Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland.
Pediatric Research Center, Child Psychiatry, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
J Sleep Res. 2020 Jun;29(3):e12918. doi: 10.1111/jsr.12918. Epub 2019 Sep 8.
Circadian rhythms refer to biological rhythms that have an endogenous period length of approximately 24 hr. However, not much is known about the variance in the development of the sleep-wake rhythm. The study objectives were (a) to describe the normative variation in the development of a sleep-wake rhythm in infancy, (b) to assess whether slower development is related to sleep quality and (c) to evaluate factors that are related to the slower development of a sleep-wake rhythm. The study is based on a representative birth cohort. Questionnaires at the ages of 3 (n = 1,427) and 8 months (n = 1,302) and actigraph measurement at 8 months (n = 372) were available. Infants with significant developmental delays (n = 11) were excluded. The results are based on statistical testing and multivariate modelling. We found that the average percentage of daytime sleep was 36.3% (standard deviation [SD], 8.5%) at 3 months and 25.6% (SD, 6.6%) at 8 months. At both time-points, infants with slower sleep-wake rhythm development slept more hours per day, had a later sleep-wake rhythm, more difficulties in settling to sleep and longer sleep-onset latency; they also spent a longer time awake during the night. According to actigraph registrations, we found that the infants with slow development of a sleep-wake rhythm slept less and had a later start and end to night-time sleep than the other infants. Infants' sleep-wake rhythm development is highly variable and is related to parent-reported and objectively measured sleep quality and quantity. Interventions to improve the sleep-wake rhythm might improve sleep quality in these infants.
昼夜节律是指具有大约 24 小时内源性周期长度的生物节律。然而，对于睡眠-觉醒节律的发展变化，我们知之甚少。本研究的目的是：(a)描述婴儿期睡眠-觉醒节律发展的正常变化；(b)评估发育较慢是否与睡眠质量有关；(c)评估与睡眠-觉醒节律发育较慢相关的因素。本研究基于一个具有代表性的出生队列。在 3 个月龄（n=1427）和 8 个月龄（n=1302）时使用问卷，在 8 个月龄（n=372）时使用活动记录仪进行测量。排除有明显发育迟缓的婴儿（n=11）。结果基于统计检验和多变量建模。我们发现，3 个月龄时白天睡眠时间的平均百分比为 36.3%（标准差[SD]，8.5%），8 个月龄时为 25.6%（SD，6.6%）。在这两个时间点，睡眠-觉醒节律发育较慢的婴儿每天睡眠时间更长，睡眠-觉醒节律较晚，入睡困难，入睡潜伏期较长；他们在夜间也会更长时间保持清醒。根据活动记录仪的记录，我们发现，睡眠-觉醒节律发育较慢的婴儿夜间睡眠时间较少，入睡和结束时间较晚。婴儿睡眠-觉醒节律的发展变化很大，与父母报告和客观测量的睡眠质量和数量有关。改善睡眠-觉醒节律的干预措施可能会改善这些婴儿的睡眠质量。
