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Yoga Nidra Relaxation Increases Heart Rate Variability and is Unaffected by a Prior Bout of Hatha Yoga
Abstract
Objective:
The measurement of heart rate variability (HRV) is often applied as an index of autonomic nervous system (ANS) balance and, therefore, myocardial stability. Previous studies have suggested that relaxation or mind-body exercise can influence ANS balance positively as measured by HRV but may act via different mechanisms. No studies, to the authors' knowledge, have examined the acute response in HRV to interventions combining relaxation and mind-body exercise. The objective of this study was to compare the acute HRV responses to Yoga Nidra relaxation alone versus Yoga Nidra relaxation preceded by Hatha yoga.
Design:
This was a randomized counter-balanced trial.
Setting:
The trial was conducted in a university exercise physiology laboratory.
Subjects:
Subjects included 20 women and men (29.15±6.98 years of age, with a range of 18-47 years).
Interventions:
Participants completed a yoga plus relaxation (YR) session and a relaxation only (R) session.
Results:
The YR condition produced significant changes from baseline in heart rate (HR; beats per minute [bpm], p<0.001) and indices of HRV: R-R (ms, p<0.001), pNN50 (%, p=0.009), low frequency (LF; %, p=0.008) and high frequency (HF; %, p=0.035). The R condition produced significant changes from baseline in heart rate (bpm, p<0.001) as well as indices of HRV: R-R (ms, p<0.001), HF (ms(2), p=0.004), LF (%, p=0.005), HF (%, p=0.008) and LF:HF ratio (%, p=0.008). There were no significant differences between conditions at baseline nor for the changes from baseline for any of the variables.
Conclusions:
These changes demonstrate a favorable shift in autonomic balance to the parasympathetic branch of the ANS for both conditions, and that Yoga Nidra relaxation produces favorable changes in measures of HRV whether alone or preceded by a bout of Hatha yoga.
... When practiced regularly, it provides physical, mental, and intellectual health to the individual (Kumar & Aanand, 2016;Pal, 2022). When the mechanism of action is examined, it is stated that yoga nidra activates various brain regions (Ferreira-Vorkapic et al., 2018;Markil et al., 2012;Pal, 2022;Werner et al., 2015). Yoga nidra creates a response in the brain that is integrated by the hypothalamus, reducing sympathetic (excitation) nervous system activity and increasing parasympathetic (relaxation) nervous system function (Ferreira-Vorkapic et al., 2018;Markil et al., 2012;Werner et al., 2015). ...
... When the mechanism of action is examined, it is stated that yoga nidra activates various brain regions (Ferreira-Vorkapic et al., 2018;Markil et al., 2012;Pal, 2022;Werner et al., 2015). Yoga nidra creates a response in the brain that is integrated by the hypothalamus, reducing sympathetic (excitation) nervous system activity and increasing parasympathetic (relaxation) nervous system function (Ferreira-Vorkapic et al., 2018;Markil et al., 2012;Werner et al., 2015). It is also stated that yoga nidra activates the parasympathetic nervous system in the body with high cardiac vagal control, which leads to a decrease in anxiety and an increase in sleep quality (Werner et al., 2015). ...
... In addition, although the study did not directly evaluate the level of mobilization, it reported that it increased the self-efficacy of mothers describing their conscious effort in education (Esencan & Rathfisch, 2023). Yoga nidra activates several brain regions (Ferreira-Vorkapic et al., 2018;Markil et al., 2012), decreases sympathetic activity, and increases parasympathetic activity with high cardiac vagal control, resulting in increased physical subjective and objective sleep quality despite mental alertness, decreased anxiety and pain, and increased mobilization (Ferreira-Vorkapic et al., 2018;Markil et al., 2012;Werner et al., 2015). Since mobilization is a behavior that requires conscious awareness, it can be said that yoga nidra is therefore effective at this stage. ...
Aim: This study aims to investigate the effect of yoga nidra on pain, mobilization, first walking distance, and care satisfaction. Methods: This is a randomized controlled trial. Data were collected between 01 October–28 December 2023. Sample of the study consisted of 128 women (yoga nidra: 64, control: 64) who gave birth by cesarean section. Women were randomly assigned to the groups as 1:1. The yoga nidra group received a 30-minute yoga nidra session before the first mobilization after cesarean section. Yoga nidra was not applied to the control group. The primary outcomes of the study were the mean scores of the Visual Analogue Scale (VAS) for pain, Patient Mobility Scale (PMS), Observer Mobility Scale (OMS), and walking distance for mobilization, and Newcastle Satisfaction with Nursing Care Scale (NSNCS) for satisfaction. Results: It was determined that the mean VAS score for pain decreased; the mean scores of PMS, OMS, and sub-dimensions decreased and the mobilization process was positively affected; the mean first walking distance increased; and the nursing care satisfaction increased more in the yoga nidra group compared to the control group (p
... More precisely, this practice, executed in supine position, naturally stimulates a hypnagogic state wherein an individual is physiologically asleep yet maintains an internal/external awareness (Sharpe et al., 2021); there is a withdraw from other senses, and only the auditory channel is open so that the participant stays aware of the directions coming from the instructor, but practices detachment from all other stimuli. YN interventions have been associated with significant improvements in sleep parameters such as sleep onset latency and sleep quality (Datta et al., 2017;Moszeik et al., 2020) because of a general parasympathetic dominance (Markil et al., 2012) and a subsequent high cardiac vagal control (Werner et al., 2015; see also YN Effects and Potential Benefits on Athletes); it first stimulates the parasympathetic nervous system increasing heart rate variability (HRV), or its high-frequency components (Markil et al., 2012), and alpha waves, to then demonstrate the symptoms of deep, non-REM sleep, including theta and delta brain waves (Parker et al., 2013). ...
... More precisely, this practice, executed in supine position, naturally stimulates a hypnagogic state wherein an individual is physiologically asleep yet maintains an internal/external awareness (Sharpe et al., 2021); there is a withdraw from other senses, and only the auditory channel is open so that the participant stays aware of the directions coming from the instructor, but practices detachment from all other stimuli. YN interventions have been associated with significant improvements in sleep parameters such as sleep onset latency and sleep quality (Datta et al., 2017;Moszeik et al., 2020) because of a general parasympathetic dominance (Markil et al., 2012) and a subsequent high cardiac vagal control (Werner et al., 2015; see also YN Effects and Potential Benefits on Athletes); it first stimulates the parasympathetic nervous system increasing heart rate variability (HRV), or its high-frequency components (Markil et al., 2012), and alpha waves, to then demonstrate the symptoms of deep, non-REM sleep, including theta and delta brain waves (Parker et al., 2013). ...
... This would allow to better examine neural correlates of a passive recovery strategy. From a cardiophysiological perspective, as most of the studies reveal that relaxation produces a transient effect on HRV and long-term relaxation studies are scarce, ECG data and ad hoc trials could be used to clarify the nature of changes in HRV, as well as the physiological mechanisms underlying the increase in HRV induced by YN (Markil et al., 2012). Findings, while providing clearer data concerning YN mechanisms, may further shed light on the effect of an aware sleep state on sleep quality and on the usefulness of this kind of yoga technique for improving recovery in athletes. ...
... 9 Yoga Nidra technique has been found produce favorable changes in HRV by shifting autonomic balance to its parasympathetic branch. 10 The number of reports on the effects of this technique on HRV is scanty. Hence, this study was conducted to analyze the immediate effects of Yoga Nidra relaxation on HRV of young and healthy volunteers and compare it with the effects of simple supine rest maneuver. ...
... These findings are in accordance with the study done by Markil et al 10 in Florida in which Yoga Nidra relaxation produced significant variations from baseline HRV values in university students. The HF increased whereas LF and LF:HF ratio decreased in the Yoga Nidra post-relaxation period. ...
... The HF increased whereas LF and LF:HF ratio decreased in the Yoga Nidra post-relaxation period. 10 The study showed that Yoga Nidra shifts the autonomic balance to the parasympathetic system as demonstrated by significant changes in the HRV indices. ...
Introduction: Cardiovascular autonomic functions are affected by the negative influences of stress which bring about alterations in heart rate variability (HRV). Yoga based relaxation techniques like Yoga Nidra have been found to relieve stress as shown by improved HRV. This study was conducted to assess the immediate effects of a yoga based guided relaxation technique, Yoga Nidra on HRV parameters in young and healthy volunteers. Methods: This was an interventional study conducted in the Department of Clinical Physiology, Institute of Medicine, Maharajgunj. Fifty two male medical students were divided into supine rest group (n=26) and Yoga Nidra group (n=26). HRV indices were recorded before and after supine rest and Yoga Nidra. Intra-group and inter-group comparisons of the HRV parameters were done before and after the interventions. Results: In comparison to the supine rest, Yoga Nidra produced significant increase in values of HF (1460.72 Vs 3272.99; p=0.03) and HFnu (50.32 Vs 62.68; p=0.004); and significant reduction in the values of LFnu (49.68 Vs 37.32; p=0.004) and LF:HF ratio (0.99 Vs 0.59; p=0.004), which suggested that the parasympathetic modulating response of Yoga Nidra was better than that of supine rest. Conclusion: Yoga Nidra, a yoga based relaxation technique brings better relaxation response than supine rest as indicated by the significantly improved HRV indices.
