Healthy sleep habits are protective against adverse health outcomes, but it is unclear how strongly sleep intraindividual variability is associated with cognitive function among older adults. In this study we aimed to examine how accelerometer-derived intraindividual variability in sleep duration, efficiency, onset timing, and offset timing is associated with cognition using cross-sectional data from the 2011-2014 waves of the National Health and Nutrition Examination Survey (NHANES). Cognition was assessed by creating a composite measure derived by summing z-scores from the Digit Symbol Substitution Test (DSST), Consortium to Establish a Registry for Alzheimers Disease Word-Learning subtest (CERAD-WL), and the Animal Fluency Test (AFT). A final cohort of 2508 older adults aged 60+ with at least three days of accelerometer wear time who completed all three cognitive tests were included in this study. After centering all sleep intraindividual variability metrics and adjusting for demographic factors, the presence of diabetes, depressive symptoms, and measures of functional independence, we found that increased intraindividual variability in sleep onset timing was associated with worse cognition (Beta, -0.12; 95% CI, -0.19 to -0.05), as was increased intraindividual variability in sleep efficiency (Beta, -0.12; 95% CI, -0.20 to -0.05), and increased interindividual variability in sleep duration (Beta, -0.10; 95% CI, -0.17 to -0.03). This study suggests that sleep guidance aimed at preserving cognition among older adults could be revised to include a focus on sleep consistency regarding onset timing, quality, and duration.

翻译：健康睡眠习惯有助于预防不良健康结局，但尚不明确睡眠个体内变异性与老年人认知功能之间的关联强度。本研究旨在利用2011-2014年国家健康与营养调查（NHANES）的横断面数据，探讨加速度计测量的睡眠时长、睡眠效率、入睡时间及觉醒时间的个体内变异性与认知功能的关联。认知功能通过计算数字符号替代测试（DSST）、阿尔茨海默病登记联盟词语学习子测试（CERAD-WL）和动物流畅性测试（AFT）的z-score总和构建的复合指标进行评估。最终纳入2508名60岁及以上老年人，其加速度计佩戴时间不少于三天，并完成全部三项认知测试。在中心化所有睡眠个体内变异性指标并调整人口学因素、糖尿病患病状况、抑郁症状及功能独立性指标后，本研究发现：入睡时间个体内变异性增加与认知功能下降相关（Beta=-0.12；95% CI，-0.19至-0.05），睡眠效率个体内变异性增加与认知功能下降相关（Beta=-0.12；95% CI，-0.20至-0.05），睡眠时长个体内变异性增加也与认知功能下降相关（Beta=-0.10；95% CI，-0.17至-0.03）。本研究提示，旨在保护老年人认知功能的睡眠指导建议应修订纳入对入睡时间、睡眠质量及时长一致性的关注。