does not have side effects unless you fall asleep while driving or in a compromising position around friends with video cameras, markers, and some free time. However, the key thing to remember is that food comas are not supposed to be normal occurrences in a healthy diet.