I remember when I went to school, the teachers said:
I am most afraid that my class will be arranged in the first quarter of the afternoon, and I will feel that everyone will fall asleep.
Many people will also feel as if they are not only in class, but also feel sleepy and weak after noon every time, but the situation will improve in the afternoon.
This phenomenon can be called [drowsiness after meals] or [drowsiness after eating], which is a normal physiological phenomenon. Then why is this? What should I do?
Blood flows to the stomach and intestines, so the brain lacks oxygen?
There is a very popular urban legend:
After eating, food accumulates in the stomach. In order to digest the food, the body supplies more blood to the gastrointestinal tract to help digest and absorb the food. This redistribution of blood reduces the blood supply to the brain, which feels sleepy due to insufficient oxygen supply.
Is this statement correct?
It is said that it is a legend, so of course it is wrong.
The study found that the blood supply to carotid artery did not change after eating.
Cerebrovascular vessels have their own regulation mechanism. When blood pressure decreases, cerebrovascular vessels relax to increase blood supply and maintain stable blood supply. When blood pressure rises, cerebral vessels contract to reduce blood supply and still keep blood supply stable.
Is it because of after-dinner [alkalosis]?
Another explanation is that this is a physiological phenomenon called [postprandial alkali tide]:
After eating, due to gastric acid secretion and a large amount of hydrogen ions released, a corresponding amount of HCO3-ions will enter the blood, alkalizing the blood, and this [alkalization] will cause slight alkalosis, thus making people sleepy.
This explanation is also wrong.
In fact, the human body is a very intelligent regulation system. The blood pH value can be maintained within a stable range, which will not easily make the body in an unbalanced alkaline state. If there is a slight alkalization, the increase of carbon dioxide at this level may also indirectly cause cortical excitation, which is different from the drowsiness problem we are going to discuss.
It may be related to several hormones.
Another theoretical explanation, which has been proved by many experiments, is that the self-regulating response of intestinal nerves and hormones may directly act on the nerve areas that control sleep. Simply put, the body will secrete some hormones after eating, which directly act on the brain and make people tired and sleepy.
Not all hormones have been studied clearly at present, and only some of them have been briefly introduced here.
1. Cholecystokinin (CCK)
Human studies have shown that CCK levels increase significantly within two hours after meals and then gradually decrease. During this period, drowsiness is positively correlated with CCK levels. If CCK is injected into humans or animals, it will produce sedative and satisfying effects.
High-fat foods can promote the secretion of CCK and make people sleepy.
2. Orexin (Orexin, Hyporectin)
A number of human and animal experiments have proved that the low level of orexin will cause drowsiness in the human body. On the contrary, the human body will be excited when the level of orexin rises.
Orexin participates in the regulation of sleep, eating and autonomic nervous function at the same time, and plays an important role in the regulation of [blood sugar homeostasis] and the balance of energy metabolism, which explains why there is another explanation: postprandial blood sugar fluctuation can make people sleepy.
If you have had the experience that you are prone to drowsiness after eating more foods with high carbohydrate and high sugar reaction, such as white rice, various staple foods such as flour cakes, cake desserts, biscuits and potato chips, and sugary drinks, then you may be the part of the people whose blood sugar control is relatively unstable, so you should eat less staple foods and sweets.
3. Melatonin)
Melatonin is a hormone that regulates the biological clock and has been used to help sleep or treat sleep disorders. The human body can secrete melatonin, and all kinds of fresh foods contain a certain amount of melatonin, which will be lost after long-term storage or processing. When melatonin is absorbed, the human body’s response is [ah, night is coming, I’m going to sleep].
Of course, there are also some other reasons for drowsiness after meals, such as the biological clock developed during a long lunch break, or you were really sleepy and tired at that time…
What should I do if I feel sleepy after dinner?
Since postprandial drowsiness is a kind of drowsiness and fatigue, the simplest way to relieve it is to increase excitement. You can try this:
1. Less! Eat! Point!
We often say that [when you are full, you are sleepy] is reasonable. Too much food will increase drowsiness. Too much food will inevitably have more fat or sugar.
2. Eat less single high-sugar and high-fat food.
A meal that many people are accustomed to may be like this: a plate of fried rice with few ingredients, or a bowl of Lamian Noodles with few ingredients, or several large steamed buns and meat buns, or a bread or pizza…
Many fast food restaurants often have the problem of too many staple foods and too few side dishes for a set meal.
A more reasonable meal is: try to have enough vegetables, a certain amount of protein (fish, poultry, meat and eggs), plus a proper amount of staple food, and give priority to coarse cereals and potatoes.
3. Don’t stay in confined space after meals
Poor air circulation and increased carbon dioxide concentration in closed small rooms may also make people sleepy. Go out for a walk and breathe fresh air, which makes people feel refreshed.
4. Proper exercise after meals
Don’t sit down or lie down immediately after the meal, do some moderate activities, can make the whole body excited. Go out for a two-step walk. Or after a while, do some low-intensity exercises, such as squats against the wall, push-ups against the wall, squats, are all good.
If the time is convenient, you can do some intensive exercise 1 ~ 2 hours after meals.
5. Intensify the campaign
Developing good exercise habits is helpful to improve the overall sleep quality and relieve fatigue by adjusting the health level of the body.
6. You can usually drink coffee or functional drinks.
Most of them can effectively improve brain excitement, especially the caffeine in them can stimulate the nervous system, reduce fatigue and drowsiness. It is usually recommended to drink before noon, which is not easy to affect sleep at night.
Of course, drowsiness after meals is a normal physiological phenomenon. Conditions allow you to take a short rest for 15-20 minutes. There is no need to stay awake. You should rest when you have a rest.