Study of the Impact of Nutrition on Sleep Quality

Features of the New Research

In this large-scale study, researchers examined the relationship between dietary habits and the quality of nighttime sleep. Unlike previous studies that relied on participants’ recollections of their diet and sleep, this research used mobile apps to record meals in real time and medical sensors for precise analysis of sleep phases.

Problems with Previous Approaches

Earlier, the connection between nutrition and sleep was assessed mainly through subjective data. Participants were asked to recall what they had eaten weeks or months before the experiment, which inevitably led to errors. Similar challenges arose in sleep assessment: fitness trackers and smartwatches could only record periods of wakefulness and sleep, but could not accurately determine sleep phases such as light, deep, or REM sleep. This limited the accuracy of conclusions about the quality of nighttime rest.

Research Methodology

The study involved over 3,500 adults with diverse lifestyles and habits, with an average age of 53. For two days, participants logged every meal in a mobile app immediately after eating to minimize memory errors. Before sleep, they wore medical devices that accurately recorded neurophysiological indicators to determine sleep phases. Additional sensors tracked snoring, blood oxygen levels, heart rate, and breathing patterns.

Based on the collected data, an algorithm calculated how much time each participant spent in different sleep phases: N1, N2 (light sleep), N3 (deep sleep), and REM (rapid eye movement sleep). The analysis also considered factors such as age, gender, caffeine intake, and dietary and sleep data from the previous day, allowing researchers to distinguish the effects of a single meal from long-term habits.

Main Results

The analysis showed that participants who consumed more fiber (an average of 21 grams per day, roughly equivalent to 2.5 cups of peas) spent more time in deep sleep (N3)—3.4% longer—and less time in light sleep (N1 and N2)—2.3% less—compared to others. This indicates a deeper and more restorative sleep.

Additionally, these participants had a nighttime heart rate that was one beat per minute lower, suggesting greater relaxation and more effective recovery of the cardiovascular system during sleep.

Possible Mechanisms

The reasons for fiber’s positive effect on sleep are not yet fully understood. It is believed that dietary fiber is processed by gut microbes into short-chain fatty acids, such as butyric acid, which reduce inflammation and alter signaling between the gut and brain, promoting deeper sleep.

Additional Observations

Participants whose diets included more than five types of fruits, vegetables, and nuts per day fell asleep faster and had lower nighttime heart rates. A varied plant-based diet provides the body with vitamins, minerals, and polyphenols, which reduce inflammation and help relax the nervous system, making it easier to transition to sleep.

Publication of Results

The study results have been published on the medical preprint portal medRxiv.