... The participants in the experimental group were instructed to do yoga nidra and encouraged to incorporate it into their normal yoga practice by practicing for 30 minutes per day (except Sunday and holidays) for a period of six months. The control group of students was given the assignment to do their usual yoga routine (asana, pranayama and shatkarmas) 43 . The study showed a significant change in the ESR level by the inclusion of yoga nidra practice. ...
... students compared to the findings of those who performed just the usual yoga regimen. These results concluded that yoga nidra could help relieve stress, balance metabolism, and enhance general bodily functioning 38,43 . (Table 1) This article aimed to enhance the long-term outcomes for children diagnosed with mental health disorders by describing the numerous risk factors for CVD in childhood and the various methods for mitigating these risks. ...
Ahara, nidra, and brahmacharya are the three fundamental pyramids of life according to the ancient Ayurvedic texts, and they all play an essential part in preserving human health. Nidra nourishes the body and helps us avoid sickness by reducing stress. When practised regularly, nidra may help a person to live a long and healthy life, retain their memory and intellect as they age, and improve their appearance, voice, and overall health. In addition to reversing disease processes and preventing recurrence, nidra may help boost a person's immune system so that he can avoid contracting illness. Anidra refers to the array of clinical states brought on by nidra deficiency (primary insomnia). Chronic insomnia, also known as secondary or tertiary insomnia, is a symptom of poor health that may lead to psychological difficulties such as dissociation from reality (delusions), paranoia, and hallucinations. There is an increased risk of cardiovascular illness in those with poor mental health because of its impact on the cardiovascular system. For both psychological and physical well-being, nidra is a valuable tool. This review presents a critical explanation of nidra, mental health, and their relationship with respect to cognitive and physiological aspects.
... A sample of 50 nursing students was randomly selected and data were collected using a modified stress assessment scale. The stress levels were categorized into five categories of "severe" (57-80), "high" (47-56), "moderate" (37)(38)(39)(40)(41)(42)(43)(44)(45)(46), "low" (27)(28)(29)(30)(31)(32)(33)(34)(35)(36), and "very low" (0-26). The investigators found that following 20 days of yoga nidra practice, the mean stress scores were significantly reduced (before yoga nidra, 28.82; after yoga nidra, 17.8 [p < 0.05]), thus supporting the conclusion that yoga nidra is a practical and easily applied stress prevention technique for students of demanding professions such as nursing [22]. ...
... The randomized study used a counter-balanced design with participants completing a relaxation-only (R) session and a yoga plus relaxation (YR) session. The current findings show that Yoga Nidra relaxation increases HRV, and that the responses are unaffected by a previous Hatha yoga session [36]. ...
Yoga nidra, also known as ‘yogic sleep’, is a simplified form of an ancient tantric relaxation technique. The most general description of the practice is that it combines guided mental imagery with a specific yoga posture called Shavasana (or “corpse pose”). The goal of yoga nidra is to promote a profound state of relaxation, which differs from sleep inasmuch as there is still an awareness of one’s surroundings. While several components of the practice have been known since ancient times, it was not until the nineteen-sixties that an updated and systematized system of practice was introduced to the public through the writings of Swami Satyananda Saraswati. Unlike other schools of yoga, which emphasize concentration or contemplation, yoga nidra’s goal is complete relaxation. As such, its advocates claim that it is suitable for all individuals, from beginners to advanced practitioners of yoga. The calm inner stillness induced by yoga nidra is claimed by practitioners to be an effective stress management tool as well as a means for attaining greater receptivity to personal resolutions. These resolutions can range from the goal of achieving self-transformation, enhancing creativity, or improving one’s learning ability. Additionally, yoga nidra is claimed to promote beneficial changes in physiological and mental health. The following narrative review summarizes the basic steps used to achieve the final state of yoga nidra relaxation as well as some recent experimental findings regarding its physiological and psychological effects. Standard research databases were searched for relevant articles. Clinical studies have shown that yoga nidra meditation is associated with positive physiological changes, including improvements in several hematological variables, red blood cell counts, blood glucose levels, and hormonal status. Two neuroimaging studies have shown that yoga nidra produces changes in endogenous dopamine release and cerebral blood flow, a further confirmation that its effects on the CNS are objectively measurable. The practice has also been shown to reduce psychometrically measured indices of mild depression and anxiety, although these benefits were not shown in an experimental study to extend to severe depression or severe anxiety.
... Markil N et al. [30] To compare acute sympathovagal changes as measured by HRV responses to yoga nidra relaxation alone compared to yoga nidra relaxation preceded by hatha yoga 15 Following bhastrika pranayamic breathing for 5 min both systolic and diastolic blood pressure decreased significantly, with a slight decrease in heart rate; The group of volunteers whose heart rate and BP were compared before and after breathing exercise following intake of hyoscine-N-butylbromide showed no significant alteration in either of these para-meters ...
... Three studies included only male participants, with the rationale for excluding females being the tendency in variation of the autonomic variables with the phases of the menstrual cycle in females. However, Markil et al.[30] included 15 women in their study, completing the study during the follicular phase of the menstrual cycle given that the luteal phase causes increase in sympathetic activity. One study didnot mention the sex of the participants. ...
... Several investigators have demonstrated the effects of stress and relaxation on HRV. Improvements in HRV measurements have been shown in autonomic balance during relaxation therapies and interventions [10,22,23], mindfulness interventions [24], and laparoscopic surgeries with robotic assistance [25]. HRV has also been shown to decrease with psychological stress [15,26], perceived high work stress in nurses [27], and stress in nursing students [28]. ...
... Significant postinduction hypnosis-associated physiologic changes (min[16][17][18][19][20][21][22]. ...
Background
Previous work performed by our group demonstrated that intermittent reductions in bispectral index (BIS) values were found during neurofeedback following mindfulness instructions. Hypnosis was induced to enhance reductions in BIS values.
Objective
This study aims to assess physiologic relaxation and explore its associations with BIS values using autonomic monitoring.
Methods
Each session consisted of reading a 4-minute baseline neutral script and playing an 18-minute hypnosis tape to 3 researchers involved in the BIS neurofeedback study. In addition to BIS monitoring, autonomic monitoring was performed, and this included measures of electromyography (EMG), skin temperature, skin conductance, respiratory rate, expired carbon dioxide, and heart rate variability. The resulting data were analyzed using two-tailed t tests, correlation analyses, and multivariate linear regression analyses.
ResultsWe found that hypnosis was associated with reductions in BIS (P
... Heart Rate (bpm) Decreases (s) by 8.55 % (Markil et al., 2012) Increases ( ...
... Increases (s) by 20.75 % between pre and post intervention of Yoga for a month(Vinay et al., 2016) for RRI. Hatha Yoga increases HF-power after yoga-nidra(Markil et al., 2012). ...
Different body postures that can be maintained for a certain duration with awareness are called yoga-asanas. These asanas matter flexibility, coordination, and strength, while the breathing practices and meditation sharpens the mind for better awareness and reduce anxiety and thus adds quality into life. Other beneficial effects might involve a reduction of stress, blood pressure, and improvements in resilience, mood, and metabolic regulation. The asanas performed regularly for a short duration in hours is well studied in the literature. However, when performed for a long duration continuously for several hours (40-hour yogathon), without food and sleep has a significant effect in regulating homeostasis. The homeostasis is accessed through cardio-respiratory and galvanic skin response changes. The study shows the physiological changes after the yogathon and compares it with effects on physiology due to short term yoga. It also emphasizes on the reduction of dependency on food, because of energy compensation through yoga-asanas.
... Therefore, MBIs might be able to fill a void in symptom control and management with CVD [11]. MBI may be done at home or an outside facility, with 1-3 weekly sessions done over 12 weeks [12]. ...
... HRV was shown to be higher and have a wide range in younger individuals and decreases with age. Some studies have noted increased HRV with meditation, yet consistency in the findings is lacking [12]. When assessing MBI utility, limitations exist regarding what intervention or practice participants undertake, and how that data can be accounted for in a study [17]. ...
Stress disrupts healthy cardiovascular function, influencing or triggering the development of cardiovascular disease (CVD) and disorders by elevating blood pressure (BP), increasing heart rate (HR), cortisol levels, and insulin resistance. The utilization of mind-fulness-based interventions (MBIs) has been associated with a reduction in specific symptoms, markers, and hallmarks of CVD. This meta-analysis reports on the beneficial effects of several of these mindfulness-based inventions on the cardiovascular system in response to stress and makes a case for further research on such.
