A new study finds that postmenopausal women who eat a diet high in refined carbohydrates, particularly added sugars, may be at greater risk for insomnia. In contrast, women in the study who ate more vegetables, fiber, and whole fruits (not juice) were less likely to develop insomnia.
“Insomnia is often treated with cognitive behavioral therapy or medications, but these can be expensive or carry side effects,” said the study’s senior author James Gangwisch, Ph.D., assistant professor at Columbia University Vagelos College of Physicians and Surgeons.
“By identifying other factors that lead to insomnia, we may find straightforward and low-cost interventions with fewer potential side effects.”
The findings are published online in The American Journal of Clinical Nutrition.
Earlier studies have investigated the relationship between refined carbs and insomnia, but results have been mixed. And since the studies didn’t follow participants over time, it’s not clear if a diet that’s high in refined carbs triggered the onset of insomnia, or if insomnia caused individuals to eat more sweets.
In the current study, the researchers analyzed data from more than 50,000 participants in the Women’s Health Initiative who had completed food diaries. They looked at whether women with higher dietary glycemic index were more likely to develop insomnia.
They found that different types and amounts of carbs can increase blood sugar levels to varying degrees. In particular, highly refined carbohydrates — such as added sugars, white bread, white rice, and soda — have a higher glycemic index, and cause a more rapid increase 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 says.
The researchers hypothesized that the rapid spikes and drops in blood sugar after consuming refined carbs may trigger insomnia.
They discovered that the higher the dietary glycemic index, the greater the risk of developing insomnia. On the other hand, women who consumed more vegetables and whole fruits (not juices) were less likely to develop insomnia.
“Whole fruits contain sugar, but the fiber in them slow the rate of absorption to help prevent spikes in blood sugar,” Gangwisch said. “This suggests that the dietary culprit triggering the women’s insomnia was the highly processed foods that contain larger amounts of refined sugars that aren’t found naturally in food.”
Since most people — not just older women like those in the study — experience a rapid increase in blood sugar after eating refined carbs, the authors suspect that the findings may also hold true in a broader population.
“Based on our findings, we would need randomized clinical trials to determine if a dietary intervention, focused on increasing the consumption of whole foods and complex carbohydrates, could be used to prevent and treat insomnia,” said Gangwisch.