Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Italy.
Rasa-Nidrâ Yoga International, Eyragues, France.
Int J Yoga Therap. 2021 Jan 1;31(1). doi: 10.17761/2021-D-20-00014.
Nidrâ yoga is an ancient yogic practice capable of inducing altered states of consciousness characterized by deep relaxation, strong concentration, acute self-awareness, and joy. In modern contemplative neuroscience language, it is known by the name yoga nidra, and few studies have investigated its phenomenological and psychophysiological effects. Six healthy volunteers (four females aged 31-74) performed 12 yoga nidra sessions guided by an expert during a 6-day retreat. Each session consisted of 10 minutes in a resting state (baseline) followed by 2 hours of yoga nidra. Psychometric data regarding dissociative experiences (Clinician Administered Dissociative States Scale) and the state of consciousness (Phenomenology of Consciousness Inventory) were collected after baseline and yoga nidra, while high-density EEG was recorded during the entire session. During nidra sessions, no sleep hallmarks (i.e., K-complexes and sleep spindles) were detected by the EEG in any subject. Psychometric data we re analyzed using a Wilcoxon signed-rank test corrected with the false discovery rate approach for multiple comparisons. Compared to baseline, yoga nidra practice was related to: (1) increased dissociative effects (p = 0.022); (2) perception of being in an altered state of consciousness (p = 0.026); (3) alterations in perceived body image (p = 0.022); (4) increased "meaningfulness" attributed to the experience (p = 0.026); (5) reduced rational thinking (p = 0.029); and (6) reduced volitional thought control (p = 0.026). First-person experience is discussed in relation to descriptive EEG power spectral density analysis, which was performed in one subject because of severe EEG artifacts in the other recordings; that subject showed, compared to baseline: (1) early increase of alpha and beta power, followed by a progressive widespread reduction; (2) widespread early increase of theta power, followed by a progressive reduction; and (3) widespread increase of gamma power in the latest stages. The present preliminary results enrich the knowledge of yoga nidra, elucidating its phenomenology and suggesting some psychophysiological correlates that future studies may address.
尼德拉瑜伽是一种古老的瑜伽练习，可以诱导出具有深度放松、强烈专注、敏锐自我意识和喜悦的意识改变状态。用现代沉思神经科学的语言来说，它被称为瑜伽睡眠，很少有研究调查它的现象学和心理生理效应。六名健康志愿者（四名女性，年龄 31-74 岁）在为期六天的静修期间，由一名专家指导进行了 12 次瑜伽睡眠。每次会议包括 10 分钟的休息状态（基线），然后是 2 小时的瑜伽睡眠。在基线和瑜伽睡眠后收集关于分离体验的心理测量数据（临床管理的分离状态量表）和意识状态（意识现象学清单），而高密度 EEG 在整个会议期间记录。在睡眠过程中，没有睡眠特征（即 K-复合物和睡眠纺锤波）被任何受试者的 EEG 检测到。心理测量数据使用 Wilcoxon 符号秩检验进行分析，该检验使用错误发现率方法进行了多次比较的校正。与基线相比，瑜伽睡眠练习与以下方面有关：（1）增加分离效果（p = 0.022）；（2）感知到处于意识改变状态（p = 0.026）；（3）感知到的身体形象改变（p = 0.022）；（4）增加体验的“意义”（p = 0.026）；（5）减少理性思维（p = 0.029）；和（6）减少意志思维控制（p = 0.026）。第一人称体验是在一个受试者的描述性 EEG 功率谱密度分析的基础上进行讨论的，因为其他记录中的 EEG 伪影严重；与基线相比，该受试者表现出：（1）早期增加阿尔法和贝塔功率，随后广泛减少；（2）早期广泛增加 theta 功率，随后广泛减少；（3）晚期广泛增加伽马功率。本初步结果丰富了瑜伽睡眠的知识，阐明了其现象学，并提出了一些未来研究可能涉及的心理生理相关性。
