Morgan Ethan, Schumm L Philip, McClintock Martha, Waite Linda, Lauderdale Diane S
Department of Public Health Sciences, University of Chicago, Chicago, IL.
Department of Psychology, University of Chicago, Chicago, IL.
Sleep. 2017 May 1;40(5). doi: 10.1093/sleep/zsx043.
Older adults frequently report sleep problems and are at increased risk of cardiometabolic disruption. Experimental sleep restriction of younger adults has suggested that cortisol may be on the pathway between sleep restriction and cardiometabolic disease. We investigated whether the natural variation in sleep among older adults is associated with daytime cortisol level.
Salivary cortisol samples and actigraphy sleep data were collected from a random subsample of participants in the National Social Life, Health and Aging Project, a nationally representative probability sample of adults aged 62-90 (N = 672). Salivary cortisol was measured with 3 timed samples at the beginning, middle, and end of a 2-hr in-home interview. Sleep characteristics were derived from wrist actigraphy (fragmentation, wake after sleep onset [WASO], and duration) and from survey responses about usual sleep duration and sleep problems. For each individual, a single summary daytime cortisol level was estimated by fitting a marginal longitudinal model for the 3 time-stamped cortisol samples. The resulting estimates were then regressed on each sleep measure, adjusting for sociodemographics, health behaviors, and comorbidities.
From actigraphy, both higher fragmentation score (β = 0.02; 95% confidence interval [CI] = 0.00 to 0.03) and longer WASO (β = 0.27; 95% CI = 0.04 to 0.51) were significantly associated with higher daytime cortisol; sleep duration was not. Self-reported sleep duration and sleep problems were also not associated with cortisol.
Actigraph measures of sleep disturbance are associated with higher daytime cortisol among older adults. However, cross-sectional data cannot distinguish causal direction or whether cortisol and sleep disruption have a common cause.
老年人经常报告存在睡眠问题，且发生心脏代谢紊乱的风险增加。对年轻人进行的实验性睡眠限制表明，皮质醇可能处于睡眠限制与心脏代谢疾病之间的关联路径上。我们调查了老年人睡眠的自然变化是否与日间皮质醇水平相关。
从“全国社会生活、健康与老龄化项目”的参与者随机子样本中收集唾液皮质醇样本和活动记录仪睡眠数据，该项目是一个具有全国代表性的62 - 90岁成年人概率样本（N = 672）。在为期2小时的家庭访谈开始、中间和结束时，通过3次定时采样测量唾液皮质醇。睡眠特征来自手腕活动记录仪（睡眠碎片化、睡眠后觉醒时间[WASO]和睡眠时间）以及关于通常睡眠时间和睡眠问题的调查回复。对于每个个体，通过对3个有时间标记的皮质醇样本拟合边际纵向模型来估计单个日间皮质醇水平汇总值。然后将所得估计值对每个睡眠指标进行回归分析，并对社会人口统计学、健康行为和合并症进行调整。
从活动记录仪数据来看，较高的睡眠碎片化得分（β = 0.02；95%置信区间[CI] = 0.00至0.03）和较长的WASO（β = 0.27；95% CI = 0.04至0.51）均与较高的日间皮质醇显著相关；睡眠时间则不然。自我报告的睡眠时间和睡眠问题也与皮质醇无关。
活动记录仪测量的睡眠障碍与老年人较高的日间皮质醇相关。然而，横断面数据无法区分因果方向，也无法确定皮质醇和睡眠障碍是否有共同原因。