... 30,31 Increasing parasympathic activity and decreasing sympathetic activation is regarded as a primary mechanism of yoga therapy. 30,32 Specifically, yoga breathing and relaxation exercises have been shown to increase parasympathetic activity both in healthy individuals 33,34 and in patients with chronic obstructive pulmonary disease. 35,36 Importantly, the addition of yoga postures does not further increase this effect, 33 meaning patients with reduced physical capacity may gain benefit from yoga through the practice of yogabased breathing techniques alone. ...
... 30,32 Specifically, yoga breathing and relaxation exercises have been shown to increase parasympathetic activity both in healthy individuals 33,34 and in patients with chronic obstructive pulmonary disease. 35,36 Importantly, the addition of yoga postures does not further increase this effect, 33 meaning patients with reduced physical capacity may gain benefit from yoga through the practice of yogabased breathing techniques alone. Our results also support the role of breathing in chronic conditions with similar sympathetic activation, such as cardiovascular conditions. ...
Objectives
To determine the effectiveness and safety of yoga interventions on disease symptoms, quality of life and function in patients diagnosed with chronic obstructive pulmonary disease (COPD).
Data sources
Medline/PubMed, Scopus, and CENTRAL (Cochrane Central Register of Controlled Trials) were searched through 6 June 2019.
Review methods
Randomized controlled trials assessing the effects of yoga on quality of life, dyspnea, exercise capacity, and pulmonary function (FEV1) in patients with COPD were included. Safety was defined as secondary outcome. Mean differences (MD) and standardized mean differences (SMD) with 95% confidence intervals (CIs) were computed. Risk of bias was assessed using the Cochrane tool.
Results
Eleven randomized controlled trials with a total of 586 patients were included. Meta-analysis revealed evidence for effects of yoga compared to no treatment on quality of life on the COPD Assessment Test (MD = 3.81; 95% CI = 0.97 to 6.65; P = 0.009, I² = 70%), exercise capacity assessed by the 6-minute walk test (MD = 25.53 m; 95% CI = 12.16 m to 38.90 m; P = 0.001, I² = 0%), and pulmonary function assessed by FEV1 predicted (MD = 3.95%; 95% CI = 2.74% to 5.17%; P < 0.001, I² = 0%). Only the effects on exercise capacity and pulmonary function were robust against methodological bias. Effects were only present in breathing-focused yoga interventions but not in interventions including yoga postures. Adverse events were reported infrequently.
Conclusion
This meta-analysis found robust effects of yoga on exercise capacity and pulmonary function in patients with COPD. Yoga, specifically yoga breathing techniques, can be an effective adjunct intervention for patients with COPD. Yoga’s safety needs to be assessed in more depth in future studies.
... [27][28][29] Studies have found that the Yoga Nidra practice (or "state") appears to reflect an integrated response by the hypothalamus, resulting in decreased sympathetic (excitation) nervous activity and increased parasympathetic (relaxation) function. [30] Results show that there was a significant improvement in positive well-being, general health, and vitality in the Yoga Nidra group. The association of Yoga Nidra with a shift toward parasympathetic dominance [30] is also related to high cardiac vagal control, which, in turn, is related to reduced anxiety and better subjective and objective sleep quality. ...
... [30] Results show that there was a significant improvement in positive well-being, general health, and vitality in the Yoga Nidra group. The association of Yoga Nidra with a shift toward parasympathetic dominance [30] is also related to high cardiac vagal control, which, in turn, is related to reduced anxiety and better subjective and objective sleep quality. [31] In a study on the effects of Yoga Nidra over sleep, the morning practice has been found to increase parasympathetic drive at night causing sleep to be more restorative, which may explain significant improvement in sleep-quality ratings. ...
Background: World statistics for the prevalence of anxiety and mood disorders shows that a great number of individuals will experience some type of anxiety or mood disorder at some point in their lifetime. Mind–body interventions such as Hatha Yoga and seated meditation have been used as a form of self‑help therapy and it is especially useful for challenging occupations such as teachers and professors. Aims: In this investigation, we aimed at observing the impact of Yoga Nidra and seated meditation on the anxiety and depression levels of college professors. Materials and Methods: Sixty college professors, men and women, aged between 30 and 55 years were randomly allocated in one of the three experimental groups: Yoga Nidra, seated meditation, and control group. Professors were evaluated two times throughout the 3‑month study period. Psychological variables included anxiety, stress, and depression. Results: Data analysis showed that the relaxation group presented better intragroup results in the anxiety levels. Meditation group presented better intragroup results only in the anxiety variable (physical component). Intergroup analysis showed that, except for the depression levels, both intervention groups presented better results than the control group in all other variables. Conclusions: Prepost results indicate that both interventions represent an effective therapeutic approach in reducing anxiety and stress levels. However, there was a tendency toward a greater effectiveness of the Yoga Nidra intervention regarding anxiety, which might represent an effective tool in reducing both cognitive and physiological symptoms of anxiety
... A simultaneous increase in parasympathetic activity and decrease in sympathetic activity has been postulated as an important mechanism of action of therapeutic yoga (22). In this context, particularly yoga techniques of slow breathing and meditation may bring about a short-term reinforcement of parasympathetic activity (23)(24)(25). In experimental studies where yoga relaxation techniques were supplemented with yoga postures, no further potentiation of parasympathetic activity ensued (23). ...
... In this context, particularly yoga techniques of slow breathing and meditation may bring about a short-term reinforcement of parasympathetic activity (23)(24)(25). In experimental studies where yoga relaxation techniques were supplemented with yoga postures, no further potentiation of parasympathetic activity ensued (23). Together with the findings of the meta-analysis (11), this led to breathing and meditation techniques, rather than yoga postures, being viewed as the principal mechanism of action of yoga in patients with arterial hypertension (26). ...
Background:
Yoga seems to exert its effect against arterial hypertension mainly through the associated breathing and meditation techniques, and less so through yoga postures. The goal of this trial was to compare the blood pressure-lowering effect of yoga interventions with and without yoga postures in patients with arterial hypertension.
Methods:
75 patients taking medications for arterial hypertension (72% women, mean age 58.7 ± 9.5 years) were randomized into three groups: a yoga intervention group with yoga postures (25 patients, of whom 5 dropped out of the trial before its end), a yoga intervention group without yoga postures (25 patients, 3 dropouts), and a wait list control group (25 patients, one dropout). The interventions consisted of 90 minutes of yoga practice per week for twelve weeks. The data collectors, who were blinded to the intervention received, assessed the primary outcome measures "systolic 24-hour blood pressure" and "diastolic 24-hour blood pressure" before and after the intervention. In this report, we also present the findings on secondary outcome measures, including follow-up data.
Results:
After the intervention, the systolic 24-hour blood pressure in the yoga intervention group without yoga postures was significantly lower than in the control group (group difference [Δ]= -3.8 mmHg; [95% confidence interval (CI): (-0.3; -7.4) p = 0.035]); it was also significantly lower than in the yoga intervention group with yoga postures (Δ = -3.2 mmHg; 95% CI: [-6.3; -0.8]; p = 0.045). Diastolic blood pressures did not differ significantly across groups. No serious adverse events were encountered in the course of the trial.
Conclusion:
In accordance with the findings of earlier studies, we found that only yoga without yoga postures induced a short-term lowering of ambulatory systolic blood pressure. Yoga is safe and effective in patients taking medications for arterial hypertension and thus can be recommended as an additional treatment option for persons in this category.
... We show here that Hindu traditions were able to identify subtle subjective (but ultimately neurological in origin) relationships between various sensory and cognitive systems. These subtle neurological relationships are based upon evolutionary and developmental biology-the burgeoning evidence that meditative, Yogic and breathing practices based on Indic traditions can lead to drastic reshaping of the nervous system, sometimes even allowing advanced practitioners volitional control over processes otherwise thought to be autonomous, provide evidence to the external validity of this schema, as well as its universality (Benson et al., 1974;Kozhevnikov et al., 2013;Lazar et al., 2000;Markil et al., 2012;Pal et al., 2014;Raghavendra et al., 2013;Travis & Arenander, 2006;Venkatraman et al., 2019;Wenger et al., ...
Information from our senses, memories and thoughts is bound together into a unified whole that constitutes our experience of our world, our Umwelt. However, our ability to investigate our Umwelt through standard Western-derived neuroscience is limited, because of the third-person approach that undergirds the field. Achieving greater coherence in our understanding requires the addition of an approach which is fundamentally integrative. The most comprehensive first-person approach to the nervous system can be found in the introspective traditions of Tantric Hinduism. In this review, we explore the hierarchical ordering of the senses in Hinduism (from most gross to the most subtle, the latter being closer to consciousness), and how this may be linked to sensorimotor coupling in the parietal cortex. We demonstrate how this ordering parallels the developmental history of the sensory cortices over the course of vertebrate evolution. The synergy between biosemiotics and neurophenomenology is made clear, as the idea of a “Great Chain of Semiosis” can be very helpful in understanding the reasons behind the emergence of this sensory hierarchy. The structures of the Subtle body described in Hindu Tantra should be seen as semiotic nodes used by the conscious agent in interacting with the world around it. We propose that metaphor ties together the various sensory mappings of the body at the cognitive level. Integrating insights from Hindu Tantra will help modern science better investigate questions of agency, meaning and semiosis in organisms.
