Study Objectives The present study investigated the hypothesis that subjects with primary sleep bruxism (SB) exhibit masseter and cortical hyperactivities during quiet sleep periods that are associated with a high frequency of rhythmic masticatory muscle activity (RMMA). Methods Fifteen SB and ten control participants underwent polysomnographic recordings. The frequencies of oromotor events and arousals and the percentage of arousals with oromotor events were assessed. Masseter muscle tone during sleep was quantified using a cluster analysis. Electroencephalography power and heart rate variability were quantified and then compared between the two groups and among sleep stages. Results The frequency of RMMA and percentage of arousals with RMMA were significantly higher in SB subjects than in controls in all stages, while these variables for nonrhythmic oromotor events did not significantly differ between the groups. In SB subjects, the frequency of RMMA was the highest in stage N1 and the lowest in stages N3 and R, while the percentage of arousals with RMMA was higher in stage N3 than stages N1 and R. The cluster analysis classified masseter activity during sleep into two clusters for masseter tone and contractions. Masseter muscle tone showed typical stage-dependent changes in both groups but did not significantly differ between the groups. Furthermore, no significant differences were observed in electroencephalography power or heart rate variability between the groups. Conclusion Young SB subjects exhibited sleep stage-dependent increases in the responsiveness of RMMA to transient arousals, but did not show masseter or cortical hyperactivity during sleep.

中文翻译：

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原发性睡眠磨牙症年轻受试者强直咬肌和皮质活动的睡眠阶段依赖性变化

研究目标 本研究调查了以下假设：原发性睡眠磨牙症 (SB) 受试者在安静睡眠期间表现出咬肌和皮质过度活跃，这与高频率的节律性咀嚼肌活动 (RMMA) 相关。方法 15 名 SB 和 10 名对照参与者接受了多导睡眠图记录。评估了口腔运动事件和觉醒的频率以及伴有口腔运动事件的觉醒百分比。使用聚类分析量化睡眠期间的咬肌张力。量化脑电图功率和心率变异性，然后比较两组和睡眠阶段之间的差异。结果 SB 受试者的 RMMA 频率和 RMMA 唤醒百分比在所有阶段均显着高于对照组，而这些非节律性口腔运动事件的变量在各组之间没有显着差异。在SB受试者中，RMMA的频率在N1阶段最高，在N3和R阶段最低，而在N3阶段RMMA唤醒的百分比高于N1和R阶段。聚类分析将睡眠期间的咬肌活动分类为咬肌音和收缩的两个集群。咬肌张力在两组中显示出典型的阶段依赖性变化，但组间没有显着差异。此外，两组之间的脑电图功率或心率变异性未观察到显着差异。结论 年轻的 SB 受试者表现出 RMMA 对短暂唤醒的反应性的睡眠阶段依赖性增加，但在睡眠期间没有表现出咬肌或皮质过度活跃。