Effects of Sleep on Bone Density and Strength in Adolescence: A Prospective Longitudinal Study

摘要/摘要 在成年人中，睡眠受损与骨密度降低和骨折风险增加有关。然而，它是 尚不清楚睡眠模式是否会影响儿童时期骨骼密度和力量的增长。这种知识鸿沟 需要解决的问题是，儿童时期的骨量增加决定了峰值骨量和骨质疏松症的风险 晚年的骨质疏松。长期目标是确定睡眠模式是否能预测骨密度和强度。 在寿命的骨骼生长年限中。这个应用程序的总体目标是确定睡眠是否 模式预测从青春期早期到中期骨密度和强度的变化。12-13岁的青少年 (7年级)将被录取，并预期每年跟踪调查2年。这个年龄段的人 调查是因为这是获得很大比例峰值骨量和强度的关键时期， 当睡眠时间趋于缩短时。在每个时间点，将使用双能量测量骨密度 X射线骨密度仪和骨强度将由高分辨率外周定量计算机测量 体层摄影术。睡眠模式将通过活动记录和自我报告来衡量。DNA将被收集并进行基因分型 因为骨密度和强度是复杂的特征，而对骨脆性的遗传易感性可能会改变 睡眠模式和骨骼结果之间的关联。中心假设是睡眠时间受损， 时机和质量将与青春期骨骼密度和强度的较小增长相关， 对于那些遗传倾向于骨骼脆弱的人来说，相关性更强。这一假设将通过以下方式检验 追求三个具体目标：1)确定睡眠模式是否可以预测青春期骨密度的变化；2) 阐明青春期骨骼强度的变化是否受睡眠模式的影响；以及3)调查 骨脆性遗传评分和睡眠模式对青春期骨骼变化的综合影响。这个 申请者在青少年中的初步数据显示，睡眠时间与睡眠时间之间呈倒U形关系 和面积骨密度，他们观察到较晚的睡眠开始时间预示着较低的面积骨 矿物质密度和较低的骨强度。研究人员还证明，骨骼脆性遗传分数 与儿童和青少年较低的面骨密度有关，但与生活方式因素(在这种情况下)有关 体力活动)可以帮助克服遗传上的负面影响。建议进行这项研究的理由是 需要建立一个严格的流行病学证据基础来支持睡眠和睡眠之间的联系 骨骼结果，这将为进行针对睡眠模式和 评估骨聚集性。这种方法是创新的，因为睡眠模式还没有被认为是 青春期骨量和强度的预测指标，以及先进的成像方法将与 先进的生长、睡眠和遗传流行病学方法。关于结果，调查人员 预计他们将建立睡眠模式，作为青春期骨密度和强度的关键预测因素。

SUMMARY/ABSTRACT Impaired sleep has been linked with lower bone density and increased risk of fracture in adults. However, it is not known if sleep patterns effect gains in bone density and strength during childhood. This knowledge gap needs to be addressed because bone accretion in childhood determines peak bone mass and risk of osteoporosis in later life. The long-term goal is to determine if sleep patterns predict bone density and strength during the bone accretion years of the lifespan. The overall objective of this application is to determine if sleep patterns predict changes in bone density and strength from early-to-mid adolescence. Adolescents aged 12-13y (7th grade) will be enrolled and prospectively followed-up annually for 2-years. This age range is being investigated because this is a critical period when a large proportion of peak bone mass and strength are gained, and when sleep duration tends to decline. At each time point, bone density will be measured using dual energy X-ray absorptiometry and bone strength will be measured by high resolution peripheral quantitative computed tomography. Sleep patterns will be measured by actigraphy and self-report. DNA will be collected and genotyped because bone density and strength are complex traits and genetic susceptibility to bone fragility may modify the association between sleep patterns and bone outcomes. The central hypothesis is that impaired sleep duration, timing and quality will be associated with lesser gains in bone density and strength in adolescence, with the associations stronger for those genetically predisposed to bone fragility. This hypothesis will be tested by pursuing three specific aims: 1) Determine if sleep patterns predict changes in bone density in adolescence; 2) Elucidate if bone strength changes during adolescence are influenced by sleep patterns; and 3) Investigate the combined effect of bone fragility genetic scores and sleep patterns on bone changes during adolescence. The applicants’ preliminary data among adolescents show an inverted U-shaped association between sleep duration and areal bone mineral density, and they observed that later timing of sleep onset predicted lower areal bone mineral density and lower bone strength. The investigators also demonstrated that bone fragility genetic scores associated with lower areal bone mineral density in children and adolescents, but a lifestyle factor (in this case physical activity) could help overcome the negative genetic effects. The rationale for the proposed research is the need to establish a rigorous base of epidemiological evidence supporting associations between sleep and bone outcomes, which will provide a foundation to perform intervention studies that target sleep patterns and evaluate bone accretion. The approach is innovative because sleep patterns have not yet been considered as predictors of bone mass and strength in adolescence, and advanced imaging methods will be combined with advanced growth, sleep and genetic epidemiological methods. With respect to outcomes, the investigators anticipate that they will establish sleep patterns as key predictors of bone density and strength in adolescence.