... [12] Markil N emphasized increase in heart rate variability during Yoga Nidra Relaxation. [13] Yoga is being promoted as a path for a healthy lifestyle to improve quality of life. Though there are research studies assessing the long-term benefits of yoga/ meditation on autonomic functions, we substantially lack knowledge about the immediate sequential changes that ensue during the process which results in desired effects. ...
Introduction: Yoga being promoted as a path for a healthy lifestyle to improve quality of life, is found to have beneficial effects in individuals practicing yoga, they reap the long-term benefits of practice in the form of reduced stress levels, well equipped coping mechanism, nature of calm and composed, enhanced cognitive abilities by affecting the autonomic function. Considering this we were interested in exploring the immediate effect of yogic techniques on autonomic function, so we intended to study the immediate changes in autonomic function test in the form of Heart Rate Variability (HRV) due to Isha Kriya Meditation (IKM). Materials and Methods: Continuous HRV recording for 45 minutes was done in volunteers between the age of 20-40 years, The recording was segregated into 3 phases of 15 minutes each including Pre-IKM, During IKM and Post IKM respectively. HRV analysis was done, data was compiled in excel sheet and statistical analysis was done using Jamovi to compare the changes in HRV parameters induced by IKM. Results: 42 volunteers willing to practice IKM were included with an average age of 23 ± 1.2 years. There was an increase in time domain parameter SDNN and the frequency domain parameter the power of LF which was significant with confidence interval of 95% and p value of 0.03 immediately after the practice of isha kriya. Conclusion: Practice of IKM sequentially tilts the autonomic balance towards sympathetic predominance, providing better attention and mental clarity.
... [42], [44], [45], [47]. HFnu has been reported to correlate with the level of perceived relaxation [49], [50], and is inversely associated with perceived stress, arousal and anxiety [51], [52]. Therefore, HFnu was adopted as the physiological parameter linked to the feedback in the HRV-based VR-BF session [53]. ...
Anxiety symptoms are important contributors to the global health-related burden. Low-intensity interventions have been proposed to reduce anxiety symptoms in the population. Among these, biofeedback (BF) offers an effective approach to reducing anxiety. In the present study, BF was integrated into a novel virtual reality (VR) architecture to enhance BF's effectiveness to i) evaluate the feasibility of a VR-based single-session BF in teaching participants to self-regulate; ii) compare the BF aiming at reducing sympathetic (measured though the tonic level of skin conductance, SCL) versus increasing cardiac vagal (i.e., normalized high frequency of heart rate variability, HFnu-HRV) activation, and iii) evaluate which of the two VR-BF single-sessions was most effective in reducing perceived state anxiety. 20 healthy participants underwent both SCL- and HFnu-based in a single session VR-BF. Results showed the feasibility of a short single-session VR-BF and the effectiveness of both VR-BF sessions in reducing perceived state anxiety. Moreover, SCL-based VR-BF determined a significant reduction in sympathetic activation and in sympathovagal balance as well as a greater reduction in perceived state anxiety compared to HFnu-based VR-BF. SCL-based VR-BF represents a safe and effective intervention in reducing anxiety while enhancing adaptive psychophysiological activation.
... Studies that observed increases in HRV measures following single yoga sessions typically focused on meditative practice or slow breathing. 38,53,54 One recent study of an acute Hatha yoga practice observed significant increase in HRV from baseline in the time-domain SDNN, but the control condition similarly increased from baseline and these measures were taken during practice (in the last 5 minutes of the intervention). 55 In contrast, we observed a decrease in time domain outcomes (SDNN, SDRR, RMSSD) following yoga, but we similarly observed increased HRV measures in our control condition. ...
Objective: Test anxiety is common among nursing students. Yoga is one form of physical activity which may be beneficial for pretest anxiety. Participants: Thirteen undergraduate students (85% nursing majors, 15% awaiting program entry, 20 ± 4.9 years of age) completed the crossover design study. Methods: Participants completed a yoga or control intervention (independent quiet study) on opposing testing days. At three time points, participants provided ratings of anxiety (visual analog scales), saliva samples for cortisol and alpha amylase, and seated heart rate variability (HRV, time and frequency domains) was recorded. Results: Yoga prior to a simulated exam had a positive impact on subjective measures of stress but did not positively impact cortisol or HRV compared to the control condition. Conclusions: There may be benefits to participating in 30 min of moderate intensity yoga for reduced perception of stress before a scholarly examination. Further research regarding the impacts of acute yoga on physiological measures of HRV and/or cortisol are warranted.
... u. and increased HFn. u. 24,25 A recent study reported increase in both frequency and time domains 8 whereas another study of coronary heart disease patients reported a marginal increase in absolute power of HF-HRV after 16 weeks of meditation compared to control group that received health education. ...
Background & Objectives Yoga and meditation is now widely accepted world wide as an effective tool to combat stress. Heart Rate Variability (HRV) is a noninvasive tool to measure sympathetic and parasympathetic function of the autonomic nervous system. Yoga, by modulating stress, has shown to decrease the activity of sympathetic component of autonomic nervous system and enhance parasympathetic component. Only few studies have compared HRV at baseline with HRV during or after single session of yoga. Thus, this study was undertaken with the objectives to compare HRV changes of Sahaja Yoga Meditators in resting state with their Meditation state and to compare these changes with HRV changes in the control group in resting and meditation mimicking state. Method A prospective randomized controlled study was conducted. The study group comprised of 30 randomly selected long term Sahaja yoga mediators and a control group of 30 subjects with no prior practice of any kind of meditation. HRV was recorded in both the groups in normal resting state, during meditation (yoga group) and with eyes closed (mimicking meditation in control group). Results Study showed decrease in LF (sympathetic activity) increase in HF (parasympathetic activity) and decrease in LF/HF ratio thus implying a more relaxed, parasympathetic dominant state, in the yoga group during meditation. Conclusion The study shows Sahaja Yoga meditation leads to a parasympathetic dominant (relaxed) state and thus can be used as an effective mind body technique to combat stress.
... Sankalpa and cognitive restructuring processes can prevent or counteract dysfunctional cognitions, thereby inducing life satisfaction and individual well-being [20]. Moreover, due to a general parasympathetic dominance [21] and a subsequent high cardiac vagal control [22], YN interventions can significantly improve subjective and objective sleep quality [16,23]. Indeed, it is frequently suggested in sleep lab protocols [19], also because 1 h of YN can be as restorative and rejuvenating as 4 h of ordinary sleep [17]. ...
Yoga Nidra (YN) naturally stimulates a hypnagogic state wherein an individual is physiologically asleep yet maintains a certain awareness to follow a guide's instructions. The aim of this study was to investigate the effects of this aware sleep state on recovery-stress balance in two elite karate athletes adopting an idiosyncratic and multimodal approach. One male and one female athlete underwent a YN intervention. Before intervention, after intervention and three weeks later, recovery-stress balance specific scales, perceived stress, cognitive and somatic anxiety, subjective and objective sleep quality, and individual alpha peak frequency (iAPF) values were assessed. Perceived quality of recovery was continuously monitored for three months including the period of the investigation. Feelings and arousal levels before and after each YN session were also examined. Our results showed a YN general positive effect; however, the intervention had higher sport specific effects in the male compared to the female athlete. On the other hand, in the female athlete, YN seems to have effects both from an emotional and physical point of view. We also noted the intertwined relationship among interoception, perceived stress and YN effects. Also, findings suggest that iAPF modulation reflected improved recovery skills or a better control of stressful situations, while the acute effects on arousal levels were expression of anxiety or energy reduction. Overall, YN improved both the perceived quality of recovery and sleep quality, shedding light on the importance of YN for recovery-stress balance enhancement in the sport context.
... 7 Two neuro-imaging studies have shown that Yoga Nidra produces changes in endogenous dopamine release and cerebral blood flow. 8 The current findings show that Yoga Nidra relaxation increases HRV, and that the responses are unaffected by a previous Hatha yoga session. 9 Control of fluctuating blood glucose In T2DM patients when Yoga Nidra practice was combined with oral hypoglycemic medications. ...
