The association of sleep duration and cardiometabolic risk factors in a national sample of children and adolescents: the CASPIAN III study.

Objectives: Although sleep duration is one of the most important health-related factors, its association with risk factors for chronic diseases has not been completely clarified, especially among children and adolescents. The aim of this study was to evaluate the association between sleep duration and CVD risk factors among a nationally representative sample of Iranian children and adolescents.

Methods: This cross-sectional national study was performed on a representative sample of 5528 Iranian students, ages 10 to 18 y living in central cities of 27 provinces of Iran. Physical examinations and laboratory tests were performed using standard protocols. To determine the association between sleep duration and cardiometabolic risk factors, multivariable logistic regression was used and odds ratios (OR; with 95% confidence intervals) are reported.

Results: The mean ± SD age was not significantly different among boys (14.69 ± 2.45 y) and girls (14.7 ± 2.38 y). In a crude model, boys who slept > 8 h and 5 to 8 h had lower OR for abdominal obesity compared with those who had slept <5 h in a crude model (ORs, 0.70, 0.80, 1.0, respectively; P = 0.008). A similar result was observed in an age- adjusted model for the prevalence of abdominal obesity (ORs, 0.69, 0.76, 1.0, respectively; P = 0.011). Girls who had slept > 8 h per day had lower OR for high serum low-density lipoprotein levels compared with those who slept < 5 h per day (P = 0.002). These differences remained significant even in the fully adjusted model for all the confounding variables (P = 0.008). Moreover, among boys ages 10 to 14 y, longer sleep duration increased the risk for high total cholesterol in all models.

Conclusion: Shorter sleep duration increased the risk for some cardiometabolic risk factors among adolescents. The clinical significance of our findings should be determined in longitudinal studies.