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Indian J Psychiatry
Indian J Psychiatry
IJPsy
Indian J Psychiatry
Indian Journal of Psychiatry
0019-5545
1998-3794
Wolters Kluwer - Medknow India

IJPsy-66-649
10.4103/indianjpsychiatry.indianjpsychiatry_120_24
Original Article
Quantitative EEG correlates of ‘Kriya yoga’ benefits for mental health among health care providers
Ojha Pooja
Nebhinani Naresh 1
Chandani Ambika 2
Department of Physiology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
1 Department of Psychiatry, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
2 Indra Yoga Sansthan, Jodhpur, Rajasthan, India
Address for correspondence: Dr. Pooja Ojha, Department of Physiology, All India Institute of Medical Sciences Jodhpur - 342 005, Rajasthan, India. E-mail: drpojha786@gmail.com
7 2024
17 7 2024
66 7 649655
09 2 2024
07 7 2024
07 7 2024
Copyright: © 2024 Indian Journal of Psychiatry
2024
https://creativecommons.org/licenses/by-nc-sa/4.0/ This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
Background:

Health care workers (HCWs) experience abounding physical and mental exhaustion mandating a deliverable solution for their mental health care. Kriya yoga (KY) includes several relaxation techniques and offers a stress-alleviating experience. The objective signature of KY benefits needs to be investigated.

Aim:

To study the effects of KY practice on brain oscillations and perceived stress in health care providers.

Methods:

This prospective interventional study was conducted during coronavirus disease 2019 pandemic. HCWs were enrolled to the intervention group (IG) and control group (CG) after obtaining an informed consent. IG visited the yoga center for learning the KY technique. Electroencephalogram (EEG) was recorded in both the groups, at baseline, and at the end of 6 weeks in the EEG Laboratory. Perceived stress scale (PSS) scores and participants’ subjective response to KY practice were also collected. Paired t-test and independent t-test were used for statistical comparison wherever applicable.

Results:

Age and baseline EEG powers among the IG and CG (N = 25) were statistically comparable. Absolute power analysis revealed a statistically significant increase in alpha and delta powers after 6 weeks of KY practice. The PSS scores revealed a statistically significant decrease in perceived stress after KY practice. Furthermore, 83% of the participants reported the subjective calming effects of KY practice.

Conclusion:

KY practice ensues relaxing effects on the brain, as evident from the EEG absolute power analysis, PSS scores, and participants’ subjective response. As KY is a brief technique, it may be encouraged during short break session among the HCWs for promotive health.

EEG wave power
health care workers
Kriya yoga
QEEG
yoga
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pmcINTRODUCTION

Health care workers (HCWs) are at heightened risk of acquiring infection while managing the patients. The unprecedented situation of widespread communicable infections such as the recent coronavirus disease 2019 (COVID-19) pandemic contribute to further apprehension, considerable anxiety, and mental stress among the first line warriors, making them prone to the long-term effects of adverse psychological environment.[1] A recent national survey, by Young and colleagues, reported that nearly half of the HCWs agreed to have worse psychiatric symptoms including suicidal tendencies during the COVID-19 pandemic.[2] Commensurately, mental health issues of the HCWs necessitate attention and seek a deliverable solution. In a recent review, Bohlken et al.[3] investigated the mental health problems in healthcare workers and prevalent ways of coping with stress. They concluded that conversant interventions and coping strategies are essential. Of note, Patanjali’s Kriya yoga (KY), an amalgamation of several relaxation techniques, has been found to offer a holistic stress alleviating experience.[4]