When awareness is separate and distinct from mental activity, When waking, dream and deep sleep pass like clouds, Yet awareness of Self remains, This is the experience of total relaxation…That is why, in tantra, Yoga Nidra is said to be the doorway to Samadhi.1”- Swami Satyananda
... While these mechanisms help the body to cope with immediate threat (González-Díaz, Arias-Cruz, Elizondo-Villarreal, & Monge-Ortega, 2017), chronic exposure to stress may lead to dysregulation of multiple systems resulting in poor sleep (Alotaibi, Alosaimi, Alajlan, & Bin Abdulrahman, 2020), somatic symptoms (Glise, Ahlborg, & Jonsdottir, 2014) and depression and anxiety (Davis, Holmes, Pietrzak, & Esterlis, 2017). Several studies suggested the benefits of yoga nidra in stress-related implications through neurophysiological changes such as: an increase in heart rate variability (Markil, Whitehurst, Jacobs, & Zoeller, 2012); decrease in respiratory rate (Sharpe et al., 2023), decrease in blood pressure (Devraj et al., 2021;Manik & Gartia, 2016), which can be indicative of autonomic balance and parasympathetic response following yoga nidra relaxation. While almost all included studies in this review used behavior outcomes, overall collective available evidence suggests the effectiveness of yoga nidra in addressing the psychological and physiological implications of stress. ...
The provision of mental health care is currently inadequate worldwide. A need for innovative, accessible, and evidence-based mental health interventions has been identified. This study explored the potential use of yoga nidra practice as mental health intervention through reviewing current relevant evidence. Sixteen studies were examined, revealing the effectiveness of yoga nidra in stress, depression, and anxiety. Though evidence was limited, yoga nidra also seemed to be effective in posttraumatic stress disorder and psychological well-being. In view of the findings, yoga nidra may warrant consideration as a preventive and therapeutic mental health strategy. Implications for clinical practice and recommendations for future research are discussed.
... The randomized study used a counter-balanced design with participants completing a relaxation-only (R) session and a yoga plus relaxation (YR) session. The current findings show that Yoga Nidra relaxation increases HRV, and that the responses are unaffected by a previous Hatha yoga session (Markil et al., 2012). ...
... In fact, yoga nidra practice might have decreased sympathetic nervous activity and increased parasympathetic function. The shift towards parasympathetic dominance is related to high cardiac vagal control, and alterations in neurotransmitters which in turn, reduces anxiety, stress and improves mental well-being (Markil et al., 2012;Werner et al., 2015). Considering the nature of yoga nidra practice the results appeared so far are logically plausible. ...
Personality is a dynamic organization of psychophysical systems of an individual which determine a unique adjustment to one's environment. If the act of personality development is not proper in early years of life, an individual becomes the victim of behaviour disorders and reflects many identity crises in later life.
... Research on yoga-nidra is still in its evolutionary phase, however, studies to date suggest its efficacy in coping with depression, anxiety and insomnia (11)(12)(13)(14). It's been shown to increase alpha brain wave activity (15), Heart Rate Variability (HRV) (16), and Dopamine secretions (17), all three of which are considered strong measures of the body's stress accommodation response. HRV directly and accurately depicts the health status of an individual's autonomic nervous system (ANS). ...
Post COVID-19 patients tend to suffer from ongoing or new symptoms like shortness of breath, fatigue, lack of mental clarity etc. In some severe cases, these might lead to pulmonary fibrosis and need persistent oxygen requirement. Yoga & meditation interventions have been used as an effective adjunct to chronic respiratory diseases in the past. However, this case presents the use of 20 minutes yoga-nidra sessions to cope-up with persistent low-flow oxygen requirement, tachycardia in a 23-year-old male subject over the course of 9 days. This case shows that regular practice of yoga-nidra, without any breath-work and/or bodily postures, might help aid rehabilitation of post-COVID patients and those with severe pulmonary complications when given as a complementary therapy, especially among those unable to do asana or pranayama due to lack of strength, old-age or any other medical reasons. Future pilot studies are necessitated to create further new evidence. It also brings to light the vast untapped potential of mHealth aided Online yoga-based interventions that may spearhead future research in this domain of knowledge, especially during situations like the COVID pandemic.
... The positive effect of Yoga Nidra has been attributed to increased parasympathetic dominance and improvement in executive attention. [13,14] Mandlik et al. (2002) studied the effect of Yoga Nidra on EEG waves and found prominence of alpha waves and intermittent theta waves indicating deep relaxation. [15] However, more evidence needs to be gathered to establish the cause of improvement in cognition. ...
Background: Yoga Nidra is an ancient meditative relaxation technique known to relieve stress. Its impact on reaction time has not been studied. Aim and Objective: The aim of our study was to study the effect of Yoga Nidra on visual reaction time. Materials and Methods: Visual reaction time simple reaction time (SRT) choice reaction time (CRT) using Deary Liewald software was recorded in 44 medical students aged 18–21 years, before and after practicing Yoga Nidra for 20 min. The results were compared with regard to change in the mean values of SRT, CRT, and mean central processing time (MCPT) (CRT-SRT). Statistical analysis was done using unpaired t-test and statistical significance (P < 0.05) was calculated. Results: We found statistically significant change in the visual reaction time, in all the parameters, that is, SRT, CRT, and MCPT after subjecting the students to Yoga Nidra. Conclusion: Yoga Nidra significantly affects visual reaction time indicating the beneficial effect of this technique on cognition.
... The prefrontal cortex, cerebellum, and sub cortex, which control activities, all have lower blood flow, which is related to the reduced urge for activity in the condition (Kjaer, Bertelsen, Piccini, Brooks, Alving, & Lou, 2002) [9] . In accordance with another study, yoga nidra, whether or not it is preceded by a session of hatha yoga asanas, increases heart rate variability, a gauge of the autonomic nervous system's balance (Markil, Whitehurst, Jacobs, & Zoeller, 2012) [11] . ...
Yoga nidra is the state of yoga in which one is able to control his own emotions and efforts while in sleeping. The objective of present study is to revealing the benefits of yoga nidra for mental stress. Balanced biological state, psychological and social factors which may be able to control mental ability and environment termed as mental health. Yoga nidra is profound as the meditative state of Samadhi. Yoga nidra is the way to stand up to all the life problems and still lead a stress-free life. It has immense benefits, which helps us to organize our inner thoughts and stay focused on solving issues with a positive attitude.
... 11,12 Because of some studies' findings, the combination of relaxation strategies and Hatha yoga has shifted in autonomic balance along the continuum from the sympathetic to the parasympathetic branch of the ANS. 13,14 To that end, researchers have argued that yoga may promote parasympathetic activation that leads to reduced HR and BP and improved HRV, together with other metabolic and psychological benefits, including decreased levels of depression, 15 improved quality and quantity of sleep, 16 decreased risk for metabolic syndrome, 17 and weight reduction in the form of decreased visceral fat. 18,19 The purpose of the current study was to delineate the immediate cardiovascular effects of 12 Hatha yoga poses by means of RR and JT intervals. ...
... However, very few studies examined the effects of yoga on cardiovascular reactivity. Markil et al. (2012) reported a significant reduction in heart rate after an acute bout of Yoga Nidra relaxation. Since no mental challenge was administered in this study, whether the practice of this yoga technique could dampen cardiovascular responses to mental stress remains unknown. ...
Yoga has been shown to reduce stress and to provide health benefits for a number of stress-related disorders. However, the effects and mechanism of an acute bout of yoga practice on relieving stress remain unclear. The aim of this study was to examine the effect of a single bout of yoga on heart rate (HR) and heart rate variability (HRV) response to and recovery from mental stress. This study was conducted with a randomised, counterbalanced, crossover design. A total of 44 participants (mean age 24.58 ± 3.84) completed two conditions (yoga and video watching (VW)) in a randomly assigned order. After each condition, participants underwent a Stroop task and mental arithmetic task. HR and HRV, measured via electrocardiogram, were recorded and analyzed at rest, during each condition, and during the stress and recovery periods. HR was significantly lower during the yoga condition as compared to that during the VW condition. There was no significant difference in HRV observed between the conditions. During both mental stress and recovery periods, there was no significant difference in HR or HRV responses between the yoga and VW conditions. These findings suggested that an acute bout of yoga practice was not superior to quiet sitting in reducing HR and HRV reactivity to and recovery from mental stress. Future studies may consider investigating individuals with exaggerated cardiovascular reactivity to further examine the potential reactivity-lowering effect of yoga.
... In this sense, the results are diverse. There are studies [77][78][79] where the indicators of good regulation were greater with this type of intervention while, as in our study, no significant differences were found in others [80,81]. ...
