Monk Timothy H, Thompson Wesley K, Buysse Daniel J, Hall Martica, Nofzinger Eric A, Reynolds Charles F
Clinical Neuroscience Research Center, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, PA 15213, USA.
J Sleep Res. 2006 Sep;15(3):256-60. doi: 10.1111/j.1365-2869.2006.00534.x.
The aim of this study was to determine whether naturally occurring inter-individual and intra-individual differences in bedtime selection in the elderly might be lawfully related to the amount of sleep that is obtained. A total of 128 seniors (63f, 65m) aged 70-92 years each provided a week of sleep diary data yielding a total of 896 subject-nights for analysis. From each subject-night the diary was used to derive measures of time in bed (TIB) and total sleep time (TST). These measures were used as dependent variables in mixed-effect linear models (nights nested within subjects) with the independent variable being bedtime for that subject-night, arbitrarily expressed as minutes since 19:00 hours. Although there were strong inter-individual and intra-individual differences, for both genders, bedtime had a statistically significant effect (P < 0.001) on both TIB and TST. We observed that later bedtimes were associated with less time in bed and less time asleep. On average between 7 and 8 min of less TIB and TST were associated with each 10-min delay in bedtime from 19:00 hours. These results are interpreted in terms of increases in sleep being derived from living in a better harmony with an earlier peaking circadian pacemaker characteristic of older age, although other possible mechanisms are also considered (e.g. age-dependent alterations in phase angle and homeostatic sleep need).
本研究的目的是确定老年人自然存在的个体间和个体内就寝时间选择差异是否与所获得的睡眠量存在规律关联。共有128名70 - 92岁的老年人（63名女性，65名男性）每人提供了一周的睡眠日记数据，共计896个受试者夜晚的数据用于分析。从每个受试者夜晚的日记中得出卧床时间（TIB）和总睡眠时间（TST）的测量值。这些测量值在混合效应线性模型（受试者内嵌套夜晚）中用作因变量，自变量是该受试者夜晚的就寝时间，以自19:00起的分钟数表示。尽管存在很强的个体间和个体内差异，但对于两性而言，就寝时间对TIB和TST均有统计学显著影响（P < 0.001）。我们观察到较晚的就寝时间与较短的卧床时间和睡眠时间相关。就寝时间从19:00起每延迟10分钟，平均TIB和TST会减少7至8分钟。这些结果可以解释为，睡眠增加源于与老年人更早达到峰值的昼夜节律起搏器更好地协调，不过也考虑了其他可能的机制（例如相位角的年龄依赖性改变和内稳态睡眠需求）。
