Department of Experimental Clinical and Health Psychology, Ghent University, 9000 Gent, Belgium.
Department of Psychology and Sociology, Area of Psychobiology, University of Zaragoza, 44003 Teruel, Spain.
Int J Environ Res Public Health. 2020 Feb 16;17(4):1264. doi: 10.3390/ijerph17041264.
The aim of this study was to investigate whether the nighttime cortisol release was associated with subjective and objective sleep quality and the discrepancy between them. Forty-five healthy older adults (age range from 56 to 75 years) collected salivary samples immediately before sleep and immediately after awakening on two consecutive nights. Actigraphy was used to assess objective sleep quality and quantity. A sleep diary was used to assess subjective sleep quality. Linear mixed models were performed using subjective and objective sleep quality data from 76 nights to investigate between-subject associations. We observed that larger changes in cortisol levels between sleep onset and awakening, reflecting a healthier circadian rhythm of the Hypothalamic-Pituitary-Adrenal (HPA) axis, were associated with better subjective sleep quality, but not with objective sleep quality. Moreover, smaller changes in nighttime cortisol were associated with lower subjective sleep quality relative to objective sleep quality. All these results were observed even after controlling for important confounders such as sleep quantity, age, sex, subjective socioeconomic status, stress perception, depression, physical activity, and adherence to the salivary sampling protocol. This study demonstrates that subjective sleep quality in older people may be explained, to some extent, by the activity of the HPA axis.
本研究旨在探讨夜间皮质醇释放与主观和客观睡眠质量及其差异之间是否存在关联。45 名健康老年人（年龄 56-75 岁）连续两晚在睡前和醒来后立即采集唾液样本。活动记录仪用于评估客观睡眠质量和数量。睡眠日记用于评估主观睡眠质量。使用 76 个晚上的主观和客观睡眠质量数据，通过线性混合模型进行了个体间关联分析。我们发现，入睡和觉醒之间皮质醇水平变化越大，反映下丘脑-垂体-肾上腺（HPA）轴的昼夜节律越健康，与主观睡眠质量越好相关，但与客观睡眠质量无关。此外，夜间皮质醇变化较小与主观睡眠质量相对于客观睡眠质量较低相关。即使在控制了重要的混杂因素（如睡眠量、年龄、性别、主观社会经济地位、压力感知、抑郁、身体活动和唾液采样方案的依从性）后，这些结果仍然存在。本研究表明，老年人的主观睡眠质量在一定程度上可以通过 HPA 轴的活动来解释。
