Associations between self-reported sleep duration and abnormal serum lipids in eastern China: a population-based cross-sectional survey

To evaluate the associations between sleep duration and total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). The present study included 60,283 adults aged ≥18 years from the Chronic Disease and Risk Factor Surveillance in Nanjing. Generalized additive model (GAM) with forward stepwise selection method was used to analyze the nonlinear relationships between sleep duration and abnormal serum lipids. The reported effective degree of freedom (EDF) values in GAM indicates the degree of smooth curvature. EDF = 1 is a sign of linear correlation between predictors and outcome. EDF >1 is the sign of a more complex relationship between sleep duration and abnormal serum lipids. The evaluation of interaction of sex and sleep duration by using multivariable GAM revealed a U-shaped correlation between sleep duration and dyslipidemia (EDF = 4.60, P < 0.001), high TC (EDF = 3.38, P < 0.001), and high LDL-C (EDF = 3.67, P < 0.001) in male, and a U-shaped correlation between sleep duration and dyslipidemia (EDF = 4.69, P < 0.001), high TC (EDF = 3.33, P < 0.001), and high LDL-C (EDF = 3.21, P < 0.001) in female. There was a U-shaped correlation between sleep duration and high TG in male (EDF = 3.84, P < 0.001) and semi-linear correlation in female (EDF = 1.82, P = 0.028). Moreover, there was a linear correlation between sleep duration and low HDL-C in men (EDF = 1.04, P = 0.002), but no significant correlation in women (EDF = 3.18, P = 0.080). Both shorter and longer sleep durations were associated with abnormal serum lipid profiles in men and women.