The continuous changes in our society require adapted training that encompasses both technical and competency knowledge. There is a high level of demand, especially in areas such as engineering, which can affect the mental health of students, producing high levels of stress and psychological distress, hindering self-efficacy and academic performance. Embodied learning working on self-awareness, stress reduction and self-knowledge can help to generate healthier environments. Creative therapies can be a tool to promote the prevention of health problems in this group of the population. In particular, Dance Movement Therapy has demonstrated its effectiveness in improving health in clinical and non-clinical settings. In this work, a body awareness program based on Dance Movement Therapy is developed and implemented in engineering students. Through a mixed pre-post methodology, its impact is evaluated and analyzed in an experimental group of engineering students. Psychometric tests, physiological variables and reflective diaries are used as data sources. The results show that the experimental group, compared with the control group, increased their levels of body awareness and connectedness, well-being and life satisfaction and reduced their stress levels. The results were supported by cortisol measures. Likewise, the students acknowledged having increased their levels of self-awareness and self-knowledge and considered the inclusion of these bodily approaches in higher education to be necessary.
... As a percentage of TIB, SWS showed a moderate effect in PSG parameters. Yoga nidra has been found to be associated with a shift towards parasympathetic dominance, 28 and high cardiac vagal control is related to better subjective and objective sleep quality. 29 Yoga practice in the morning has been found to increase parasympathetic drive at night, 30 causing sleep to be more restorative. ...
Background
Yoga nidra is practised by sages for sleep. The practice is simple to use and has been clearly laid out, but its role in the treatment of chronic insomnia has not been well studied.
Methods
In this randomized parallel-design study conducted during 2012–16, we enrolled 41 patients with chronic insomnia to receive conventional intervention of cognitive behavioural therapy for insomnia ( n =20) or yoga nidra ( n =21). Outcome measures were both subjective using a sleep diary and objective using polysomnography (PSG). Salivary cortisol levels were also measured. PSG was done before the intervention in all patients and repeated only in those who volunteered for the same.
Results
Both interventions showed an improvement in subjective total sleep time (TST), sleep efficiency, wake after sleep onset, reduction in total wake duration and enhancement in subjective sleep quality. Objectively, both the interventions improved TST and total wake duration and increased N1% of TST. Yoga nidra showed marked improvement in N2% and N3% in TST. Salivary cortisol reduced statistically significantly after yoga nidra (p=0.041).
Conclusion
Improvement of N3 sleep, total wake duration and subjective sleep quality occurred following yoga nidra practice. Yoga nidra practice can be used for treatment of chronic insomnia after supervised practice sessions.
... [26] It has been demonstrated that Yoga-nidra produces a favorable shift in autonomic balance to the parasympathetic branch of the autonomic nervous system. [27] Reduced sympathetic activity leads to enhanced physical and mental relaxation. ...
Introduction: Educational interventions aimed at enhancing well-being are the need of the hour. Yoganidra has potential to enhance well-being through release of stress on physical, emotional and mental planes of consciousness through creation of an experiential state of deep relaxation through an inner awareness with simultaneous detachment. The study was done to analyze the effects of Yoganidra on various dimensions of well-being amongst trainee teachers.
Methodology: Trainee teachers participated in Yoganidra sessions over three months. Various aspects of well-being studied were 1) Perceived stress (using Visual Analogue Scale and Perceived Stress Scale), 2) Happiness (using Faces scale), 3) Overall quality of life (using Cantril’s self-anchoring ladder) and 4) Psychological general well-being (using Psychological General Well Being Index-Short). An investigator designed tool was used additionally to capture certain deeper qualities of well-being hitherto not overtly measured in standard tools employed.
Results: Seventy-seven trainee teachers participated in the sessions over three months. Significant reduction in perceived stress scale score (p=0.005) along with improvement in happiness (p=0.0004), overall quality of life (p=0.039) and psychological general well-being (p=0.0003) was observed. There was statistically significant improvement in the qualities of enthusiasm (p=0.04), quietude (p=0.0008), mental stability (p=0.004), happiness (p=0.02) and feeling inspired (p=0.03).
Conclusion: Yoganidra practice brings about reduction in perceived stress, while enhancing emotional and cognitive dimensions of well-being such as happiness, psychological general well-being, overall quality of life, enthusiasm, quietude and stability. It can be considered as a useful tool for enhancing well-being.
... Among different indices of the parasympathetic nervous system, beat to beat variability in heart rate, hereafter referred to as heart rate Acronymns: HRV, heart rate variability; PNS, parasympathetic nervous system; HF-HRV, high frequency heart rate variability; RMSSD, root mean square of successive differences between R-R intervals; SDNN, standard deviation of heart beat N-N intervals;; b/m, breaths per minute.. ☆ This work was performed at the Helfgott Research Institute, at the National University of Natural Medicine, Portland, OR variability (HRV), has attracted much systematic investigation [7,[9][10][11][12][13][14]. For example, several studies have provided evidence that breathing techniques, [15][16][17][18] yoga, [15] tai chi, [19] meditation, [20] and other mind-body practices [21] impact HRV. Specifically, most evidence of breathing and meditation practices have measured acute HRV change (pre/post or during a single practice [15,16], or pre/post the intervention period (weeks or months) [17,19]. ...
Objective
Traditional Indian breath control practices of Pranayama have been shown to increase indices of heart rate variability (HRV) that are generally held to reflect parasympathetic nervous system (PNS) tone. To our knowledge, individual components of pranayama have not been separately evaluated for impact on HRV. The objective of this study was to isolate five components of a pranayama practice and evaluate their impact on HRV.
Methods
In a crossover clinical trial, 46 healthy adults were allocated to complete five activities in random order, over five separate visits: 1) sitting quietly; 2) self-paced deep breathing; 3) externally-paced deep breathing; 4) self-paced Sheetali/Sheetkari pranayama; and 5) externally paced Sheetali/Sheetkari pranayama
Results
Our final sample included 25 participants. There was a significant increase in a time-domain index of HRV, the root mean square successive differences between RR intervals (RMSSD), during the five interventions. The change in logRMSSD ranged from 0.2 to 0.5 (p < .01 in all conditions by paired t-test). Greater increases were evident during externally-paced breathing than during self-paced breathing (mean pre-during logRMSSD change of 0.50 vs. 0.36, p = .02) or sitting quietly (mean, 0.17 ms; p = .005 and 0.02 when comparing Activities 3 and 5 to Activity 1 by random intercept model with Tukey correction for multiple comparisons). Lastly, pre-during increase in RMSSD was greater for Sheetali/Sheetkari vs. deep breathing, when controlling for respiration rate, though not significantly different (p = .07 in random intercept model)
Conclusions
RMSSD increased with paced breathing, deep breathing, and Sheetali/Sheetkari pranayama, reinforcing evidence of a physiologic mechanism of pranayama.
Trial registration
NCT03280589
https://www.clinicaltrials.gov/ct2/show/NCT03280589?term=sheetali&draw=2&rank=1
... In one of them, authors compared 20 minutes of meditation (dhyana) with randomly thinking, meditative and non-meditative focusing, and found that meditation increased parasympathetic activity significantly with an increase in HF, NN50, pNN50, and a decrease in LF [45]. Markil et al. [46] investigated the effects of 30-minute yoga nidra relaxation alone and after 60 minutes of a HY session, and observed some positive changes in HRV parameters in both conditions. The HY session was very similar to the one performed in the current study. ...
Introduction. This study purposed to examine energy expenditure (EE) of one-hour hatha yoga (HY) practice and to compare changes in heart rate variability (HRV) during and right after HY practice.
Material and methods . A total of ten experienced female HY practitioners participated in the study voluntarily. Daily EE on a weekday and during a one-hour HY session was measured using a metabolic holter. The ECG holter was applied to record HRV variables 5 minutes before, during, 5 minutes after and 10 minutes after the one-hour HY session. The HY session included HY asanas for the first 55 minutes and meditation during the last 5 minutes.
Results. Participants showed 2201.40 kcal of total EE, and 421.70 kcal of active EE during the weekday. Active EE was 109.70 kcal (26% of daily active EE) during the one-hour HY session, and the mean MET was recorded as 2.57. HRV measurements showed crucial changes. Increased sympathetic activity observed in SDNN, RMSSD, NN50, pNN50, LF/HF, and HF did not reach the initial level after 15 minutes of total recovery time.
Conclusions. One hour of HY practice provided moderate EE. Moreover, 10 minutes of supine rest in addition to 5 minutes of the meditation phase of HY practice is not seen as completely effective in improving parasympathetic activity and returning the practitioners to their initial level. Extending the meditation phase at the end of the HY session by more than 10 minutes and measuring the recovery process of HRV could add more detailed results to the literature.
... Furthermore, Bowman et al. conducted a 90-minute yoga program twice a week for 6 weeks to elderly males and females, and noted a significant increase in the α-index of the parasympathetic nervous system after the yoga program 21) . Markil et al. instructed 20 males/females to follow a hatayoga program and reported that parasympathetic activity significantly increased after yoga 22) . Yoga may suppress the aging-related reduction in the ANS, especially the parasympathetic nervous system. ...
