Rao Madhu N, Blackwell Terri, Redline Susan, Punjabi Naresh M, Barrett-Connor Elizabeth, Neylan Thomas C, Stone Katie L
Division of Endocrinology, University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2013 Sep 27;8(9):e75205. doi: 10.1371/journal.pone.0075205. eCollection 2013.
Short sleep duration is associated with adverse health outcomes, but the mechanisms involved are unknown. It has been postulated that short sleep duration may elevate cortisol levels, but studies have had conflicting results. It is unclear whether these differing findings may be due to methodological issues, such as assessment of sleep duration. Specifically, objective versus subjective methods of measuring habitual sleep duration may account for the conflicting results found in epidemiological studies.
Our goal was to determine whether habitual sleep duration, measured objectively (by actigraphy) and subjectively (by self-report), was associated with 24-hour urine free cortisol (UFC), a measure of integrated cortisol secretion. Our secondary goal was to determine whether slow wave sleep (SWS, determined by polysomnography) was associated with 24-hour UFC.
DESIGN/SETTING: Cross sectional study of community dwelling older men.
PATIENTS/PARTICIPANTS: 325 men (mean age = 76.6 years, SD = 5.5) from the Portland site of the MrOS Sleep Study, who underwent 24-hour urine collection, polysomnography, actigraphy and sleep questionnaire.
24-hour UFC.
In this study of community dwelling older men, self-reported sleep duration was inversely related to 24-hour UFC levels. Participants reporting <5 hours of habitual sleep had an adjusted mean 24-hour UFC of 29.8 ug, compared to 28.0 ug in participants reporting >5 to <8 hours of sleep 25.5 ug in those reporting >8 hours of habitual sleep. However, sleep duration determined by actigraphy was not associated with 24-hour UFC in either univariable or multivariable regression models. SWS was not associated with 24-hour UFC.
Objectively measured (i.e., actigraphic) sleep duration is not associated with 24-hour UFC in these community dwelling older men. This finding, together with prior studies, suggests that elevated levels of integrated cortisol secretion is not the mechanisms by which short sleep duration leads to adverse health outcomes.
睡眠时间短与不良健康后果相关，但其中涉及的机制尚不清楚。据推测，睡眠时间短可能会提高皮质醇水平，但研究结果相互矛盾。目前尚不清楚这些不同的发现是否可能归因于方法学问题，例如睡眠时间的评估。具体而言，测量习惯性睡眠时间的客观方法与主观方法可能是导致流行病学研究结果相互矛盾的原因。
我们的目标是确定通过客观（通过活动记录仪）和主观（通过自我报告）测量的习惯性睡眠时间是否与24小时尿游离皮质醇（UFC）相关，UFC是一种综合皮质醇分泌的指标。我们的次要目标是确定慢波睡眠（SWS，通过多导睡眠图确定）是否与24小时UFC相关。
设计/地点：对社区居住的老年男性进行横断面研究。
患者/参与者：来自MrOS睡眠研究波特兰站点的325名男性（平均年龄 = 76.6岁，标准差 = 5.5），他们接受了24小时尿液收集、多导睡眠图、活动记录仪和睡眠问卷调查。
24小时UFC。
在这项对社区居住老年男性的研究中，自我报告的睡眠时间与24小时UFC水平呈负相关。报告习惯性睡眠时间<5小时的参与者调整后的平均24小时UFC为29.8微克，而报告睡眠时间>5至<8小时的参与者为28.0微克，报告习惯性睡眠时间>8小时的参与者为25.5微克。然而，在单变量或多变量回归模型中，通过活动记录仪确定的睡眠时间与24小时UFC均无关联。SWS与24小时UFC无关。
在这些社区居住的老年男性中，客观测量（即通过活动记录仪）的睡眠时间与24小时UFC无关。这一发现与先前的研究共同表明，综合皮质醇分泌水平升高并非睡眠时间短导致不良健康后果的机制。
