A study has found that post-menopausal women who consumed a diet high in refined carbohydrates – particularly added sugars – were more likely to develop insomnia. Women whose diet included higher amounts of vegetables, fibre, and whole fruit (not juice) were less likely to develop problems with insomnia.
“Insomnia is often treated with cognitive behavioural therapy or medications, but these can be expensive or carry side effects,” says the study’s senior author Dr James Gangwisch, 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.”
Previous studies have explored a possible link between refined carbohydrates and insomnia, but results have been inconsistent. And because the studies didn’t follow individuals 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.
One way to determine if carb intake is causing sleep problems is to look for the emergence of insomnia in people with different diets. In the current study, Gangwisch and his team gathered data from more than 50,000 participants in the Women’s Health Initiative who had completed food diaries. The researchers looked at whether women with higher dietary glycaemic index were more likely to develop insomnia.
Different kinds and amounts of carbohydrates increase blood sugar levels to varying degrees. Highly refined carbohydrates – such as added sugars, white bread, white rice, and soda – have a higher glycaemic 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 hypothesised that the rapid spikes and troughs in blood sugar after eating refined carbs may trigger insomnia. They found that the higher the dietary glycaemic index – particularly when fuelled by the consumption of added sugars and processed grains – the greater the risk of developing insomnia. They also discovered that women who consumed more vegetables and whole fruits (not juices) were less likely to develop insomnia.
“Whole fruits contain sugar, but the fibre in them slow the rate of absorption to help prevent spikes in blood sugar,” says Gangwisch. “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 postmenopausal women, experience a rapid rise in blood sugar after eating refined carbohydrates, the authors suspect that these findings may also hold true in a broader population.
“Based on our findings, we would need randomised 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,” says Gangwisch.
Background: Previous studies have shown mixed results on the association between carbohydrate intake and insomnia. However, any influence that refined carbohydrates have on risk of insomnia is likely commensurate with their relative contribution to the overall diet, so studies are needed that measure overall dietary glycemic index (GI), glycemic load, and intakes of specific types of carbohydrates.
Objective: We hypothesized that higher GI and glycemic load would be associated with greater odds of insomnia prevalence and incidence.
Methods: This was a prospective cohort study with postmenopausal women who participated in the Women’s Health Initiative Observational Study, investigating the relations of GI, glycemic load, other carbohydrate measures (added sugars, starch, total carbohydrate), dietary fiber, and specific carbohydrate-containing foods (whole grains, nonwhole/refined grains, nonjuice fruits, vegetables, dairy products) with odds of insomnia at baseline (between 1994 and 1998; n = 77,860) and after 3 y of follow-up (between 1997 and 2001; n = 53,069).
Results: In cross-sectional and longitudinal analyses, higher dietary GI was associated with increasing odds of prevalent (fifth compared with first quintile OR: 1.11; CI: 1.05, 1.16; P-trend = 0.0014) and incident (fifth compared with first quintile OR: 1.16; CI: 1.08, 1.25; P-trend < 0.0001) insomnia in fully adjusted models. Higher intakes of dietary added sugars, starch, and nonwhole/refined grains were each associated with higher odds of incident insomnia. By contrast, higher nonjuice fruit and vegetable intakes were significantly associated with lower odds of incident insomnia. Also, higher intakes of dietary fiber, whole grains, nonjuice fruit, and vegetables were significantly associated with lower odds of prevalent insomnia.
Conclusions: The results suggest that high-GI diets could be a risk factor for insomnia in postmenopausal women. Substitution of high-GI foods with minimally processed, whole, fiber-rich carbohydrates should be evaluated as potential treatments of, and primary preventive measures for, insomnia in postmenopausal women.
James E Gangwisch, Lauren Hale, Marie-Pierre St-Onge, Lydia Choi, Erin S LeBlanc, Dolores Malaspina, Mark G Opler, Aladdin H Shadyab, James M Shikany, Linda Snetselaar, Oleg Zaslavsky, Dorothy Lane