Daytime nap and nighttime sleep duration in relation to dyslipidemia among type 2 diabetes patients in eastern China: a cross-sectional study.

OBJECTIVES

To investigate associations of daytime nap and nighttime sleep duration with dyslipidemia among patients with type 2 diabetes (T2DM) in Eastern China.

METHODS

This investigation was conducted in Zhejiang Province, China, from March to November 2018. Multivariable logistic regression assessed associations of daytime nap and nighttime sleep duration with dyslipidemia. Restricted cubic spline (RCS) analyses using continuous sleep variables examined dose-response relationships. Sensitivity analyses (medication adjustment, reference category redefinition, modified Poisson regression) tested the robustness of the findings. Exploratory analyses evaluated individual lipid abnormalities. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated after confounder adjustment.

RESULTS

The study included 1,749 patients with T2DM, of whom 53.69% were classified as having dyslipidemia. In the fully adjusted logistic regression model, each standard deviation (SD) increment in daytime nap duration was significantly associated with 13% higher odds of dyslipidemia (OR = 1.13, 95% CI: 1.02-1.26). Compared with 1-30 min of daytime nap, >90 min was associated with 65% higher odds of dyslipidemia (OR = 1.65, 95% CI: 1.12-2.43). RCS analyses suggested a linear association between daytime nap duration and dyslipidemia (p for non-linearity > 0.05). For nighttime sleep duration, compared with >6-7 h, both <5 h and >8 h were associated with higher odds of dyslipidemia (OR = 2.16, 95% CI: 1.23-3.79 and OR = 1.50, 95% CI: 1.02-2.20, respectively). No significant association was observed for per-SD increment in nighttime sleep duration. RCS analyses demonstrated a significant U-shaped association between nighttime sleep duration and dyslipidemia. In exploratory analyses, prolonged daytime napping was associated with hypercholesterolemia, hypertriglyceridemia, and low HDL-C, whereas short nighttime sleep was primarily linked to hypertriglyceridemia and low HDL-C. Results from multiple sensitivity analyses were consistent with the primary findings, supporting the robustness of the observed associations.

CONCLUSION

Among patients with T2DM, longer daytime nap duration and both short and long nighttime sleep duration were associated with higher odds of dyslipidemia, with distinct linear and U-shaped patterns. These sleep behaviors were associated with differences in specific lipid fractions, warranting further prospective investigation.