Urbanek Jacek K, Spira Adam P, Di Junrui, Leroux Andrew, Crainiceanu Ciprian, Zipunnikov Vadim
a Department of Medicine , Johns Hopkins University School of Medicine , Baltimore , Maryland , US.
b Department of Mental Health , Johns Hopkins Bloomberg School of Public Health , Baltimore , Maryland , US.
Chronobiol Int. 2018 Mar;35(3):416-434. doi: 10.1080/07420528.2017.1411359. Epub 2017 Dec 28.
We propose a method for estimating the timing of in-bed intervals using objective data in a large representative US sample, and quantify the association between these intervals and age, sex, and day of the week.
The study included 11,951 participants 6 years and older from the National Health and Nutrition Examination Survey (NHANES) 2003-2006, who wore accelerometers to measure physical activity for seven consecutive days. Participants were instructed to remove the device just before the nighttime sleep period and put it back on immediately after. This nighttime period of non-wear was defined in this paper as the objective bedtime (OBT), an objectively estimated record of the in-bed interval. For each night of the week, we estimated two measures: the duration of the OBT (OBT-D) and, as a measure of the chronotype, the midpoint of the OBT (OBT-M). We estimated day-of-the-week-specific OBT-D and OBT-M using gender-specific population percentile curves. Differences in OBT-M (chronotype) and OBT-D (the amount of time spent in bed) by age and sex were estimated using regression models.
The estimates of OBT-M and their differences among age groups were consistent with the estimates of chronotype obtained via self-report in European populations. The average OBT-M varied significantly by age, while OBT-D was less variable with age. In the reference group (females, aged 17-22 years), the average OBT-M across 7 days was 4:19 AM (SD = 30 min) and the average OBT-D was 9 h 19 min (SD = 12 min). In the same age group the average OBT-D was 18 minutes shorter for males than for females, while the average OBT-M was not significantly different between males and females. The most pronounced differences were observed between OBT-M of weekday and weekend nights. In the reference group, compared to the average OBT-M of 3:50 am on Monday through Thursday nights, there was a 57-minute delay in OBT-M on Friday nights (entering the weekend), a 69-minute delay on Saturday nights (staying in the weekend), and a 23-minute delay on Sunday night (leaving the weekend). For both OBT-M and OBT-D, in most age groups and for most days of the week, there were no statistically significant differences between males and females, except for OBT-D on Wednesdays and Thursdays, with males having 31 (p-value < 0.05) and 45 (p-value < 0.05) minutes shorter OBT-D, respectively.
The proposed measures, OBT-D and OBT-M, provide useful information of time in bed and chronotype in NHANES 2003-2006. They identify within-week patterns of bedtime and can be used to study associations between the bedtime and the large number of health outcomes collected in NHANES 2003-2006.
我们提出了一种利用美国大型代表性样本中的客观数据来估计卧床时间的方法，并量化这些时间段与年龄、性别和星期几之间的关联。
该研究纳入了2003 - 2006年国家健康与营养检查调查（NHANES）中11,951名6岁及以上的参与者，他们连续七天佩戴加速度计来测量身体活动情况。参与者被要求在夜间睡眠时间前取下设备，并在睡眠结束后立即重新佩戴。本文将这段夜间不佩戴设备的时间定义为客观就寝时间（OBT），即对卧床时间的客观估计记录。对于一周中的每个夜晚，我们估计了两个指标：OBT的持续时间（OBT - D），以及作为昼夜节律类型指标的OBT中点（OBT - M）。我们使用特定性别的人群百分位数曲线来估计一周中每天的OBT - D和OBT - M。通过回归模型估计年龄和性别在OBT - M（昼夜节律类型）和OBT - D（卧床时间）方面的差异。
OBT - M的估计值及其在各年龄组之间的差异与欧洲人群通过自我报告获得的昼夜节律类型估计值一致。平均OBT - M随年龄有显著差异，而OBT - D随年龄的变化较小。在参考组（17 - 22岁女性）中，7天的平均OBT - M为凌晨4:19（标准差 = 30分钟），平均OBT - D为9小时19分钟（标准差 = 12分钟）。在同一年龄组中，男性的平均OBT - D比女性短18分钟，而男性和女性的平均OBT - M没有显著差异。在工作日和周末夜晚的OBT - M之间观察到最明显的差异。在参考组中，与周一至周四晚上凌晨3:50的平均OBT - M相比，周五晚上（进入周末）的OBT - M延迟了57分钟，周六晚上（处于周末）延迟了69分钟，周日晚上（离开周末）延迟了23分钟。对于OBT - M和OBT - D，在大多数年龄组和一周中的大多数日子里，男性和女性之间没有统计学上的显著差异，除了周三和周四的OBT - D，男性的OBT - D分别短31分钟（p值 < 0.05）和45分钟（p值 < 0.05）。
所提出的指标OBT - D和OBT - M为2003 - 2006年NHANES中的卧床时间和昼夜节律类型提供了有用信息。它们识别了一周内的就寝时间模式，并可用于研究2003 - 2006年NHANES中收集的就寝时间与大量健康结果之间的关联。
