Department of Psychology, University of Warwick, Coventry, UK.
Faculty of Brain Sciences, University College London, London, UK.
J Biol Rhythms. 2021 Apr;36(2):169-184. doi: 10.1177/0748730420974842. Epub 2020 Dec 22.
People differ in their sleep timings that are often referred to as a chronotype and can be operationalized as mid-sleep (midpoint between sleep onset and wake-up). The aims of the present studies were to examine intraindividual variability and longer-term temporal stability of mid-sleep on free and workdays, while also considering the effect of age. We used data from a 2-week experience sampling study of British university students (Study 1) and from a panel study of Estonian adults who filled in the Munich Chronotype Questionnaire twice up to 5 years apart (Study 2). Results of Study 1 showed that roughly 50% of the variance in daily mid-sleep scores across the 14-day period was attributed to intraindividual variability as indicated by the intraclass correlation coefficient. However, when the effect of free versus workdays was considered, the intraindividual variability in daily mid-sleep across 2 weeks was 0.71 the size of the interindividual variability. In Study 2, mid-sleep on free and workdays showed good levels of temporal stability-the retest correlations of mid-sleep on free and workdays were 0.66 and 0.58 when measured twice over a period of 0-1 to 5 years. The retest stability of mid-sleep scores on both free and workdays sharply increased from young adulthood and reached their peak when participants were in late 40 to early 50 years of age, indicating that age influences the stability of mid-sleep. Future long-term longitudinal studies are necessary to explore how age-related life circumstances and other possible factors may influence the intraindividual variability and temporal stability of mid-sleep.
人们的睡眠时间不同，通常被称为睡眠类型，可以用睡眠中点（入睡和醒来之间的中点）来操作化。本研究的目的是检查自由日和工作日的睡眠中点的个体内变异性和长期时间稳定性，同时考虑年龄的影响。我们使用了英国大学生为期两周的体验采样研究的数据（研究 1）和爱沙尼亚成年人的面板研究的数据，这些成年人在长达 5 年的时间里两次填写了慕尼黑睡眠类型问卷（研究 2）。研究 1 的结果表明，在 14 天的时间里，日常睡眠中点得分的大约 50%的方差归因于个体内变异性，这是由组内相关系数表示的。然而，当考虑自由日与工作日的影响时，2 周内日常睡眠中点的个体内变异性是个体间变异性的 0.71 倍。在研究 2 中，自由日和工作日的睡眠中点显示出良好的时间稳定性-自由日和工作日睡眠中点的重测相关系数分别为 0.66 和 0.58，当在 0-1 至 5 年的时间内测量两次时。自由日和工作日睡眠中点得分的重测稳定性从青年期急剧增加，并在参与者年龄在 40 岁到 50 岁出头时达到峰值，这表明年龄影响睡眠中点的稳定性。未来的长期纵向研究是必要的，以探讨与年龄相关的生活环境和其他可能的因素如何影响睡眠中点的个体内变异性和时间稳定性。
