ABSTRACT

Sleep and the sleep-wake rhythm are essential for children’s health and well-being, yet reference values are lacking. This study therefore aimed to assess actigraphic estimates of sleep and the 24-h sleep-wake rhythm, as well as 6-sulfatoxymelatonin (aMT6s) levels in healthy children of different age groups. Additionally, relationships between the outcomes and sex, highest parental educational level (as an indication of socioeconomic status (SES)), and body-mass-index (BMI) were explored. In this cross-sectional study, healthy Dutch children (2–18 years) wore an actigraph (GT3x) for 7 consecutive days, collected first-morning void urine and completed a sleep log and sociodemographic questionnaire. Actigraphically estimated sleep variables were sleep onset latency (SOL), sleep efficiency (SE), total sleep time (TST), and wake after sleep onset (WASO). Non-parametric sleep-wake rhythm variables were intradaily variability (IV); interdaily stability (IS); the activity counts and timing of the least active 5-h period (L5counts and midpoint) and of the most active 10-h period (M10 counts and midpoint); and the relative amplitude (RA), i.e. the ratio of the difference and the sum of M10 and L5 counts. Finally, creatinine-corrected aMT6s levels were obtained by isotope dilution mass spectrometry. Effects of age group (preschool 2–5 years/school-aged 6–12 years/teenager 13–18 years), sex, highest parental educational level and BMI (Z-scores) were explored. Ninety-four children participated, equally divided across age groups (53% boys). Teenagers slept less, but more efficiently, than younger children, while their 24 h sleep-wake rhythm was the least stable and most fragmented (likely due to fragmentation of daytime activity). Additionally, aMT6s levels significantly declined over the age groups. Children from highly educated parents had lower sleep efficiency, but a more stable sleep-wake rhythm. Finally, sex or increase in BMI was not associated with any of the outcomes in this study. In conclusion, this study provides reference values of healthy children across different age groups and different sociodemographic factors. In the future, this information may help to better interpret outcomes in clinical populations.

摘要

睡眠和觉醒节律对儿童的健康和福祉至关重要，但缺乏参考价值。因此，本研究旨在评估不同年龄组健康儿童的睡眠，24小时睡眠-觉醒节律以及6-巯基氧基褪黑激素（aMT6s）水平的活动估计。此外，还探讨了结局与性别，最高的父母教育水平（作为社会经济地位（SES）的指标）和身体质量指数（BMI）之间的关系。在这项横断面研究中，健康的荷兰儿童（2至18岁）连续7天戴着电子记录仪（GT3x），收集了第一时间清晨的尿液，并完成了睡眠记录和社会人口统计学问卷。依书法估算的睡眠变量包括睡眠发作潜伏期（SOL），睡眠效率（SE），总睡眠时间（TST），并在入睡后醒来（WASO）。非参数睡眠-觉醒节律变量为日内变异性（IV）；日间稳定性（IS）；最不活跃的5小时周期（L5计数和中点）和最活跃的10小时周期（M10计数和中点）的活动计数和计时；相对振幅（RA），即差异与M10和L5计数之和的比率。最后，通过同位素稀释质谱法获得肌酐校正的aMT6s水平。研究了年龄组（学龄前2-5岁/学龄6-12岁/青少年13-18岁），性别，最高父母教育水平和BMI（Z评分）的影响。共有94名儿童参加，平均分为各个年龄段（男孩为53％）。与年幼的孩子相比，青少年的睡眠更少，但效率更高，而他们的24小时睡眠/苏醒节律则最不稳定且最不完整（可能是由于白天活动的不完整所致）。此外，随着年龄的增长，aMT6s水平也明显下降。受过良好教育的父母的孩子的睡眠效率较低，但睡眠-觉醒节奏更稳定。最后，性别或BMI升高与本研究的任何结局均无关。总之，这项研究为不同年龄段和不同社会人口统计学因素的健康儿童提供了参考价值。将来，这些信息可能有助于更好地解释临床人群的预后。但更稳定的觉醒节奏。最后，性别或BMI升高与本研究的任何结局均无关。总之，这项研究为不同年龄段和不同社会人口统计学因素的健康儿童提供了参考价值。将来，这些信息可能有助于更好地解释临床人群的预后。但更稳定的觉醒节奏。最后，性别或BMI升高与本研究的任何结局均无关。总之，这项研究为不同年龄段和不同社会人口统计学因素的健康儿童提供了参考价值。将来，这些信息可能有助于更好地解释临床人群的预后。