Electroencephalogram (EEG) is a feasible, objective tool to investigate the cerebral arousal. Hence, KY effects on the brain can be estimated through the frequency and amplitude changes of the waves.[5] In addition to arousal, an increase in EEG waves reflects several cognitive benefits. The alpha waves are representative of the thalamocortical networking between neurons and predominate during a relaxed but awake mental state. Alpha waves have been correlated with physiologic behaviors such as reduction in pain and discomfort,[6] positive correlation to speed of information retrieval with cognitive task, and efficient memory performance.[7] The alpha waves have been reported to inhibit irrelevant sensorimotor processing during cognitive task performance.[8] The alpha oscillations also contribute to sentence processing besides their role in domain-general working memory.[9] An increase in alpha is also related to a subjective feeling of calmness. Beta waves, in contrast to alpha, represent an increased cortical activity as observed during task completion. Beta waves correlate with higher arithmetic calculation ability.[10] Theta rhythm is seen with a repetitive monotonous task that barely requires attention for its completion.[11] In addition, theta is also found to reduce anxiety and play a role in building memories.[12] Delta waves have been reported in meditators and also found to be linked to cognitive processing. Delta bands are important contributors to the evoked cortical potentials.[13]

Though yogic techniques have been studied for their benefits, the reports on the objective signature to mental health benefits of KY practice have remained scarce. Hence, the present study was conducted to ascertain the effects of 6 weeks of KY practice on EEG waves, perceived stress, and subjective response to KY practice in the HCWs during the COVID-19 pandemic.

METHODS

Participants

HCWs of both sexes, in the age group of 20–45 years, working in a tertiary care hospital were approached. The control group (CG) comprised HCWs who were age- and gender-matched and agreed to participate in the study. The exclusion criteria for the intervention/Yoga group (IG) and CG were chronic medical condition, subjects already practicing regular yoga, psychiatric disorders, and substance use disorders. The study was approved by the Institutional Ethics Committee of the institute, and informed consent was obtained from the participants. The work was registered under the clinical trial registry of India (CTRI registration number: CTRI/2021/03/032410).

Intervention

The entire set of sequences in ‘Kriya yoga’ [Figure 1] were taught by the yoga expert in a physical class. The KY slot was dedicated for research participants only during those hours. Since the participants were yoga naïve, minimum one in-person/physical KY session with the expert was mandatory. The physical class helped the participants learn the correct postures, breathing method, and chanting technique and clear doubts about the KY technique from the yoga expert. Subsequently, the participants received an audio narration of the skill and were required to practice the technique every day for 6 weeks. Participants in the waitlist control group were not given any intervention during the study period. They were offered the KY practice after the study was completed.

Figure 1 Components of KY

Experimental setup: Precautions were taken to ensure social distancing and avoid unnecessary physical contacts during the study. Participants were recruited through digital advertisements for the intervention and control groups. The advertisement was shared on WhatsApp groups with the health care providers. The advertisement briefly explained the requirements for the participants. They were required to undergo a structured protocol. The demographic data were collected through Google Forms.

EEG recording and perceived stress scale (PSS) scores were obtained before KY intervention and after the last practice session, that is, at the end of 6 weeks from beginning of KY.

The PSS questionnaire was also administered through Google Forms.

EEG recording and analysis

EEG was recorded through a wireless 14 channel 128 Hz Emotiv EPOC acquisition headset.

The headset device was connected to a laptop via a USB receiver and Bluetooth wireless connection. EEG was acquired for a duration of 15 minutes from 14 channels (AF3, AF4, F7, F8, F3, F4, FC5, FC6, T7, T8, P7, P8, O1, and O2) in the awake and eyes-closed states. The sensors were positioned through the flexible arms of the headset according to the international 10-20 system.[14] The standard reference electrodes for the device were positioned at P3 and P4 regions. The headset used a common mode sensor as an absolute voltage reference (positioned at P3) and a driven right leg sensor (positioned at P4) to adjust the refence level through a feedback cancellation of common mode potential.

Live display on the laptop screen and storage was accomplished through an Emotiv compatible software.

