Abstract
BACKGROUND: Hyperlipidemia is closely associated with chronic low-grade inflammation and metabolic disorders. The Dietary Inflammatory Index (DII) reflects the pro-inflammatory potential of the diet, but its association with sleep disorders among individuals with hyperlipidemia remains unclear. This study aims to explore the association between DII and sleep disorders in adults with hyperlipidemia and analyze the mediating effect of body mass index (BMI). METHODS: Data from 13,195 participants with hyperlipidemia from the National Health and Nutrition Examination Survey (NHANES) in the United States (2007-2018) were included. Sleep disorders were defined based on self-reported physician diagnosis. DII scores were calculated based on 22 dietary components. Weighted multivariable logistic regression, restricted cubic splines, curve fitting models, and threshold analysis were used to evaluate the association between DII and sleep disorders. Finally, the mediating effect of BMI was analyzed. RESULTS: A total of 13,195 participants were included, of whom 1,598 reported sleep disorders. After adjusting for all covariates using weighted logistic regression, each 1-unit increase in DII was associated with a 5.7% higher prevalence of sleep disorders (odds ratio [OR] = 1.057, 95% confidence interval [CI]: 1.012-1.105). When DII was categorized into four groups, the OR for Q4 versus Q1 was 1.295 (95% CI: 1.039-1.614, P = 0.0269), with a significant trend (trend test P < 0.05). Restricted cubic spline and curve fitting models showed a linear relationship between DII and sleep disorder prevalence. Subgroup analysis indicated a stronger association between DII and sleep disorders among participants with hyperlipidemia who were under 60 years old. Mediation analysis further revealed that BMI mediated 26.07% of the association between DII and sleep disorders (P < 0.05). CONCLUSION: The results of this cross-sectional study show a positive association between pro-inflammatory diets and the risk of sleep disorders in patients with hyperlipidemia. A significant trend was observed across the quartiles of the Dietary Inflammatory Index (DII). The adjusted odds ratio (OR) for the highest quartile (Q4) compared with the lowest quartile (Q1) was 1.295 (95% confidence interval [CI]: 1.039-1.614, P = 0.0269), which was particularly evident in the young and middle-aged population (< 60 years old). Reducing the dietary inflammatory index may improve sleep health through weight loss (mediated by BMI) and direct anti-inflammatory effects. Future interventional studies are needed to clarify the causal impact of dietary inflammation regulation on sleep quality and the underlying molecular mechanisms, so as to provide a scientific basis for precision nutritional intervention.