Combined association of clinical and lifestyle factors with non-restorative sleep: The Nagahama Study

Background
Non-restorative sleep (NRS) was suggested to be associated with cardiovascular outcomes. However, causative factors for NRS have not been fully elucidated. This study aimed to clarify factors and their relationships with NRS to better understand the clinical and epidemiological implications of NRS and to develop a score that can objectively evaluate NRS status.
Methods
Study subjects consisted of 9,788 community residents (age 53.6 ± 13.4 y). Subjective NRS as well as possible clinical and lifestyle factors for NRS were investigated by questionnaires. Other clinical parameters were obtained from personal records of information obtained at the baseline examination.
Results
A total of 3,261 participants complained of NRS. Factors independently associated with subjective NRS were younger age (odds ratio = 1.43), use of a hypnotic drug (2.04), irregular sleep schedule (2.02), short sleep duration (<5 h, 11.7; 5–6 h, 4.81; 6–7 h, 2.40), frequent sleepiness (2.33), routine stress (4.63), no habitual exercise (1.61), nocturia symptoms (1.43), symptoms of gastroesophageal reflux disease (1.44), and depression (1.46) (all P <0.001). The NRS score comprised of these 10 factors was linearly associated with the frequency of subjective NRS (Ptrend <0.001). Frequency of individuals with a high NRS score was greater in women (52.3%) than in men (42.1%, P<0.001), while no clear association was observed with common risk factors for cardiovascular diseases.
Conclusions
NRS was a phenomenon representing various clinical and lifestyle features. Careful attention should be paid to individuals with a high NRS score who might be at risk for mental fatigue and have unfavorable lifestyle factors.

研究背景
有研究提示非恢复性睡眠（Non-restorative sleep, NRS）与心血管不良结局存在关联。然而，目前尚未完全阐明非恢复性睡眠的致病因素。本研究旨在明确与非恢复性睡眠相关的各类因素及其相互关系，以更好地理解非恢复性睡眠的临床与流行病学意义，并开发一种可客观评估非恢复性睡眠状态的评分体系。

研究方法
本研究的研究对象为9788名社区居民，年龄为53.6±13.4岁。研究通过问卷调查的方式，收集了受试者的主观非恢复性睡眠情况，以及可能与非恢复性睡眠相关的临床与生活方式因素。其余临床参数则来源于基线检查时获取的个人健康记录。

研究结果
共计3261名受试者自述存在非恢复性睡眠情况。与主观非恢复性睡眠独立相关的因素包括：年龄较轻（优势比=1.43）、使用催眠药物（2.04）、睡眠节律不规律（2.02）、睡眠时长过短（<5小时：11.7；5~6小时：4.81；6~7小时：2.40）、日间嗜睡频发（2.33）、日常应激水平较高（4.63）、无规律运动习惯（1.61）、存在夜尿症症状（1.43）、存在胃食管反流病症状（1.44）以及抑郁状态（1.46）（所有P值均<0.001）。基于上述10项因素构建的非恢复性睡眠评分，与主观非恢复性睡眠的发生频率呈线性相关（趋势检验P<0.001）。非恢复性睡眠评分较高的人群中，女性占比（52.3%）高于男性（42.1%，P<0.001）；而该评分与常见心血管疾病危险因素未观察到明确关联。

研究结论
非恢复性睡眠是一种反映多种临床与生活方式特征的现象。对于非恢复性睡眠评分较高的人群，应予以密切关注，此类个体可能存在精神疲劳风险，且伴随不良生活方式因素。