Association of sleep characteristics with adiposity markers in children.

Background Accumulating evidence suggests a relationship between sleep alterations and overweight/obesity in children. Our aim was to investigate the association of sleep measures other than obstructive sleep apnea or sleep duration with overweight/obesity and metabolic function in children. Methods We conducted a prospective cohort study in school- aged children (aged 5 to 8 years, prepubertal, and 12 to 15 years, pubertal) with overweight/obesity and normal-weight children. All children underwent a standardized in-laboratory polysomnography followed by a fasting blood assessment for glucose and metabolic testing. Subjective sleep measures were investigated by a 7-day sleep diary and questionnaire. We analyzed prepubertal and pubertal groups separately using logistic regression and partial correlation analyses. Results A total of 151 participants were analyzed. Overweight/obese children had significantly higher odds for arousal index (prepubertal children: 1.28, Confidence interval (CI): 1.06, 1.67; pubertal children: 1.65, CI: 1.19, 2.29) than normal-weight children, independent of age and gender. In prepubertal children, arousal-index was positively associated with C-peptide (r=0.30, p=0.01), whereas Minimum O2 saturation was negatively associated with triglycerides (r=-0.34, p=0.005), adjusting for age and sex. However, associations were attenuated by further adjustment for body mass index standard deviation scores (BMI-SDS). In pubertal children, higher level of apnea-hypopnea-index and pCO2 predicted increased lipoprotein (a) levels (r=0.35, p=0.03 and r=0.40, p=0.01, respectively), independent of age, sex, and BMI-SDS. A negative association was found between pCO2 and high-density lipoprotein (HDL)-cholesterol (r=-0.40, p=0.01). Conclusions Overall, we report that sleep quality as measured by arousal index may be compromised by overweight and obesity in children and warrants attention in future intervention programs.

Nocturnal levels of chemerin and progranulin in adolescents: influence of sex, body mass index, glucose metabolism and sleep.

BACKGROUND: Adipokines have been implicated in obesity, insulin resistance and sleep regulation. However, the role of chemerin and progranulin, two recently described adipokines, in the context of sleep remains unclear. The aim of this study was to compare nocturnal serum chemerin and progranulin levels between overweight/obese and normal-weight adolescents and to assess variations by sex, across different sleep stages and in relation to glucose metabolism. METHODS: The study sample included 34 overweight/obese and 32 normal-weight adolescents from secondary schools and the Leipzig Research Center for Civilization Diseases (LIFE) Child study cohort. We obtained longitudinal serum adipokine levels during in-laboratory polysomnography followed by an oral glucose tolerance test. RESULTS: Overweight/obese adolescents had significantly higher mean nocturnal serum chemerin area under the curve (AUC) levels (348.2±133.3 vs. 241.7±67.7 vs. ng/mL×h, p<0.001) compared to normal-weight controls. In detail, higher chemerin AUC levels in obese/overweight subjects were exclusively due to increased levels in females. No overall difference for serum progranulin AUC was found between the groups. However, when assessing sex-specific levels, serum progranulin AUC levels were ~30% higher in overweight/obese males compared to overweight/obese females. Of note, nocturnal serum chemerin and progranulin AUC did not exhibit a correlation with markers of glucose metabolism or sleep stages. CONCLUSIONS: Collectively, we report a sexual dimorphism in nocturnal progranulin and chemerin levels, which may help explain underlying differences in energy balance and body composition between males and females in the context of obesity.