“After a hearty dinner, according to the law of Archimedes, it is supposed to sleep …”, and also “Well, you ate — you can sleep …” — most of our compatriots know these popular phrases for sure. And after all who would argue! After dinner, he often gets sleepy … For some reason, this is especially acute in the workplace after returning from the dining room. MedAboutMe found out what causes afternoon sleepiness and how to deal with it?
1. Digestive processes that cause drowsiness
In the process of digestion, food is broken down into separate molecules — fats, proteins and carbohydrates, which are used by the body for different purposes. During the process of saturation, the body produces various hormones that activate and enhance the feeling of satiety. And the hormone insulin is needed so that glucose from the blood gets inside the cells and can be used as an energy source.
For proper and efficient digestion, in particular, such an important hormone and neurotransmitter as serotonin is required for us. But the same hormone is involved in the activation of slow-wave sleep. Drosophila fruit flies generally fall asleep when serotonin increases. Of course, we are far from flies, but also, thanks to serotonin, we begin to suffer from drowsiness when its concentration in the blood increases.
There is also an opinion that another hormone, melatonin, which is responsible for nighttime sleep and generally regulates circadian rhythms, is to blame for afternoon sleepiness. It is just produced by our body from serotonin. It would seem logical: more serotonin — more melatonin — that’s drowsiness. But with melatonin, not everything is so straightforward. By itself, melatonin does not activate the sleep process, but it prepares the body for it and prolongs the state of sleep. And the production of melatonin does not depend on the amount of serotonin, but on the length of daylight hours.
Another important point: if too much is eaten, the body redistributes resources towards the digestion of food, taking them from organs that, in its opinion, currently need it less — from muscles, for example. At the same time, blood flow increases to the following organs: stomach, intestines, liver and pancreas. As a result, a person feels tired, relaxed and completely unwilling to move anywhere and do anything. He wants to lie down and sleep.
Fluid intake with meals also plays a role. Too little fluid leads to a state of dehydration, low blood pressure and increased drowsiness. Too much liquid negatively affects the digestion process.
How to eat so as not to fall asleep after eating? First of all, don’t overeat! It is better to have a couple of very light snacks than one full three-course meal, dessert and a glass of sweet tea.
2. “Sleepy” foods
And serotonin is produced from the essential (that is, we don’t know how to make it ourselves) amino acid tryptophan, which must get into the brain tissue for this. There is a lot of it, for example, in turkey meat or in egg white. But the love of a turkey or egg white does not guarantee pathological drowsiness — there are a number of biochemical nuances that do not allow a direct relationship between a piece of turkey and the desire to sleep.
The list of foods rich in tryptophan also includes: spinach, soy, cheese, tofu, cod, pork, and even bananas — that’s definitely not something you should snack on, especially if you have to travel as a driver.
However, a minimal “drowsy” effect is possible. And it increases if tryptophan enters the body in combination with glucose: this activates the process of insulin secretion, and the tissues begin to absorb more amino acids — more tryptophan is in the brain tissues.
To reduce the risk of daytime sleepiness, you should not eat the above foods in the middle of the working day.
3. Lack of sleep
All of the above “food” effects that cause drowsiness are greatly enhanced if a person is in a state of sleep deprivation, and especially — a chronic lack of sleep. When a person does not get enough sleep on a regular basis, his body catches any moment of relaxation in order to put its owner into rest mode and get the missing sleep.
It is impossible not to add: daytime sleep itself is not so bad! Moreover, NASA experts claim that a 10–20-minute nap during the day increases a person’s alertness and performance, increases reaction time, attention and memory.
And a 2021 study published in the British Medical Journal found that in older adults 65+, short naps reduce the risk of dementia.
A healthy activity and rest regimen, 7–8 hours of sleep a night will reduce the risk of developing daytime sleepiness — or at least give strength to fight it.
4. Lack of physical activity
Regular physical activity helps to keep yourself in a cheerful state of mind even after a hearty meal. Training energizes you for the whole day, preventing you from falling into sleep and feeling tired. Just relaxing at home on the couch does not give such an effect. In the absence of regular physical activity and a sedentary lifestyle, there is nothing to oppose the feeling of daytime sleepiness.
But at the same time, excessive loads can have the opposite effect and cause all the same drowsiness. If in the middle of the working day you go to the gym with “iron” and work there to the limit, then the body will rightly judge that recovery is much more important than office activities. And after a tight snack, drowsiness will flood over with the “ninth wave”.
So if you’re doing a sport in the middle of the day, it should be energizing, not draining you dry.
5. Diseases that cause drowsiness
Drowsiness after eating and in general for any reason can be one of the symptoms of a number of diseases:
- diabetes. Other symptoms: dizziness, weakness, constant feeling of hunger, irritability, periodic “fog in the head”;
- hypothyroidism. Other symptoms: chronic pathological fatigue, weight gain, chilliness, brittle hair and nails;
- sleep apnea. Other symptoms: chronic lack of sleep, fatigue, headaches;
- anemia. Other symptoms: fatigue and weakness, problems with concentration, sleep disturbances, appetite, decreased libido, headaches, tinnitus, pallor, palpitations;
- some types of food intolerances and food allergies. Other symptoms: disorders of the gastrointestinal tract (nausea, vomiting, diarrhea), skin manifestations of allergies;
- postinfectious asthenia. This is a state of constant fatigue and a desire to lie down to rest after any event, including after eating. It has been known for a long time — some people suffer from post-infectious asthenia after the usual flu, but they have become more talked about in the current pandemic. It turned out that COVID-19 often leads to the development of post-COVID syndrome.
If there are other symptoms that give cause for concern, you should consult a doctor and undergo an examination. It is possible that the problem can be solved by treating the underlying disease.
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Vigilance, alertness, or sustained attention: physiological basis and measurement. / Oken BS, Salinsky MC, Elsas SM. // Clinic Neurophysiol. - 2006 - 117(9)