In today’s fast-paced world, sleep problems are a global health concern. The WHO notes around 27% of people worldwide have sleep disorders, with 38.2% of Chinese adults experiencing insomnia—younger individuals often struggle with late nights, frequent dreams, and fragmented sleep. The link between diet and sleep quality is a growing focus in health research. While diets like the Mediterranean and ketogenic ones are tied to sleep, how daily diet directly impacts sleep within 24 hours remains unclear. A new study in Sleep Health by Columbia University Irving Medical Center researchers reveals a "temporal magic": more daytime fruits and vegetables significantly reduce nighttime sleep fragmentation. It fills gaps in understanding diet-sleep timing and offers practical guidance for "eating well to sleep well."
In the whirlwind of contemporary life, sleep problems have grown into a pressing global health issue. As per data from the World Health Organization, around 27% of the global population grapples with sleep disorders. In the United States, similar trends persist, with studies indicating that a significant portion of adults—especially younger generations—face challenges such as staying up late, restless sleep, and frequent disruptions during the night.
At the same time, the connection between "dietary choices" and "sleep quality" has become an increasingly popular subject in the field of health science. While diets like the Mediterranean diet and the ketogenic diet have been previously noted for their potential links to sleep patterns, the exact ways in which what we eat throughout the day directly influences our sleep at night has long been a mystery.
However, a groundbreaking study recently published in the journal Sleep Health has begun to unravel this enigma. Conducted by scientists from Columbia University Irving Medical Center and collaborating institutions, the research reveals a "temporal magic" between diet and sleep: higher intake of fruits and vegetables during the daytime is associated with a notable decrease in nighttime sleep fragmentation. This study not only addresses a long-standing gap in research on the time-ordered relationship between diet and sleep but also provides practical, science-backed advice for anyone looking to "improve their sleep through better eating."
The research team enlisted 34 young adults from the United States, with an average age of 28.3 years and an average BMI of 24.1 kg/m². Of these participants, 82.3% were male, and 50% identified as members of ethnic minority groups. All participants reported that they typically slept 7-9 hours per night and had no diagnosed sleep disorders. To collect data, each participant wore a wrist-worn actigraphy device to continuously monitor their sleep patterns. They also used the Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24) to record their daily food intake. In total, the study gathered 201 pairs of diet-sleep data points.
Fig. 1. (A) Associations between dietary intakes and sleep fragmentation index (SFI). Bar plot of regression coefficients (per 1 standard deviation increase in dietary measures to make effects on sleep fragmentation index more directly comparable) from linear mixed-effects models. Error bars represent +/- 1 SE. (B) Food groups and macronutrients with strongest effects on the SFI. Greater intake of carbohydrates and fruits and vegetables predicts lower SFI (better sleep quality). Trends were observed for higher fiber and lower red and processed meat intakes predicting lower SFI (better sleep quality).
Unlike traditional studies that rely on self-reported sleep quality, this research used the Sleep Fragmentation Index (SFI) as its core metric. SFI is calculated by dividing the number of nighttime awakenings by the total sleep time, providing a clear measure of how often sleep is interrupted. A lower SFI indicates more continuous sleep. For example, a person who wakes up 10 times during a total sleep time of 480 minutes would have an SFI of approximately 10/480 ≈ 2.08%.
Which Foods Are Secretly Improving Sleep?
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5 Cups of Fruits and Veggies = 16% Better Sleep Quality
The data analysis showed that for every additional cup of fruits and vegetables consumed during the day, the nighttime SFI decreased by 0.60 units (P=0.038). Even more striking: increasing fruit and vegetable intake from zero to the recommended daily amount of 5 cups was associated with an approximately 16% improvement in sleep quality. This is equivalent to eating 2 apples, 1 plate of broccoli, half a cucumber, and 1 cup of spinach salad each day—changes that can lead to a noticeable reduction in nighttime awakenings.
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The "Dual Nature" of Carbohydrates: Natural vs. Added Sugars
The study also found that natural carbohydrates—such as those found in whole grains and legumes—were significantly associated with a lower SFI (β=-0.016, P=0.022). In contrast, added sugars—common in milk tea, cakes, and other processed foods—had no beneficial effect on sleep (P=0.54). This means that starting the day with whole-grain bread and a banana is more likely to support better sleep that night than drinking sweetened soy milk.
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The "Hidden Conflict" Between Red Meat and Sleep
While the results did not reach statistical significance, the data suggested a trend: each additional ounce (about 28 grams) of processed meat—such as bacon or sausage—consumed during the day was associated with a potential 0.37-unit increase in nighttime SFI (P=0.098). This hints that frequently consumed processed foods like hamburgers and hot dogs may quietly disrupt the continuity of sleep.
How Do Fruits and Veggies Act as "Natural Sleep Aids"?
Why do fruits and vegetables have such a remarkable effect on regulating sleep? The study proposes three potential mechanisms:
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Natural Melatonin: A "Sleep-Promoting Signal"
Fruits and vegetables like tomatoes and cherries are rich in melatonin, a hormone that directly helps regulate the sleep-wake cycle. For example, drinking tart cherry juice has been shown to increase melatonin levels in the body and extend sleep duration.
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Polyphenols: Facilitating "Gut-Brain Communication"
Polyphenols—found in foods like blueberries and grapes—can improve the balance of gut bacteria. Through the "gut-brain axis," this balance may reduce inflammatory responses, thereby lowering the risk of sleep disruptions. -
Complex Carbs: A "Serotonin Factory"
The dietary fiber and carbohydrates in fruits and vegetables work together to promote the uptake of tryptophan into the brain. Tryptophan is then converted into serotonin, which is further synthesized into melatonin—another pathway through which these foods support better sleep.
In summary, this study is the first to reveal a direct temporal link between a healthy diet and improved nighttime sleep quality. While the sample size is relatively small and the participants were mostly young men, the findings provide strong preliminary evidence for future large-scale randomized controlled trials.
References:
Hedda L. Boege, Katherine D. Wilson, Jennifer M. Kilkus, et al. Higher daytime intake of fruits and vegetables predicts less disrupted nighttime sleep in younger adults, Sleep Health (2025). DOI:10.1016/j.sleh.2025.05.003