Make this one diet change during the day to sleep better at night

A small new study led by researchers at UChicago Medicine and Columbia University found that eating more fruits and vegetables during the day was associated with better sleep at night.

“Dietary modifications could be a new, natural, and cost-effective approach to achieve better sleep,” said co-senior author Esra Tasali, MD, director of the UChicago Sleep Center in a UChicago write-up on the study.

While research already shows that sleep can impact what you eat, with poor sleep causing people to reach for unhealthier foods higher in fat and sugar, the relationship appears to go both ways. Previous research has associated high fruit and vegetable intakes with better overall sleep quality—but this new study is the first to establish a connection between daytime dietary choices and sleep quality that same night.

The study looked at self-reported food consumption and sleep data from a wrist monitor of 34 healthy U.S. adults ages 21 to 35 who regularly sleep seven to nine hours a night. They were specifically looking at “sleep fragmentation,” which refers to how often someone wakes up or shifts from deep to light sleep throughout the night.

Researchers found that increasing dietary intake of fruits and vegetables from zero to five cups per day—the Centers for Disease Control’s recommendation—was associated with 16% better sleep quality, with participants experiencing deeper, less interrupted sleep that same night. A similar association was found for eating more complex carbohydrates like whole grains as well. Those who ate higher intakes of red and processed meat, however, had more disrupted sleep. 

“People are always asking me if there are things they can eat that will help them sleep better,” coauthor Marie-Pierre St-Onge, PhD, director of the Center of Excellence for Sleep & Circadian Research at Columbia, told UChicago. “Small changes can impact sleep. That is empowering—better rest is within your control.”

How to increase your fruit and vegetable intake

The CDC estimates that only 12% of U.S. adults meet the recommended 1.5 to 2 cups of fruits per day, and only 10% are hitting the recommended 2 to 3 cups of vegetables per day. But it can be tricky to visualize what exactly that might look like if you’re not measuring out a cup of berries.

The Department of Agriculture says the following are all equivalent to one cup (so double it for fruits and double or triple it for vegetables):

• 1 large banana
• ½ cup of dried fruit
• 32 red seedless grapes
• 1 cup of 100% juice
• 12 baby carrots
• 1 large sweet potato
• 2 cups of raw spinach
• 1 cup of cooked black beans

If you’re struggling to up your fruit, veggie, and complex carbohydrate intake, here are tips nutrition experts shared with Fortune:

• Swap out animal proteins for plant-based ones, such as chickpeas, lentils, or beans, in meals like curries or stews.
• Put more beans and corn into your favorite chili.
• Fill half your plate with vegetables, or try to add one extra serving of vegetables to every meal.
• Swap whole grains for refined carbohydrates, like bulgur or barley in place of white rice, or whole-grain bread for white bread, for example.