Dream & Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM - Hôpital du Sacré-Coeur de Montréal, Canada; Department of Neuroscience, Université de Montréal, Montréal, Québec, Canada.
Dream & Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM - Hôpital du Sacré-Coeur de Montréal, Canada; Department of Biomedical Sciences, Université de Montréal, Montréal, Québec, Canada.
Sleep Med. 2018 Oct;50:113-131. doi: 10.1016/j.sleep.2017.10.003. Epub 2017 Nov 4.
Idiopathic nightmares are a common disturbance of rapid eye movement sleep (REM) sleep, but studies of comorbid pathologies and sleep architecture suggest that non-REM (NREM) sleep is also affected. Sleep spindles are a NREM sleep characteristic associated with both pathophysiology and sleep-dependent memory consolidation, yet they have not been evaluated in frequent nightmare recallers. The morning naps of 38 participants with frequent idiopathic nightmares (mean age: 23.7 ± 3.78 years) and 25 age- and sex-matched controls (23.9 ± 3.65 years) were recorded and their sleep evaluated. A custom spindle detector assessed NREM sleep stage 2 (N2) sleep spindles on six electroencephalogram (EEG) derivations (F3, F4, C3, C4, O1, and O2) for density (number spindles/N2 time), mean frequency, and amplitude. Total spindles (10-16 Hertz (Hz) range), slow spindles (10-12.79 Hz), and fast spindles (12.8-16 Hz) were all assessed separately. Compared with the Control group, the Nightmare group had longer N2 sleep latency and a marginally greater %N2 sleep. The Nightmare group also had a lower than normal density of slow spindles in most EEG derivations, a higher density of fast spindles in frontal derivations, and an elevated fast spindle oscillatory frequency-"faster fast" spindles-mainly in central derivations. These differences withstood controls for pre-existing group differences in depression. Correlational analyses demonstrated a further pattern of group differences by which higher pathology scores were associated with higher slow spindle densities and slower spindle frequencies for the Nightmare but not the Control group. A similar pattern was observed for some dream content measures, ie, the Nightmare group showed positive correlations of slow spindle density with dreamed fear and word count and negative correlations with dreamed positive emotion. Conversely, the Control group showed opposite trends. Results thus demonstrate abnormalities in the composition of N2 sleep-and especially in N2 spindles-among frequent nightmare recallers and link these abnormalities to both trait (psychopathology) and state (dream content) factors. Spindle findings for psychopathology resemble, but are not identical with, previous findings for patients with major depression, social anxiety, and schizophrenia and are thus consistent with an explanation implicating spindles as trait markers of psychopathology. Correlational analyses go beyond a trait explanation to suggest several possible state-based explanations involving memory consolidation mechanisms, specifically, the possibility that spindles index either emotional or verbal task-based processes.
特发性噩梦是快速眼动睡眠（REM）睡眠常见的障碍，但合并症的病理生理学和睡眠结构的研究表明，非快速眼动（NREM）睡眠也受到影响。睡眠梭形波是与病理生理学和睡眠依赖性记忆巩固相关的 NREM 睡眠特征，但它们尚未在频繁噩梦回忆者中进行评估。38 名有频繁特发性噩梦（平均年龄：23.7±3.78 岁）的参与者和 25 名年龄和性别匹配的对照组（23.9±3.65 岁）的早晨小睡被记录下来，并对他们的睡眠进行了评估。一个定制的纺锤体探测器在六个脑电图（EEG）衍生（F3、F4、C3、C4、O1 和 O2）上评估 N2 睡眠阶段 2（N2）睡眠纺锤体的密度（纺锤体/ N2 时间的数量）、平均频率和振幅。总纺锤体（10-16 赫兹（Hz）范围）、慢纺锤体（10-12.79 Hz）和快纺锤体（12.8-16 Hz）分别进行评估。与对照组相比，噩梦组的 N2 睡眠潜伏期较长，N2 睡眠时间百分比略高。噩梦组在大多数 EEG 衍生中慢纺锤体的密度也低于正常水平，在前额衍生中快纺锤体的密度较高，并且快纺锤体的振荡频率升高——“更快的快”纺锤体——主要在中央衍生中。这些差异在控制抑郁等先前存在的组间差异方面具有统计学意义。相关分析表明，通过更高的病理评分与噩梦组的慢纺锤体密度更高和纺锤体频率更慢相关，而与对照组无关，存在进一步的组间差异模式。一些梦境内容测量也表现出类似的模式，即噩梦组的慢纺锤体密度与梦境中的恐惧和单词数呈正相关，与梦境中的积极情绪呈负相关。相反，对照组则呈现相反的趋势。结果表明，在频繁噩梦回忆者中，N2 睡眠的组成——特别是 N2 纺锤体——存在异常，并将这些异常与特质（精神病理学）和状态（梦境内容）因素联系起来。纺锤体与精神病理学的关联与以前对重度抑郁症、社交焦虑症和精神分裂症患者的研究相似，但并不相同，因此支持将纺锤体作为精神病理学特征标志物的解释。相关分析超越了特质解释，提出了几种可能涉及记忆巩固机制的基于状态的解释，具体来说，纺锤体可能指数情感或基于任务的过程。
