Inter- and intra-variability of sleep patterns in infancy and early childhood

睡眠是儿童时期大脑活动的主要来源之一，在神经发育中起着至关重要的作用。在儿童和成人中，较短的夜间睡眠时间与较差的认知表现有关。然而，这种关系仍处于初级阶段。此外，我们和其他人的工作已经显示了婴儿睡眠模式的主要内部变异性和内部变异性。这种可变性只研究了特定的睡眠变量或主观变量，或在几个晚上。因此，需要做更多的工作来了解婴儿期睡眠变量的可变性，以及它在整个发育过程中的演变。该研究项目的长期目标是推进从婴儿期到青春期整个发育过程中睡眠-觉醒周期变化的知识，以及睡眠变化与认知发展之间的相互作用。本研究的短期目标是：目的1：利用客观的睡眠测量（活动描记术）和几个睡眠变量（持续时间、碎片化），在连续两周的夜晚，对同一个体的睡眠模式变化进行表征。假设1.1不同个体之间存在高度的互变性。在相同的参与者中，睡眠变量也会表现出很高的可变性。假设1.2与碎片化相关的变量将比与持续时间相关的变量显示出更高的内部和内部变异性。目的2：评估睡眠变异性是否在整个发育过程中保持稳定（使用多个时间点的纵向设计- 3,6,12,24,36个月）。假设2.1在所有时间点都可以观察到变异性，但它会随着时间的推移而减少。假设2.2特定婴儿的等级会随着时间的推移保持稳定。目的3：研究哪些睡眠变量在不同发育阶段（同时和纵向）具体预测认知功能。假设3.1 6个月时的睡眠巩固不能预测6个月或36个月时的认知功能。假设3.2 36月龄时的睡眠时间可以预测36月龄时的认知功能。假设3.3考虑到关于该主题的研究较少，将对睡眠模式变异性与认知功能之间的关系进行探索性分析（6,36个月）。考虑到生命最初几年睡眠和认知功能的主要和加速发展，这个研究项目将推进我们对这些动态过程及其相互作用的机制理解。我已经准备好在我的实验室和我的HQP团队一起进行这个拟议的项目。研究结果有望在描述和理解婴儿睡眠模式变化的重要性方面显著推进睡眠和发育神经科学领域。该项目还将在不同的培训阶段为学生提供独特的培训机会。

Sleep is one of the major sources of brain activity in childhood and plays a crucial role in neurodevelopment. In children and adults, shorter nocturnal sleep duration is associated with poorer cognitive performance. However, this relationship remains to clarify in infancy. Moreover, our work and others have shown major inter-variability and intra-variability in infant sleep patterns. This variability was only studied for specific sleep variables or with subjective variables, or during a few nights. Therefore, more work is needed to understand the variability of sleep variables in infancy, as well as its evolution across development. The long-term goal of this research program is to advance knowledge on the sleep-wake cycle variability across development, from infancy to adolescence, as well as the interplay between sleep variability and cognitive development. The short-term goals of this present proposal are to: AIM 1: To characterize sleep patterns variability within the same individuals during a two-week period of consecutive nights, using objective sleep measurements (actigraphy) and several sleep variables (duration, fragmentation). Hypothesis 1.1 High inter-variability will be observed between the different individuals. Within the same participants, sleep variables will also show high variability. Hypothesis 1.2 Variables linked to fragmentation will show higher inter- and intra-variability than variables linked to duration. AIM 2: To evaluate if sleep variability remains stable throughout development (using a longitudinal design with multiple timepoints - 3, 6, 12, 24, 36 months). Hypothesis 2.1 Variability will be observed at all timepoints, but it will decrease over time. Hypothesis 2.2 The rank of a specific infant will remain stable over time. AIM 3: To investigate which sleep variables are specifically predicting cognitive function at different stages of development (both concurrently and longitudinally). Hypothesis 3.1 Sleep consolidation at 6 months will not predict cognitive function at 6 months nor at 36 months. Hypothesis 3.2 Sleep duration at 36 months will predict cognitive function at 36 months old. Hypothesis 3.3 Considering the small number of studies on that topic, an exploratory analysis of the association between sleep patterns variability and cognitive function will be conducted (6, 36 months). Considering the major and accelerated development of sleep and cognitive functions in the first years of life, this program of research will advance our mechanistic understanding of these dynamic processes and their interaction. I am well prepared to undertake this proposed program in my laboratory, with my team of HQP. The results are expected to significantly advance the fields of sleep and developmental neuroscience in describing and understanding the importance of sleep patterns variability in infancy. The program will also offer to students a unique training opportunity, at different stages of training.