The stored data were imported to EEGLAB software for preprocessing and analysis.[15] The preprocessing comprised rereferencing, data filtering, and artifact removal. The data were rereferenced to the common average. The raw signals were filtered with a high-cutoff filter at 30 Hz and a low-cutoff filter at 1 Hz. In addition, the line noise of 50 Hz was also removed. The ocular and muscle artifacts were eliminated through the independent component analysis ‘runica’ function of the EEGLAB. The data were not trimmed as it was a resting-state EEG without any discrete events during the recording.

After filtration, the signal was analyzed to determine the spectral power in frequency bins of beta (13–30 Hz), alpha (8–13 Hz), theta (4–8 Hz), and delta (1–4 Hz) from temporal (T7, T8), parietal (P7, P8), occipital (O1, O2), frontal (AF3, AF4, F3, F4, F7, F8), and central regions (FC5, FC6). The spectral analysis aimed to obtain the spectrum of EEG data by transforming the signals from the time domain to frequency domain. This was performed through Fourier transform using the Welch method with a nonoverlapping 2 s window. The Fourier transform technique breaks the time-series signals and adds to a set of sine waves.[16] The absolute power in all frequency bins was then determined for comparison.

Perceived stress scale (PSS): The PSS was used to assess the impact of uncontrollable or unpredictable life events leading to stress. In this 10-item Likert-type scale, responses were scored on a 5-point scale from 0 (“never”) to 4 (“very often”). The PSS scores range from 0 to 40, and higher scores indicate higher stress levels. The PSS is a reliable measure of stress and correlates adequately with social anxiety and life experiences.[1718]

Participants’ subjective feeling toward this methodology: Feedback related to overall subjective experience was collected at the end of the study from all participants through Google Forms.

Data analysis

Data were analyzed using SPSS software version 20. The continuous and categorical data were represented as mean with standard deviation, and numbers and percentage, respectively. Paired t-test was used to compare the parameters before and after 6 weeks of intervention and control in two groups. Independent t-test was used to compare parameters between IG and CG.

RESULTS

Twenty-five male HCWs participated in the study. The IG (n = 12) comprised 3 (25%) nursing officers, 2 (16.7%) lab technicians, 4 (33.3%) doctors, and 3 (25%) ward attendants with a mean age of 32.3 years. The CG (n = 13) comprised 3 (23.1%) nursing officers, 3 (23.1%) lab technicians, 4 (30.7%) doctors, and 3 (23.1%) ward attendants with a mean age of 27.6 years. There was statistically no difference in the age between the IG and CG (P = 0.074). The mean absolute powers of beta, alpha, theta, and delta waves in occipital, temporal, parietal, central, and frontal regions in the EEG were calculated in the awake and eyes-closed states. The difference in the mean absolute powers of different waves in various scalp locations was not statistically significant among the IG and CG in baseline recording [Figure 2].

Figure 2 Comparison of absolute power of EEG waves (µV2) in baseline recording among intervention and control groups in a) frontal, b) central, c) temporal, d) occipital, and e) parietal

The comparison of power of EEG waves before and after 6 weeks of intervention and control is presented in Table 1. The IG demonstrated a statistically significant increase in alpha power in all five regions and delta power in central, parietal, temporal, and occipital regions. Changes in beta and theta powers were not statistically significant at the end of the training session. In contrast, there was no statistically significant change in EEG power in the control group after 6 weeks. Radar charts [Figure 3] depict the differences in mean absolute powers of EEG waves at different locations before and after KY. The comparison of scores of PSS after 6 weeks of intervention and control among the two groups is presented in Figure 4. Participants’ subjective response to the intervention showed that 50% of the participants could appreciate the relaxation benefits of KY since the first session, and the number increased to 83% of participants at the end of 6 weeks of practice. The waitlist control group was offered KY at the end of the study.