The autonomic nervous system (ANS) maintains homeostasis through the balance of the sympathetic and parasympathetic subsystems or divisions. Currently, analysis of heart rate variability (HRV) offers an indirect, non-invasive assessment of ANS function. An irregular lifestyle and stress are known to affect ANS balance, influencing many diseases. Moreover, ANS disorder plays an important role in climacteric symptoms in menopausal females. The purpose of this study was designed to assess the effects of yoga practice sessions (herein referred to as “yoga”) on ANS function and focused on the relationship between ANS function and subject age or personal history of yoga. A total of 113 healthy females participated in this study. They attended a 90-120 minute yoga practice session conducted by a well-qualified instructor. ANS function was assessed before and after the yoga practice session by HRV power spectral analysis. As a result, in females, yoga reduced fatigue by primarily improving sympathetic activity. In addition, the LnHF values tended to be increased after yoga only in the over-60y (60 years) group. Furthermore, there were individual differences in the amount of change in the sympathetic and parasympathetic activity values. In females with a low activity level before yoga, values were increased; whereas values decreased in females with a high activity value before yoga. In subjects with ≥5-year history of yoga, there was no significant correlation between the ANS parameters and subject age. Our study suggests that yoga for females supports well-balanced ANS function, and that the continuation of yoga over a period of time contributes to an improvement in ANS function.
... Часть техник не задействует конкретные рефлекторные дуги, но, тем не менее, тоже опосредованно влияет на тонус ВНС. К примеру, при активации ПСНС мышечный тонус снижается; если же сознательно расслабляем скелетную мускулатуру, это будет способствовать преобладанию парасимпатического тонуса: исследования показывают, что йога-нидра (техника расслабления), выполняемая как часть занятий хатхайогой, либо как изолированная техника, в обоих случаях приводит к изменениям ВСР, свидетельствующим о повышении парасимпатического тонуса [52]. При активации симпатического отдела дыхание учащается; если будем сознательно учащать дыхание -это активирует ВНС в сторону СНС. ...
The article is devoted to the influence of sympathetic nervous system (SNS) on the cardiovascular system. Influence of SNS activity on the blood pressure level and the pathogenesis of hypertension development, as well as the effect of SNS on many biochemical and metabolic parameters playing a key role in the development of metabolic syndrome and hypertension are considered. Possible mechanisms of action of various methods that reduce the SNS activity, restore the function of autonomic nervous system and normalize the cardiovascular system and blood pressure are considered.
... • HRV (RMSSD and HF parameters): One previous study has shown Yoga Nidra to increase HRV when practiced after Hatha Yoga and when practiced without Hatha Yoga movements beforehand. 39 Thus, as a measure of autonomic nervous system response to our Yoga Nidra intervention, we are measuring HRV, specifically root mean square of successive differences between RR interva l s (RMSSD), and HF HRV parameters, which have been correlated with relaxation. 40 • Respiratory rate: As a measure of autonomic nervous system response to Yoga Nidra, we are measuring respiratory rate, which has been shown to decrease during meditation. ...
Extended sleep onset latency (SOL), or “sleep onset insomnia,” can decrease total sleep time, increasing risk for many health conditions, including heart disease, stroke, and all-cause mortality. Sleep disorders persist in the United States despite current behavioral/pharmaceutical remedies, with 10% to 15% of the population suffering from insomnia. Mind-body therapies offer additional solutions, as meditation has been correlated with decreased SOL. More research on use of mind-body practices for insomnia is needed. This study investigates the guided meditation practice of Yoga Nidra (yogic sleep) as a promising intervention for sleep disorders because of its purported ability to induce mental, physical, and emotional relaxation. In this pilot study, we address the feasibility of Yoga Nidra for insomnia, appropriateness of our selected measurement systems, and effect of Yoga Nidra on brainwaves, sleep onset, and the autonomic nervous system. Our study sample includes 22 adults, ages 18–45, with insomnia. The design includes two clinic visits (V1, lying quietly for 90 min; V2, randomization to 90-min lying quietly vs. 30-min Yoga Nidra plus 60-min lying quietly), taking place 1 to 14 days apart. Outcomes measured during/after Yoga Nidra (vs. control) include sleep onset, electroencephalography (EEG) power, heart rate variability (HRV), and respiratory rate. Self-reported mood and anxiety will be measured before/after each visit. Resulting physiological, psychological, and feasibility data will be used to inform future clinical studies of Yoga Nidra for sleep and relaxation.
... al., 2010;Ruprai, et. al., 2012); " yoga and the heart" (Lakkireddy, et al., 2013;Lin, et al., 2015;Markil, et al., 2012;Pullen, et al., 2008;Sarang, et al., 2006). These scientific "advancements" in yoga are guided by morally ambiguous imperatives from within the ivory tower. ...
This study unearths 20th-century U.S. music histories to demonstrate that racism accompanied the entry of yoga into American “belonging” and domestication, while “Indians” were excluded. There are three yoga song sites in this study; each presents a composite of racial constructions that utilize Othering tropes long deployed to affirm White supremacy and legitimize colonial power. I analyze the sound world, lyrics, and films of (1) the 1941 popular song “The Yogi Who Lost His Will Power,” by Orrin Tucker and His Orchestra; (2) the 1960 chart-topper “Yogi,” which catapulted the Ivy Three to one-hit-wonder status; and, (3) the 1967 Elvis Presley song “Yoga Is as Yoga Does, ” from the movie Easy Come, Easy Go. Questions that guide this study include: How does racist displacement appear in historic contexts of sonic productions and U.S. proliferation in yoga? What racial stereotypes accompanied yoga’s entry into American cultural discourse? I argue the evidence supports three key findings: (1) yoga’s movement into American popular culture is inextricably tied to racism and Othering; (2) widely circulating stereotypes of Indians, yoga, and yogis in American popular music include classic racist tropes, such as the grinning Sambo, and (3) the logic of elimination operates to hide U.S. music histories of racialized yoga. I conclude that U.S. yoga and its musical and cultural productions, branded as peaceful and flexible, camouflage the settler nation and White supremacy. The article concludes with a forecast for the importance of music studies to the nascent field of critical yoga studies.
... 11,12 Because of some studies' findings, the combination of relaxation strategies and Hatha yoga has shifted in autonomic balance along the continuum from the sympathetic to the parasympathetic branch of the ANS. 13,14 To that end, researchers have argued that yoga may promote parasympathetic activation that leads to reduced HR and BP and improved HRV, together with other metabolic and psychological benefits, including decreased levels of depression, 15 improved quality and quantity of sleep, 16 decreased risk for metabolic syndrome, 17 and weight reduction in the form of decreased visceral fat. 18,19 The purpose of the current study was to delineate the immediate cardiovascular effects of 12 Hatha yoga poses by means of RR and JT intervals. ...
Context:
Yoga as a form of physical activity is growing in popularity. During yoga, individuals interrupt the stress response, which is typically associated with high blood pressure (BP), impaired focus, and high levels of anxiety. Consequently, research into yoga's effects on stress should place a special emphasis upon the interplay of the nervous and cardiovascular systems during yoga practice.
Objective:
The purpose of this study was to delineate the immediate cardiovascular effects of 12 Hatha yoga poses by means of RR (beat-to-beat) intervals and JT (cardiac repolarization) intervals.
Design:
The research team designed controlled pilot studies based on half-year periods.
Setting:
The study took place at the Lithuanian University of Health Sciences in Kaunas, Lithuania.
Participants:
Participants were women who were long-term yoga practitioners. Three studies occurred: (1) Study 1-10 women with a mean age of 30.1 ± 1.9 years, (2) Study 2-10 women with a mean age of 29.9 ± 1.9 years, and (3) Study 3-22 women with a mean age of 32.9 ± 1.8 years.
Intervention:
The study examined the acute cardiovascular effects of 12 Hatha yoga poses by means of electrocardiogram parameters.
Outcome measures:
Anthropometrical and physiological parameters were measured: (1) height and weight; (2) body mass index (BMI); (3) heart rate (HR); (4) systolic and diastolic blood pressure (DBP); and (5) electrocardiogram (ECG) RR and JT intervals.
Results:
The lowest RR interval value was recorded during the Chaturanga Dandasana, at 456.0 ± 16.5 ms in Study 3, with P < .001 compared to the intervals for all the other poses. Significant differences in the JT interval also emerged during the Chaturanga Dandasana, at 177.3 ± 6.0 ms in Study 3 with P < .001 compared to all the other poses. The next lowest RR interval value was recorded in Study 3 during the Utkatasana, at 569.4 ± 17.6 ms. In the Savasana prior to the program, the RR interval increased in study 1 and decreased in studies 2 and 3. The JT interval in the Savasana prior to the program increased in studies 1 and 2 but decreased in study 3.
Conclusions:
Healthy women can practice a modified and/or a shorter duration of the Chaturanga Dandasana. Adjustments in the Utkatasana, including having the arms in the prayer position, may help prevent strain to the cardiovascular system. Also, practicing poses with a longer RR interval may aid stress-related health problems.
