Sleep, 24-hour activity rhythms, and cardiometabolic risk factors in school-age children
- S-Med
- Sep 10
- 2 min read
In this large population-based cross-sectional study we observed that nightly awakenings and intradaily variability of the 24-hour activity rhythm were associated with body fat and glucose concentrations already at school age. The associations of fewer awakenings with lower glucose and higher IV with higher FMI and visceral fat mass were only prevalent among boys. Sleep and 24-hour rhythm patterns were not associated with other cardiometabolic risk factors.
For sleep measures we observed associations of more awakenings with higher glucose concentrations but with lower BMI. Although there are very few studies that included nightly awakenings with which to make comparisons, the observed association with BMI was in the opposite direction to that expected and compared to a recent actigraphic study in 676 children aged 5–6 years in Poland.These conflicting results might be explained by the different type and location of actigraph used (ActiGraph on hip), younger age, or higher prevalence of overweight. Moreover, the number of awakenings in our study may be overestimated: actigraphs are known to have poor specificity to detect wake periods, because data on sleep/wake are based on movement only.Therefore, we chose to only assess periods containing at least 5 consecutive minutes of movement as an awakening. However, the observed negative association between awakenings and BMI might still (partly) be driven by increased physical movement during sleep rather than actual sleep disruptions. This may explain why we, similar to previous pediatric studies, did not observe any association between wake after sleep onset (minutes) and adiposity. Recent studies proposed including parameters of nightly movement in pediatric sleep actigraphy studies, such as mean activity count or activity index The observed discrepancy in association of more nightly awakenings with lower BMI but higher glucose concentrations is remarkable and needs further investigation. We observed suggestive evidence, which attenuated after multiple testing adjustment, for the associations of sleep duration with BMI and visceral fat mass among girls. This finding is consistent with previously reported associations of shorter sleep duration with increased BMI and FMI (dual-energy X-ray absorptiometry) in adolescents of both sexes. Yet, associations are not as strong as reported in adults, suggesting the association of sleep duration with adiposity might become stronger at older ages. Further follow-up studies are needed to assess this difference between childhood and adolescence and between sexes.
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