Figure 3 Differences in mean absolute powers of EEG waves (µV2) at different locations before and after KY (error bars represent the standard error)

Figure 4 Comparison of mean PSS scores after 6 weeks of intervention and control between the two groups. *Statistically significant with paired t-test (P < 0.001)

Table 1: Absolute power of EEG waves before and after 6 weeks of intervention and control

Regions and rhythms	Absolute power of EEG waves before and after 6 weeks of KY	
	Control Group	Intervention Group	
	Pre	Post	P	Pre	Post	P*	
F Beta	0.35 (0.239)	0.452 (0. 58)	0.740	0.304 (0.096)	0.391 (0.197)	0.267	
F Alpha	10.61 (3.08)	14.35 (3.28)	0.094	12.141 (4.969)	25.819 (6.440)	<0.001	
F Theta	1.66 (1.22)	2.1 (1.207)	0.653	1.560 (0.765)	1.716 (0.708)	0.778	
F Delta	4.53 (2.07)	3.68 (1.99)	0.251	2.751 (1.352)	4.580 (2.927)	0.078	
C Beta	0.490 (0.411)	0.690 (0.707)	0.453	0.333 (0.112)	0.985 (0.845)	0.085	
C Alpha	7.22 (1.794)	8.4 (3.161)	0.105	7.68 (3.42)	22.7 (10.03)	0.002	
C Theta	1.246 (0.562)	1.426 (0.724)	0.268	1.23 (0.610)	1.422 (0.441)	0.434	
C Delta	2.611 (0.355)	3.212 (0.826)	0.102	2.49 (0.169)	3.69 (0.659)	0.004	
P Beta	0.693 (0.325)	0.566 (0.564)	0.469	0.411 (0.151)	0.259 (0.062)	0.087	
P Alpha	12.35 (2.22)	17.09 (2.72)	0.053	11.802 (2.45)	42.06 (4.41)	<0.001	
P Theta	1.187 (0.405)	1.219 (0.132)	0.873	1.452 (0.502)	1.328 (0.009)	0.524	
P Delta	2.07 (.975)	1.97 (2.2)	0.936	1.526 (0.464)	3.37 (1.18)	0.008	
T Beta	0.484 (.361)	0.663 (0.932)	0.266	0.841 (0.3688)	1.08 (0.223)	0.051	
T Alpha	9.396 (2.54)	9.143 (3.118)	0.754	9.950 (4.468)	63.899 (37.49)	0.009	
T Theta	1.363 (0.411)	1.143 (0.667)	0.588	1.294 (0.458)	1.986 (0.785)	0.119	
T Delta	6.563 (0.984)	5.898 (1.682)	0.132	6.84 (1.29)	8.01 (1.164)	0.028	
O Beta	4.57 (1.1)	5.518 (1.79)	0.364	4.65 (0.168)	4.73 (0.579)	0.729	
O Alpha	44.16 (5.31)	44.82 (5.54)	0.446	45.98 (3.97)	76.114 (8.4)	<0.001	
O Theta	1.343 (0.084)	2.313 (0.975)	0.055	1.33 (0.188)	1.91 (0.81)	0.072	
O Delta	4.46 (1.4)	5.4 (1.32)	0.381	3.37 (0.694)	5.48 (1.898)	0.030	
F; Frontal: C; Central: P; Parietal: T; Temporal: O; Occipital: The mean absolute power is expressed in μV2. The numbers in parenthesis represent standard deviation. *Paired t-test

DISCUSSION

The objective signature of the effects of KY training on brain waves was demonstrated through the quantitative measures of EEG. Our key finding was an increase in alpha power in all regions after 6 weeks of practice. Previously, Bapat in 2016 studied KY as per Patanjali Yoga Sutra.[19] They found that KY helps achieve a comprehensive control of bodily functions through the ensued psychophysiological changes and it is a step toward achieving a calm state of mind, which is essential for practice. Anand and colleagues[20] studied brain electrical activity in yogis practicing meditation and yogis with raised pain threshold. They reported that during meditation, all yogis had alpha oscillations with a heighted amplitude. The yogis with higher pain thresholds also manifested alpha oscillations prior to and during immersion of their hand in cold water. Takahashi studied the changes in EEG activity in meditation. They found slow alpha power and fast theta power in the frontal region during meditation.[21]

