Electrophysiological Evidence of Local Sleep During Yoga Nidra Practice

Abstract

Background and ObjectivesYoga nidra is a technique sages use to self-induce sleep. Classically, sleep is characterized by three cardinal electrophysiological features, namely, electroencephalography (EEG), electromyography (EMG), and electrooculography (EOG). As the literature on electrophysiological characterization of Yoga nidra is lacking, it is not known whether it is a sleep or awake state. The objective of the study was to electrophysiologically characterize yoga nidra practice.Materials and MethodsThirty subjects underwent five initial supervised yoga nidra sessions and then continued practice on their own. The subjects completed their sleep diaries for 2 weeks before and during the intervention. The electrophysiological characterization was done after 2 weeks of yoga nidra practice using 19 EEG channels polysomnography for pre-yoga nidra, yoga nidra practice and post-yoga nidra. Polysomnographic data were scored for sleep-wake stages as per standard criteria. Power spectral density (PSD) was calculated from various frequency bands in different time bins. EEG data were grouped by areas, namely, central, frontal, prefrontal, parietal, temporal, and occipital in time bins. Sleep diary parameters were also compared for pre-post-yoga nidra training.ResultsAfter 2 weeks of yoga nidra practice, awake was scored throughout the session (n = 26). PSD results (mean difference in dB between different time bins; P value) showed significant changes. When compared to pre-yoga nidra, there was an increase in delta power in the central area (1.953; P = 0.033) and a decrease in the prefrontal area (2.713; P = 0.041) during yoga nidra. Sleep diary showed improvement in sleep duration (P = 0.0001), efficiency (P = 0.0005), quality (P = 0.0005), and total wake duration (P = 0.00005) after 2 weeks of practice.Interpretations and ConclusionsYoga nidra practice in novices is electrophysiologically an awake state with signs of slow waves locally, often referred to as local sleep.Clinical TrialClinical Trial Registry of India, http://www.ctri.nic.in/Clinicaltrials/pmaindet2.php? trialid = 6253, 2013/05/003682.

Improved Sleep, Cognitive Processing and Enhanced Learning and Memory Task Accuracy with Yoga Nidra Practice in Novices

“…Slow waves during sleep have been directly or indirectly linked to synaptic strength as a part of synaptic homeostasis theory 20 . Local sleep seen during the yoga nidra practice is also found to enhance task performance 3,21 . We found enhanced reaction time of all tests with no reduction in accuracy after the practice as compared to baseline.…”

“…Yoga nidra practice by novices is known to improve sleep in insomnia patients 1,2,5,15 . In healthy subjects the practice showed evidence of local sleep in certain areas of brain while the subject was behaviorally awake 3 . Our results showed an objective improvement in night time sleep after yoga nidra practice in novices.…”

“…Individuals required to take critical decisions require optimized cognitive functioning. There is evidence that improved sleep can enhance cognitive functioning and partial sleep deprivation reduces it 3 .…”

Improved sleep, cognitive processing and enhanced learning and memory task accuracy with Yoga nidra practice in novices

“…The decomposition of signal to frequency bands were done using Fourier transforms [27]. The ranges of the bands were delta (1-4Hz), theta1 (4-6Hz), theta2 (6-8Hz), alpha1 (8-10Hz), alpha2 (10-12.5Hz) and beta (13-30Hz) [6]. The features used in the EEG signal analysis were relative-band-power and ratios between the bands [31].…”

Brain Connectivity Changes in Meditators and Novices during Yoga Nidra: A Novel fMRI Study

“…Further, there is an assertion that one hour of Yoga Nidra (YN) practice can potentially yield benefits equivalent to that of 3-4 hours of traditional sleep 1 . Interestingly, YN practice has also shown benefits in improving the outcomes related to insomnia and sleep quality in several clinical studies [20][21][22][23] .…”