Background: Sleep-wakefulness cycles are an essential diagnostic criterion for Disorders of Consciousness (DOC), differentiating prolonged DOC from coma. Specific sleep features, like the presence of sleep spindles, are an important marker for the prognosis of recovery from DOC. Based on increasing evidence for a link between sleep and neuronal plasticity, understanding sleep in DOC might facilitate the development of novel methods for rehabilitation. Yet, well-controlled studies of sleep in DOC are lacking. Here, we aimed to quantify, on a reliable evaluation basis, the distribution of behavioral and neurophysiological sleep patterns in DOC over a 24h period while controlling for environmental factors (by recruiting a group of conscious tetraplegic patients who resided in the same hospital). Methods: We evaluated the distribution of sleep and wakefulness by means of polysomnography (EEG, EOG, EMG) and video recordings in 32 DOC patients (16 Unresponsive Wakefulness Syndrome [UWS], 16 Minimally Conscious State [MCS]) and 10 clinical control patients with severe tetraplegia. Three independent raters scored the patients' polysomnographic recordings. Results: All but one patient (UWS) showed behavioral and electrophysiological signs of sleep. Control and MCS patients spent significantly more time in sleep during the night than during daytime, a pattern that was not evident in UWS. DOC patients (particularly UWS) exhibited less REM sleep than control patients. 44% of UWS patients and 12% of MCS patients did not have any REM sleep, while all control patients (100%) showed signs of all sleep stages and sleep spindles. Furthermore, no sleep spindles were found in 62% of UWS patients and 21% of MCS patients. In the remaining DOC patients who had spindles, their number and amplitude were significantly lower than in controls. Conclusions: The distribution of sleep signs in DOC over 24 hours differs significantly from the normal sleep-wakefulness pattern. These abnormalities of sleep in DOC are independent of external factors such as severe immobility and hospital environment.

中文翻译：

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严重意识障碍中的睡眠：24小时行为和多导睡眠图记录

背景：睡眠-觉醒周期是意识障碍（DOC）的重要诊断标准，可将长时间的DOC与昏迷区分开。特定的睡眠功能（例如睡眠纺锤体的存在）是从DOC恢复的预后的重要标志。基于越来越多的证据表明睡眠与神经元可塑性之间存在联系，了解DOC中的睡眠可能有助于开发新的康复方法。但是，尚缺乏对DOC睡眠的严格控制的研究。在这里，我们的目的是在可靠的评估基础上，在控制环境因素的同时（通过招募居住在同一家医院的一组有意识的四肢瘫痪患者）在24小时内量化DOC中行为和神经生理睡眠模式的分布。方法：我们通过多导睡眠图（EEG，EOG，EMG）和视频记录评估了32名DOC患者（16名无反应性清醒综合征[UWS]，16名最低意识状态[MCS]）和10名重度临床控制患者的睡眠和清醒分布四肢瘫痪。三个独立的评分者对患者的多导睡眠图记录进行了评分。结果：除一名患者外，所有患者均表现出睡眠行为和电生理指标。对照和MCS患者在夜间的睡眠时间要比白天多得多，这在UWS中并不明显。DOC患者（尤其是UWS）的REM睡眠少于对照组。UWS患者中有44％，MCS患者中有12％没有REM睡眠，而所有对照患者（100％）都显示出所有睡眠阶段和睡眠纺锤体的体征。此外，在62％的UWS患者和21％的MCS患者中未发现睡眠纺锤体。在其余具有纺锤体的DOC患者中，其数量和幅度明显低于对照组。结论：DOC在24小时内的睡眠体征分布与正常的睡眠-清醒模式有显着差异。DOC中的这些睡眠异常与严重的行动不便和医院环境等外部因素无关。