What you eat affects your sleep

Some foods have an obvious impact on sleep. It’s no surprise, for example, that drinking too much caffeine or alcohol can cause you to toss and turn at night. But in recent years, scientists have discovered that certain foods and dietary patterns may help you fall asleep faster and sleep more soundly.

Most of the emerging evidence indicates that you can improve the quality of your nightly sleep by following a diet that’s relatively high in protein, fibre, fruits and vegetables and low in saturated fat and added sugars. This approach to eating largely fits with the Mediterranean diet. St-Onge and her colleagues have found in large observational studies that people whose diets closely adhere to the Mediterranean diet tend to sleep longer at night and experience fewer symptoms of insomnia.

Randomised controlled trials, in which scientists tell people what to eat and then look for changes in their sleep, are less common. But small, rigorous trials have found that people get more deep, restorative sleep when they’re instructed to eat more fibre from fruits, vegetables and other plants.

In the latest study, scientists set out to see how various foods that people eat throughout the day would influence their nightly sleep. The participants were part of a long-running digital health study known as the Human Phenotype Project, which has so far enrolled 28,000 people.

The scientists carrying out the study have spent years collecting extensive data on the participants, including their medical histories, diet and lifestyle habits. They’ve also tracked their blood sugar levels using continuous glucose monitors, analysed their genetics and gut microbiomes, and monitored their sleep using sleep-tracking devices.

How plant-based diets impact sleep

The researchers looked at 32 dietary factors to see whether they impacted people’s sleep, ranging from their vitamin and mineral intake to the timing of their meals, their daily calorie consumption and their plant intake. They found that seven factors were associated with one or more aspects of nightly sleep.

Eating a more fibre-dense diet during the day was linked to more restorative sleep, including more deep sleep. It was also associated with more REM (rapid eye movement) sleep, which is the stage of sleep where new memories are consolidated and where vivid dreams occur. The researchers found that eating a greater variety of plant foods, and in particular minimally processed ones such as beans, lentils, nuts, fruits and vegetables, were both associated with a lower night-time heart rate, which is a sign of healthy rest and recovery.

The researchers also looked at the dietary phytochemical index, which measures the percentage of calories in a person’s diet that come from foods high in phytochemicals that promote health, such as beta-carotene, lycopene and resveratrol. These phytochemicals are antioxidants and other natural compounds from plants that help fight inflammation and lower disease risk.

The scientists found that people whose diets were high in phytochemicals tended to get more deep sleep at night. They had more REM sleep, lower night-time heart rates and decreased levels of light sleep.

“Fibre- and plant-forward diets have a very positive effect on your sleep architecture,” said Hagai Rossman, an author of the study and an assistant professor at Mohamed bin Zayed University of Artificial Intelligence in the United Arab Emirates. “That was a significant finding. This has been pretty well known, but now we’ve shown it in a large and free-living population.”

One peculiar finding was that eating heavier evening meals was linked to a slightly longer sleep duration. Many sleep experts recommend that people eat light dinners to avoid experiencing acid reflux, heartburn and sleep disruptions. The researchers found that even though eating a larger evening meal was associated with longer sleep, it also appeared to increase night-time heart rate, which could mean poorer-quality sleep.

“Heavier meals that are not too close to bedtime may not have an adverse impact on sleep duration and may allow you to sleep longer,” St-Onge said. “You might be woken up earlier if you get hungry in the early-morning hours.”

But the higher night-time heart rate, she added, “shows that this longer sleep may not be as restorative”.

What to eat for better sleep

Ultimately, the new study adds to the growing body of evidence that plant-based diets may help you sleep better – and there are a number of reasons for this. St-Onge pointed out that fruits and vegetables contain compounds that can bind to GABA receptors in the brain. This can have a calming effect on the brain and the nervous system, which makes it easier to fall asleep at night.

“It’s also possible that people who eat a more plant-forward diet in general have a different gut microbiome composition that produces more short-chain fatty acids that interact with neurotransmitter signalling involved in sleep promotion,” she added.

St-Onge published a book in 2025, Eat Better, Sleep Better, that explains how your diet affects your sleep and which foods you should eat throughout the day to get an optimal amount of sleep-promoting nutrients, such as protein, fibre, tryptophan, melatonin and serotonin.

In her book, St-Onge recommends breakfasts such as quiche with salmon, goat cheese and spinach or plain yoghurt with muesli. For lunch, she suggests a turkey and black bean burrito bowl or a salad with tuna, chickpeas and sesame-ginger vinaigrette. And for dinner, she advises meals such as garlic shrimp with a fresh salad or chickpea pasta with butternut squash, walnuts, parmesan and oven-roasted broccoli.

The idea is to fill your plate with plant foods, not to cut out all animal foods.

Here are a few more examples of plant-based foods that are rich in phytochemicals: