Data_Sheet_1_Is Metabolic Rate Increased in Insomnia Disorder? A Systematic Review.docx

Background: Insomnia disorder is a highly prevalent health condition, affecting ~10–15% of the adult population worldwide. A central feature of insomnia is hyperarousal characterized as persistent and increased somatic, cognitive and cortical stimulation. Hyperarousal leads to a state of conditioned arousal that disrupts both sleep and daytime function. Research studies have shown increases in body temperature, heart rate, electroencephalographic activity, catecholamines, and oxygen consumption as a measure of metabolic rate. These findings provide evidence of increased physiological activation in insomnia however results are not consistent. The aim of the systematic review was to determine if metabolic rate in patients with insomnia is increased in keeping with the hyperarousal hypothesis.
Methods: We searched Pubmed, Web of Science, CINAHL, PsycINFO, EMBASE, and Scopus databases for observational and interventional studies that have measured metabolic rate in insomnia. Study characteristics were extracted and summarized and a risk of bias was performed for each of the studies.
Results: Two reviewers screened 963 abstracts with 35 articles of interest for full-text review. Four articles evaluating 75 participants were included in this systematic review. Two studies showed increased oxygen consumption across 24 h in insomnia patients compared with good-sleeping controls. One study which measured oxygen consumption at only a single timepoint showed no difference between insomnia patients and good-sleeping controls. A further study evaluating the effect of lorazepam on oxygen consumption in patients with chronic insomnia showed that lorazepam reduced metabolic rate during the night time only.
Conclusions: These findings show that metabolic rate appears to be increased across 24 h in line with the hyperarousal model of insomnia. However, these increases in metabolic rate in insomnia were minor compared to good-sleeping controls and the clinical significance is unclear. Larger, methodologically robust studies are required to confirm these findings and the effect of any increase in metabolic rate on sleep-wake disturbances or pathophysiology.

背景：失眠障碍（Insomnia disorder）是一种高发性健康问题，全球约有10%~15%的成年人群受其影响。失眠症的核心特征为高唤醒（hyperarousal），表现为躯体、认知及皮层刺激持续增强。高唤醒会引发条件性唤醒状态，进而干扰睡眠与日间功能。已有研究显示，体温、心率、脑电图（electroencephalographic）活动、儿茶酚胺（catecholamines）水平以及作为代谢率（metabolic rate）衡量指标的耗氧量均有所升高。上述发现为失眠症患者存在生理激活增强提供了佐证，但相关研究结果并不一致。本系统综述的目的在于验证失眠症患者的代谢率是否符合高唤醒假说，即是否存在升高情况。

方法：我们检索了PubMed、Web of Science、CINAHL、PsycINFO、EMBASE及Scopus数据库，筛选出所有针对失眠症患者代谢率进行测量的观察性与干预性研究。研究人员提取并汇总了各项研究的特征信息，并对每项研究进行了偏倚风险评估。

结果：两名研究人员共筛选了963篇摘要，其中35篇符合要求并进入全文审阅环节。最终本系统综述纳入了4项研究，共涉及75名受试者。其中两项研究显示，与睡眠良好的对照组相比，失眠症患者的24小时整体耗氧量更高。另有一项仅在单个时间点测量耗氧量的研究显示，失眠症患者与睡眠良好对照组的耗氧量并无差异。还有一项评估劳拉西泮（lorazepam）对慢性失眠症患者耗氧量影响的研究显示，劳拉西泮仅能在夜间降低患者的代谢率。

结论：本研究结果显示，失眠症患者的24小时代谢率整体升高，这与失眠症的高唤醒模型相符。但与睡眠良好对照组相比，失眠症患者的代谢率升高幅度较小，且其临床意义尚不明确。未来需开展样本量更大、方法学更严谨的研究，以验证本研究结论，并明确代谢率升高对睡眠-觉醒紊乱或病理生理学的影响。