What can you eat at night?

There is a well-known dietary myth that you can’t eat at night, that the gastrointestinal tract, pancreas and digestive organs don’t work as they should during sleep and at night.

So, there are two reviews with a total number of sources of about 150 studies on this issue. I don’t see the point in quoting them in full, I’ll voice them in a thesis. That is, the most important and a little bit.

The general meaning from both studies is that, yes, naturally, during sleep the following occurs: decreased salivation, frequency of swallowing, decreased pressure of the upper esophageal sphincter, and the number of primary contractions of the esophagus, but all this does not have any pathological character, so that we can say that the gastrointestinal tract at night is not able to normally cope with food entering the stomach before sleep.

As for gastric emptying, this characteristic most likely depends on individual circadian rhythms, and not on the fact of the presence or absence of sleep as such. So there is evidence that gastric emptying increases during the REM phase of sleep and slows down during the deep phase of sleep, and there is evidence that emptying slows down in both phases of sleep. Experiments with solid food have shown that gastric emptying occurs faster at night than in the morning.

Secretion of gastric juice, again, depends on individual circadian rhythms, and the highest secretion is observed between 10 p.m. and 2 a.m., regardless of whether a person is sleeping or not. At the moment, there is no evidence confirming that sleep affects the secretion of gastric juice. And in this process, the normal secretion of the hormone melatonin is of considerable importance, since melatonin inhibits the release of gastric acid, helps to normalize gastric blood flow, improves regeneration and affects the development of gastric mucosa, and the height of the villi, the overall thickness of the mucosa and cell division.

Peristalsis of the small intestine is even higher at night than during the day. And intestinal peristalsis itself can affect sleep, i.e. when drowsiness appears after eating (it doesn't matter, in the evening, during the day...), this can also happen due to signals sent by the central nervous system during intestinal stretching, and the accompanying secretion of the hormone cholecystokinin.

No relationship was found between food intake, sleep and negative changes in the secretion of gastrin, neurotensin, peptide YY, pancreatic hormones, polypeptide, amylase and protease. That is, this process does not depend on sleep phases or sleep as such in principle, but is tied to food intake and its digestion/assimilation.

And there is also such a concept as the adaptation of the body to systematically repeating conditions, i.e. if we are used to eating at night, then the body adapts to such a meal and launches the necessary chains of reactions so that the process goes as it should. And anticipating the desire of someone to accuse me of promoting getting drunk at night, I will immediately say that everything is as usual here, I am considering the situation of reasonable dietary control over the target caloric content of my balanced diet. But even if we do not take this important factor into account, purely from a physiological point of view, the gastrointestinal tract, pancreas and digestive organs work as they are supposed to within the framework necessary to perform their functions, both during wakefulness and during sleep / at night.

If we generalize the available scientific data, we can say that the rate of metabolic reactions associated with the metabolism of nutrients entering the body, in total during all phases of sleep, approximately corresponds to the rate of metabolic reactions during the period of wakefulness. Yes, in some phases of sleep, the rate of metabolic reactions is lower, but in the phases of rapid sleep, on the contrary, it is higher than during periods of wakefulness, i.e. as a result, the night metabolism in average indicators is leveled out (since it consists of periods of a decrease in the rate of metabolic reactions and their increase during sleep).

Style summary

In general, as can be seen from the presented data, nothing there during sleep is dramatically slowed down in terms of metabolic reactions associated with, among other things, the absorption of food, just as digestion and the hormonal system around digestion work quite briskly. And the existing regular physical activity during the day/week and control over incoming nutrients and target caloric content allow for an even more favorable effect on all these processes and the expenditure of energy calories.

So you can eat at night without harming your body. However, remember that nighttime meals are extra calories that are bad for your figure.