Scientists have linked fiber with good sleep. What doctors say

Scientists have found a link between the composition of the daily diet and how a person sleeps the next night. The work is published in the journal Nature Health, it is retold by The Washington Post.

What scientists have learned about fiber and sleep

The researchers analyzed data from 4,793 adult sleep nights: they recorded what they ate in real time, and wearable devices recorded sleep duration, its phases and night pulse.

The most noticeable link was found with fiber intake: the more dietary fiber was in the diet, the more time participants spent in deep and REM sleep (the REM phase), and the night heart rate was lower.

A similar effect was observed in a diet with a high proportion of plant foods - vegetables, fruits, whole grains, legumes, nuts and seeds. At the same time, individual vitamins and minerals, as well as the ratio of proteins, fats and carbohydrates, did not show a stable relationship with sleep quality.

The authors also note that a late, dense meal may increase sleep duration, but at the same time increase the night heart rate.

How much confidence in the research

“Statistical significance has been proven,” says Elena Tsareva, candidate of medical sciences, neurologist-somnologist, head of the somnological service “Unison”. The change itself is small – up to 1-1.5%, so it can be difficult to feel them in everyday life.

However, according to Tsareva, a small effect does not mean that nutrition is not important. Sleep depends on many factors at once, and the effect of each of them individually can be small. Nutrition, physical activity, stress and regimen with regular combination can give a more noticeable effect.

An important advantage of the work is a large amount of data and an objective assessment of sleep using wearable devices, says the executive director of the non-profit organization NRC “Healthy Nutrition”, nutritionist and gastroenterologist Nuria Dianova. However, she emphasizes that the authors recorded a correlation, not a direct cause-and-effect relationship. "It doesn't prove 100% that broccoli for dinner turns on deep sleep," she explains.

In addition, a number of factors that can simultaneously affect both nutrition and sleep were not included in the analysis. Among them Pisareva calls physical activity, stress level, alcohol consumption, body weight and metabolic health.

The queen proposes to divide external factors into those that promote sleep and those that support wakefulness. The first reduces the pulse, pressure, body temperature and anxiety level. If these indicators increase, it is more difficult for the body to go to sleep. Therefore, the night pulse, which the researchers assessed, may be one indicator of how calm the body recovers at night.

Why fiber can affect sleep quality

“Fiber works in several ways at once: it slows the absorption of sugars, preventing nocturnal glucose jumps, serves as food for beneficial gut bacteria and helps reduce the level of systemic inflammation, which is directly related to breathing disorders in sleep,” emphasizes gastroenterologist Dianova.

Somnologist Tsarev also emphasizes that the nature of food affects the intestinal microflora, and digestive disorders affect the quality of sleep. She emphasizes that the restructuring of the microflora does not occur in one day, so the impact of regular nutrition can be more noticeable at a distance of several weeks.

Do you need to eat fiber in the evening

According to the gastroenterologist Dianova, for sleep, there is no fundamental difference in the time of taking fiber, it is recommended to eat 25-30 g of fiber per day.

“Morning and afternoon are ideal times for the bulk of fiber, as it gives a long feeling of fullness, stabilizes blood sugar during the day and prevents evening bouts of hunger.” In the evening, a moderate amount of soft, heat-treated fiber (stewed vegetables, a small amount of berries) is useful, but a large portion of raw cabbage, legumes or bran right before bedtime can cause bloating, she notes.

Pisareva also advises to increase the amount of fiber gradually, especially for people prone to bloating and digestive disorders. In such cases, vegetables are better consumed heat-treated and distribute fiber sources between several meals.

Somnologist Tsarev also warns that there is no universal recommendation to eat more fiber in the evening: if digestion is disturbed, its excess can, on the contrary, cause discomfort and interfere with sleep.

What can be changed in the diet

“Increasing fiber in plant diversity is like a good potential diet for those who want to sleep well.” But it’s not a substitute for stress and physical activity. These factors - they are also important for a comfortable sleep, emphasizes nutritionist Pisareva.

Dietitian Dianova also emphasizes that for deeper sleep, you need to make sure that vegetable salad or stew are garnished in dinner, rather than an additional portion of potatoes or pasta. "This is the rare case where the nutritional recommendation is both beneficial for the heart, gut, metabolism and nervous system," she added.