BACKGROUND/OBJECTIVES Although sleep duration is well established as a risk factor for child obesity, how measures of sleep quality relate to body size is less certain. The aim of this study was to determine how objectively measured sleep duration, sleep timing, and sleep quality were related to body mass index (BMI) cross-sectionally and longitudinally in school-aged children. SUBJECTS/METHODS All measures were obtained at baseline, 12 and 24 months in 823 children (51% female, 53% European, 18% Māori, 12% Pacific, 9% Asian) aged 6-10 years at baseline. Sleep duration, timing, and quality were measured using actigraphy over 7 days, height and weight were measured using standard techniques, and parents completed questionnaires on demographics (baseline only), dietary intake, and television usage. Data were analysed using imputation; mixed models, with random effects for person and age, estimated both a cross-sectional effect and a longitudinal effect on BMI z-score, adjusted for multiple confounders. RESULTS The estimate of the effect on BMI z-score for each additional hour of sleep was -0.22 (95% CI: -0.33, -0.11) in cross-sectional analyses and -0.05 (-0.10, -0.004) in longitudinal analyses. A greater effect was observed for weekday sleep duration than weekend sleep duration but variability in duration was not related to BMI z-score. While sleep timing (onset or midpoint of sleep) was not related to BMI, children who were awake in the night more frequently (0.19; 0.06, 0.32) or for longer periods (0.18; 0.06, 0.36) had significantly higher BMI z-scores cross-sectionally, but only the estimates for total time awake (minutes) were significant longitudinally (increase in BMI z-score of 0.04 for each additional hour awake). CONCLUSION The beneficial effect of a longer sleep duration on BMI was consistent in children, whereas evidence for markers of sleep quality and timing were more variable.

中文翻译：

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与儿童体重指数相关的客观测量睡眠的数量与质量：横断面和纵向分析。

背景/目标 虽然睡眠时间是儿童肥胖的危险因素，但睡眠质量与体型之间的关系尚不确定。本研究的目的是确定客观测量的睡眠持续时间、睡眠时间和睡眠质量与学龄儿童横断面和纵向的体重指数 (BMI) 之间的关系。对象/方法 在基线、12 个月和 24 个月时，在基线时 6-10 岁的 823 名儿童（51% 女性、53% 欧洲、18% 毛利、12% 太平洋、9% 亚洲）中获得所有测量值。睡眠持续时间、时间和质量使用 7 天的活动记录仪测量，身高和体重使用标准技术测量，父母完成了关于人口统计学（仅基线）、饮食摄入和电视使用情况的问卷调查。使用插补法分析数据；混合模型，通过对人和年龄的随机效应，估计了对 BMI z 分数的横截面效应和纵向效应，并针对多个混杂因素进行了调整。结果 在横断面分析中，每增加一小时睡眠对 BMI z 评分的影响估计值为 -0.22（95% CI：-0.33，-0.11），在纵向分析中为 -0.05（-0.10，-0.004）。观察到工作日睡眠持续时间比周末睡眠持续时间的影响更大，但持续时间的可变性与 BMI z 分数无关。虽然睡眠时间（睡眠开始或中点）与 BMI 无关，但夜间更频繁（0.19；0.06，0.32）或更长时间（0.18；0.06，0.36）醒来的儿童的 BMI z 分数显着更高横断面，但只有总清醒时间（分钟）的估计值在纵向上是显着的（BMI z 分数增加为 0。04 每清醒一小时）。结论 较长睡眠时间对 BMI 的有益影响在儿童中是一致的，而睡眠质量和时间标记的证据则更加可变。