In addition to being full or too full, feeling sleepy is actually related to what you ate?

Do you have the habit of taking a nap? As the saying goes, "If you don't take a nap at noon, you will feel sleepy in the afternoon." After having a good lunch, it is the habit of many people to lie down and take a nap comfortably. But why do you feel sleepy after eating?

In fact, this phenomenon is not limited to humans. Mice, snakes, some insects, and even lower organisms such as Caenorhabditis elegans will feel a little sleepy or less active after a full meal. This phenomenon is very common, but the reasons behind it can be very complicated.

A 1983 study found that a variety of factors, including hunger levels, food intake, and food composition, all affect how sleepy you feel after a meal.

Some subsequent studies further confirmed this conclusion.

In a paper published in 2012, researchers found that people who ate a full meal were more likely to veer off course during a simulated driving experiment than those who ate only half full, which meant they were more likely to have an accident. EEG monitoring showed that these people also felt more sleepy while driving.

In addition to how much you eat, scientists have also found that what you eat can also affect your sleepiness. According to a paper published in 2018, people will feel sleepy after eating a high-calorie, high-carb meal, regardless of whether they are fat or thin. According to a study published in 2002, when eating only one meal a day, the level of melatonin in the body after eating high-carb food in the morning will be higher than the level of melatonin after eating the same type of food in dinner. This means that the time of eating may affect a person's circadian rhythm. But this is only at the speculation stage, and there is currently no clear experimental evidence that high-carb foods will make people sleepy after meals.

The picture comes from Tuchong.com

Since the problem of sleepiness after meals involves too many factors - digestion, nerves, endocrine... various factors are mixed together, so we still can't figure out what makes us "not sleep at noon and collapse in the afternoon". But this does not prevent us from solving this problem.

For example, a 2015 study found that exposure to blue light after lunch can significantly reduce the level of alpha waves in the brain and improve cognitive ability. Alpha waves are a sign of brain sleepiness, and reduced activity means that people will be more awake. This means that for urban white-collar workers who sit in front of computers every day, after lunch, they may become more awake by staring at the computer screen or swiping their phones intensively, despite being sleepy.

In addition, eating a light lunch, such as vegetables, whole wheat bread, etc., or having a cup of coffee, etc., can make you less sleepy. Of course, if you really can't help it, then take a nap, after all, the old saying of our ancestors is right.

This article is a work supported by Science Popularization China Starry Sky Project

Author: The Nutcracker

Review: Tao Ning

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.