Americans love carb-heavy foods such as pasta, white bread, and baked goods. But all those carbohydrates and sugars might be keeping people up at night. About 30 percent of Americans have insomnia, and one study finds carb-heavy diets may be partly to blame, according to lead author James Gangwisch, assistant professor of clinical psychiatric social work at Columbia University in New York.

Highly refined sugars have a high glycemic index, which can trigger a sudden rise in blood sugar. “When blood sugar is raised quickly, your body reacts by releasing insulin, and the resulting drop in blood sugar can lead to the release of hormones such as adrenaline and cortisol, which can interfere with sleep,” Gangwisch explained.

On the other hand, a diet rich in vegetables, fiber, and whole fruit was linked to fewer problems with insomnia and better, restful sleep. Whole fruits contain sugar, but the fiber in them prevents spikes in blood sugar, Gangwisch explained.

“This suggests that the dietary culprit triggering insomnia was the highly processed foods that contain larger amounts of refined sugars that aren’t found naturally in food,” he said.