Association of plant-based diet index with sleep quality in middle-aged and older adults: The Healthy Dance Study.

OBJECTIVES: To investigate the association between plant-based diet indices and sleep quality in Chinese middle-aged and older adults. METHODS: The study included 2424 participants aged 45 years and older. Dietary data were collected using a semi-quantitative food frequency questionnaire, and sleep quality was assessed by the Pittsburgh Sleep Quality Index scale. Plant-based diet was categorized based on 3 indices (score range, 17-85) covering 17 food groups: the overall plant-based diet index, healthful plant-based diet index, and unhealthful plant-based diet index. The associations between these plant-based diet indices and sleep quality were examined using logistic and linear regression analyses. RESULTS: After controlling for sociodemographic, lifestyle, and multiple disease-related factors, participants in the highest quartile of the healthful plant-based diet index had 0.55 higher odds of better sleep quality (95% CI: 0.42, 0.72; Ptrend< .001). In contrast, participants in the highest quartile of the unhealthful plant-based diet index had 2.03 higher odds of poor sleep quality (95% CI: 1.51, 2.72; Ptrend< .001). In addition, plant-based diet index and healthful plant-based diet index were inversely associated with Pittsburgh Sleep Quality Index scores, while unhealthful plant-based diet index and Pittsburgh Sleep Quality Index scores were positively associated. CONCLUSIONS: We found unhealthy plant-based diets are significantly associated with poor sleep quality. Adherence to overall plant-based diets, especially healthy plant-based diets, was positively associated with optimal sleep quality.