Our finding also corroborates with additional reported studies. Fifty minutes of Yogic practices with breath modulation training over a period of 1 month was reported to enhance alpha waves. The training included fast and slow breathing exercises, followed by 30 min of meditation and relaxation with attention focused at breathing movements. EEG assessment revealed a bilateral increase in alpha wave activity over occipital and prefrontal areas.[22] In another study, the effects of asana-based Yoga and pranayama practices with slow and fast breathing exercises in police trainees revealed a significant increase in alpha with asana-based yoga and asana with pranayama-based yoga, but not with only pranayama.[23] Another group of researchers found an increase in alpha and beta waves with pranayama practice in regular yoga practitioners.[24] In addition, it is known that during relaxed wakefulness, the rhythmic activity predominates in the alpha frequency range. Therefore, with mental relaxation and stress reduction, the increased alpha rhythm may imply a reduced cortical activity and enhanced thalamic signaling. Interestingly, the alpha index and mean power in the alpha range have been reported to be higher with meditation practices and among adults practicing yoga nidra, respectively.[2526] The differences in the reported findings of the studies probably suggest combining different asana-based and pranayama-based yogic exercises. Perceptibly, yogic benefits are more feasible with a combination of breathing and relaxation techniques. In this context, it can be suggested that KY practice has shown an increase in the alpha power, probably owing to the combination of asana and pranayama techniques.

Though we did not find a statistically significant increase in the theta activity at the end of 6 weeks of KY training, an increase in theta activity has been reported with Bramari pranayama and also with asana-pranayam trainings.[2327] An improvement in visual and auditory reaction time was also found with asana-pranayam trainings, along with the theta power, with a combined asana-pranayam training for 6 months.[23] The participants reported an improved emotional balance and reduced anxiousness.[23] Kriya-based yoga practice including slow and fast breathing with meditation and contemplation has reportedly enhanced theta and alpha waves in regular practitioners. In contrast to kriya-based yoga, modified hatha-yoga training for 8 weeks in participants with stress has been reported to increase alpha and delta activity in anterior two-third of the brain compared to the pretraining baseline.[28] Hatha yoga includes asanas (physical poses), pranayams (breathing techniques), and meditation. The findings suggested an increase in regional neuronal coactivation and integration with improvement in cognitive flexibility as depicted by the performance in cognitive tasks.[28] The increase in delta power in the reported studies is aligned to our results. Several studies also reported an increase in the beta waves after training in pranayama and yoga. Sudarshan KY and pranayama practice for 1 year revealed high beta waves with interspersed alpha waves depicting the possibility of alertness with intermittent relaxations.[29]

The findings of the present study may be interpreted in the light of the limitations. The sample size was not estimated for the present study, and the results are based on a small population of male HCWs. The scanty demographic information of the participants limits generalization of the findings. Though we did not restrict the inclusion of female HCWs, the attributable cause for limited participation from HCWs could be the peak of the second wave of the COVID-19 pandemic during which this study was conducted. Hence, KY benefits cannot be generalized for females from the present results. The other limitations comprise nonrandomization of the IG and CG, though precautions were taken to keep both the groups comparable. In addition, a structured assessment tool was not used for recruitment of participants. To conclude, the KY practice has shown relaxing effects with enhancing alpha and delta waves at the end of 6 weeks of practice among HCWs. It can be suggested that for promotive health, a combination of different yogic practices such as deep relaxation (meditation), physical postures (asanas), and breath modulation practices (pranayama) would enable a more holistic benefit for the mind and body and should be encouraged among the HCWs.

Ethics approval

Ethical approval was sought from the Institute’s ethical committee before commencement of the work. The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Consent

Informed consent was obtained from all participants prior to inclusion in the study.

Financial support and sponsorship

The authors acknowledge Department of Science and Technology, Government of India for financial support vide Reference No. (DST/SATYAM/COVID-19/2020/381).

Conflicts of interest

There are no conflicts of interest.
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