Investigation of sleep spindles’ oscillations is increasingly considered as a major avenue of inquiry in analyzing the microarchitecture of sleep. Previous studies highlight a strong mutual interaction between sleep and stress. In the present study, we investigated the effects of multiple stresses, provoked by animal immobilization in the narrow Plexiglas boxes with additional stress by placing some stones on the floor. Male Wistar rats ( n = 14) were subjected to 2 h of immobilization per day in a narrow, uneven and stony place for 3 consecutive days. The electroencephalogram (EEG) was recorded with stainless steel screw electrodes placed over the skull and the electromyogram (EMG) was recorded from dorsal neck muscles. The sleep stages were recorded during 2 h before and 2 h after stress exposure for 3 days. Apart from sleep stages’ variations, sleep spindles’ density as well as their time- and frequency-domain characteristics were investigated rigorously by a semi-automatic sleep scoring method developed in MATLAB. Results indicate that multiple stresses containing immobilization as well as physical stress attenuate rapid eye movement sleep (REM). However, the stress effect on spindles is more sophisticated in NREM stages. Although spindle density does not undergo a significant change, spindle amplitude and sigma power of EEG during spindles raised significantly. Besides, a decrease in the mean frequency of spindles depicts a dramatic multiplication in delta slow oscillations. An especially mixed immobility including psychological and physical stress which we applied could affect sleep stability through an alteration in the sleep spindles’ amplitude and frequency but not the density of spindles and also through a reduction in REM sleep.

中文翻译：

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大鼠固定应激模型对 REM 睡眠和睡眠纺锤波特性的改变

对睡眠纺锤波振荡的研究越来越被认为是分析睡眠微体系结构的主要调查途径。先前的研究强调了睡眠和压力之间的强烈相互作用。在本研究中，我们调查了多种压力的影响，这些压力是由动物固定在狭窄的有机玻璃盒中引起的，并通过在地板上放置一些石头来增加压力。雄性 Wistar 大鼠 (n = 14) 连续 3 天在狭窄、不平坦和多石的地方每天固定 2 小时。用放置在颅骨上的不锈钢螺旋电极记录脑电图 (EEG)，并从颈背肌肉记录肌电图 (EMG)。在压力暴露前 2 小时和后 2 小时内记录了 3 天的睡眠阶段。除了睡眠阶段的变化，通过在 MATLAB 中开发的半自动睡眠评分方法，对睡眠纺锤波的密度及其时域和频域特性进行了严格研究。结果表明，包含固定以及身体压力的多重压力会减弱快速眼动睡眠 (REM)。然而，在 NREM 阶段对主轴的应力影响更为复杂。虽然纺锤体密度没有发生显着变化，但纺锤体期间脑电图的纺锤体振幅和西格玛功率显着升高。此外，纺锤体平均频率的降低描绘了 delta 慢振荡的显着倍增。