The dietary factors associated with sleep duration in postmenopausal middle-aged women: a cross-sectional study using 2019-2023 Korea National Health and Nutrition Examination Survey data.

Objectives: This study aimed to analyze dietary factors associated with sleep duration in postmenopausal middle-aged women using data from the Korea National Health and Nutrition Examination Survey (KNHANES), with particular emphasis on the postmenopausal period.

Methods: A total of 3,040 postmenopausal women aged 40-64 years from the 2019-2023 KNHANES were included. Sleep duration was classified into four categories: "appropriate sleep duration" (ASD; 7-9 hours), "short sleep duration" (6-7 hours), "very short sleep duration" (VSSD; < 6 hours), and "long sleep duration" (LSD; > 9 hours). Nutrient and food intake were compared among groups using analysis of covariance. Multinomial logistic and polynomial regression models assessed associations, adjusting for demographic and health covariates.

Results: The VSSD group had higher body mass index and waist circumference than the ASD group, despite lower total energy intake, and also consumed more snack energy and skipped breakfast and dinner more often. This group also had lower intakes of monounsaturated fatty acids and nuts and seeds. In the late menopausal group, greater consumption of cereal grains, fish and shellfish, and beverages was associated with elevated LSD risk. Conversely, higher folate intake in the early menopausal group was inversely associated with VSSD risk. Cholesterol intake was positively associated with LSD risk in both groups. A negative nonlinear association between sleep duration and dietary intake was observed in the early menopausal group when polyunsaturated fatty acid intake exceeded 19.86 g/day and riboflavin intake exceeded 1.76 mg/day. In the late menopausal group, riboflavin intake was strongly correlated with increased LSD risk (odds ratio = 4.776, P = 0.004). Sugar and beverage intake showed a positive linear relationship with sleep duration at average intake levels.

Conclusion: Dietary factors associated with sleep duration differed by postmenopausal period, with specific nutrients and food groups exhibiting variable associations with sleep duration above mean intake levels.