Fiber-Rich, Plant-Forward Diet Linked to Better Sleep

Day-to-day dietary choices may have measurable effects on nighttime sleep, according to a new study published in Nature Health.

Routine daily dietary choices, particularly plant-forward composition and meal timing, have immediate and measurable effects on objective sleep architecture.– Researchers, Weizmann Institute of Science

The research found that diets higher in fiber and plant-based foods were associated with more restorative sleep and lower nighttime heart rates, while the timing and size of evening meals also appeared to influence sleep physiology.

Researchers analyzed 4,793 person-nights of data from 3,598 healthy adults, combining real-time dietary logs with wearable recordings that measured sleep stages and nocturnal heart rate under normal living conditions.

Higher fiber density was associated with increases in deep and rapid eye movement (REM) sleep, reductions in light sleep and an average decrease of 1.14 beats per minute in nighttime heart rate.

Greater plant diversity — defined as the number of unique plant foods consumed each day — and higher consumption of whole plant foods were also associated with lower nocturnal heart rates.

The findings add to a growing body of research into the relationship between plant-rich diets and sleep, as well as other measures of metabolic and cardiovascular health.

Meal timing also appeared to play a significant role.

Heavier evening meals, measured by the percentage of daily calories consumed during the six hours before bedtime, were associated with an average 7.7 minutes of additional sleep.

However, those meals were also associated with a 0.73-beat-per-minute increase in nighttime heart rate, suggesting that longer sleep did not necessarily correspond with more favorable physiological conditions during the night.

The researchers also found that diets with a higher Dietary Phytochemical Index, a measure reflecting the proportion of calories derived from phytochemical-rich plant foods, were associated with more REM sleep, less light sleep and lower nighttime heart rates.

By contrast, short-term differences in the proportion of calories derived from carbohydrates, proteins and fats, as well as micronutrient intake, did not show robust associations after statistical correction.

“Routine daily dietary choices, particularly plant-forward composition and meal timing, have immediate and measurable effects on objective sleep architecture,” the researchers wrote.

Nutrition experts said the findings do not point to a specific “sleep diet,” but are broadly consistent with eating patterns associated with the Mediterranean diet.

Registered dietitian Dalhia Campbell told The Guardian that a balanced diet emphasizing fruits, vegetables, whole grains, lean proteins and healthy fats may help support energy regulation and hormones involved in sleep.

Marie-Pierre St-Onge, an associate professor of nutritional medicine at Columbia University, said some of the potential benefits of Mediterranean-style eating may stem from the anti-inflammatory and antioxidant compounds in plant foods, as well as nutrients that support the gut microbiome.

Previous research has also identified links between Mediterranean dietary patterns and sleep.

A 2024 systematic review of 23 studies found that greater adherence to the Mediterranean diet was generally associated with a lower likelihood of poor sleep quality, inadequate sleep duration, excessive daytime sleepiness and symptoms of insomnia.

While most of the studies were conducted in the Mediterranean basin, research in other regions also found associations between Mediterranean-style eating and sleep quality, suggesting that underlying biological mechanisms may contribute to the relationship.

However, the review’s authors cautioned that the evidence was largely observational and that the relationship could be bidirectional, with diet affecting sleep and sleep habits potentially influencing food choices.

A 2022 study previously reported by Olive Oil Times also found that medium or high adherence to the Mediterranean diet was associated with better sleep among university students.

Consumption of ultra-processed foods, meanwhile, has been associated in other research with poorer sleep quality and a higher prevalence of insomnia.

Experts cautioned that increasing fiber intake alone should not be regarded as a treatment for poor sleep. Instead, the findings reinforce the importance of considering overall diet quality, including greater consumption of fruits, vegetables and other minimally processed plant foods.