... As a percentage of TIB, SWS showed a moderate effect in PSG parameters. Yoga nidra has been found to be associated with a shift towards parasympathetic dominance, 28 and high cardiac vagal control is related to better subjective and objective sleep quality. 29 Yoga practice in the morning has been found to increase parasympathetic drive at night, 30 causing sleep to be more restorative. ...
... [42,43] Conversely, advanced practitioners of yoga and Tantra have shown the ability to exert conscious control over what are thought to be "autonomic" functions such as pulse and heart rate variability. [44][45][46] Based on these findings, it is prudent to keep open the possibility that the chakras represent some experiential aspects of neurological functioning. ...
Background and aims:
Many studies have conclusively proven that meditative techniques derived from the Indian systems of philosophy, meditation and ritual classified as "Tantra" can bring about sustained changes in the structure and function of the nervous system of practitioners. The aim of this study is to provide neuroscientists a framework through which to interpret Tantra, and thereby provide a foundation upon which future interdisciplinary study can be built.
Methods:
We juxtapose Tantric concepts such as the subtle body, nadis and mantras with relevant neuroscientific findings. Our premise is that through sustained internalization of attention, Tantric practitioners were able to identify and document subtle changes in their field of awareness, which usually do not cross the threshold to come into our perception.
Results:
The descriptions left by Tantric philosophers are often detailed and empirical, but they are about subjective phenomena, rather than external objects. They also focus on individual experiences, rather than the group-level analyses favored by modern medical science.
Conclusion:
Systematic exploration of Tantric texts can be of tremendous value in expanding our understanding of human beings' experiential reality, by enabling us to build bridges between first-person and third-person approaches to the nervous system. This may open up new avenues for cognitive enhancement and treating neurological diseases.
... Im Vergleich zur Rückenschule sprechen die bisherigen Forschungsergebnisse für eine Gleichwertigkeit der Verfahren. Yoga kann also eine Alternative zu anderen Formen körperlicher Aktivität darstellen und wird als solche auch in der aktuellen Nationalen Versorgungsleitlinie empfohlen [5] Das parasympathische System scheint dabei spezifisch durch langsame Atemtechniken, Entspannung und Meditation, weniger durch die Yogahaltungen aktiviert zu werden [8]. Entsprechend zeigen Metaanalysen positive Wirkungen des Yoga bei Hypertonie-Patienten, jedoch nur bei den Interventionen, die insbesondere auf Atmung und Meditation fokussieren [9] ...
Yoga wird vermehrt in Prävention und Therapie eingesetzt – und zum Teil sogar von den Krankenkassen bezuschusst. Doch hält Yoga, was er verspricht, oder überwiegen die Risiken den Nutzen? Eine stetig wachsende Evidenzbasis widmet sich dieser Frage und kann helfen, individuelle Empfehlungen zu erarbeiten.
... In several early observational studies [22][23][24][25][26] with cross-sectional design, the results showed that Tai Chi/Yoga has the potential to enhance HRV through increased parasympathetic modulation [22,23] and/or to reduce sympathetic activity [24][25][26]. To further substantiate the potential beneficial effect of prolonged Tai Chi/Yoga training for autonomic nervous function, a growing number of experimental studies have recently been conducted [27][28][29][30][31][32][33]. As the number of trials increases, two research groups attempted to systematically evaluate the existing literature regarding the effects of Tai Chi [34] or Yoga [35] on HRV. ...
Background: Heart rate variability (HRV) as an accurate, noninvasive measure of the Autonomous Nervous System (ANS) can reflect mental health (e.g., stress, depression, or anxiety). Tai Chi and Yoga (Tai Chi/Yoga), as the most widely practiced mind-body exercises, have shown positive outcomes of mental health. To date, no systematic review regarding the long-lasting effects of Tai Chi/Yoga on HRV parameters and perceived stress has been conducted. Objective: To critically evaluate the existing literature on this topic. Methods: Five electronic databases (Web of Science, PubMed, Scopus, SportDiscus and Cochrane Library) were searched from the start of the research project to July 2018. Study selection, data extraction, and study quality assessment were independently carried out by two reviewers. The potentially identified randomized controlled trials (RCT) reported the useful quantitative data that were included only for meta-analysis. Results: meta-analysis of 17 medium-to-high quality RCTs showed significantly beneficial effects on HRV parameters (normalized low-frequency, Hedge's g = −0.39, 95% CI −0.39 to −0.56, p < 0.001, I2 = 11.62%; normalized high-frequency, Hedge's g = 0.37, 95% CI 0.22 to −0.52, p < 0.001, I2 = 0%; low-frequency to high-frequency ratio, Hedge's g = −0.58, 95% CI −0.81 to −0.35, p < 0.001, I2 = 53.78%) and stress level (Hedge's g = −0.80, 95% CI −1.17 to −0.44, p < 0.001, I2 = 68.54%). Conclusions: Stress reduction may be attributed to sympathetic-vagal balance modulated by mind-body exercises. Tai Chi/Yoga could be an alternative method for stress reduction for people who live under high stress or negative emotions.
... Indeed, HRV increases in almost all forms of ContAct, consistent with the rVNS hypothesis. Different forms of meditation (e.g., body scan, FA, OM acem, zen) and mind-body exercises such as yoga, all show increases in vagal tone HRV in healthy participants (Ditto et al., 2006;Phongsuphap et al., 2008;Wu and Lo, 2008;Tang et al., 2009;Markil et al., 2012;Melville et al., 2012;Nesvold et al., 2012;Telles et al., 2013). One exception is a study that involved the earlier mentioned ''breath of fire'' (Peng et al., 2004) that showed a decrease in HF, LF and LF/HF ratio. ...
Contemplative practices, such as meditation and yoga, are increasingly popular among the general public and as topics of research. Beneficial effects associated with these practices have been found on physical health, mental health and cognitive performance. However, studies and theories that clarify the underlying mechanisms are lacking or scarce. This theoretical review aims to address and compensate this scarcity. We will show that various contemplative activities have in common that breathing is regulated or attentively guided. This respiratory discipline in turn could parsimoniously explain the physical and mental benefits of contemplative activities through changes in autonomic balance. We propose a neurophysiological model that explains how these specific respiration styles could operate, by phasically and tonically stimulating the vagal nerve: respiratory vagal nerve stimulation (rVNS). The vagal nerve, as a proponent of the parasympathetic nervous system (PNS), is the prime candidate in explaining the effects of contemplative practices on health, mental health and cognition. We will discuss implications and limitations of our model.
Aim:
The purpose of this paper was to review and synthesize published research articles that have utilized yoga nidra as an intervention.
Background:
Yoga nidra is a form of guided meditation that has emerged in the literature in the past two decades as an intervention for a variety of medical conditions such as stress and mental health. It differs from traditional yoga, in that it does not require yoga poses. It is a noninvasive, cost-effective approach that is also easily accessible so it can be done in the privacy and comfort of the home.
Design:
The integrative review methodology by Whittemore and Knafl (2005) provided the framework for this review.
Methods:
The databases CINAHL, PubMed, SCOPUS, and PsycINFO were used to search for articles. Inclusion criteria consisted of journal articles in English with no limitations on dates of publication. Studies were excluded if any form of traditional yoga requiring poses was used as an intervention. Also excluded were all types of meditation that were not yoga nidra, systematic reviews, studies that utilized multiple intervention types (i.e., traditional yoga and yoga nidra), and commentaries/brief reports. Twenty-nine studies met the inclusion criteria. Quality appraisal was completed for each study.
Results:
The 29 studies that were reviewed consisted of 12 randomized controlled trials, 13 quasi-experimental studies, 3 mixed-methods studies, and 1 qualitative study. Outcome variables were categorized according to themes and results were systemically synthesized and reported by theme: (a) stress, (b) mood, (c) well-being, (d) psychologic dysfunction, (e) biomarkers, (f) sleep, and (g) miscellaneous.
Conclusion:
Yoga nidra was found to be effective in most of these studies. However, there was some clinical heterogeneity in the sample populations and intervention session lengths, frequencies, and durations, making it difficult to draw conclusions about yoga nidra intervention based solely on the findings presented in this review. More studies are needed overall, particularly ones with larger sample sizes and stronger experimental designs.
Clinical relevance:
Yoga nidra has the potential to be a useful, noninvasive, nonpharmacologic treatment or adjunct for a variety of conditions, particularly mental health.
Amaç: Bu araştırmada, menopozal dönemdeki kadınlarda egzersizin menopozal semptomlara etkisine ilişkin çalışmaların sistematik olarak incelenmesi amaçlandı. Yöntem: Sistematik derleme niteliğinde olan çalışmanın evrenini Ocak 2016-Ekim 2020 tarihleri arasında Google Scholar, EBSCO, MEDLİNE, Scopus, Ulakbim kaynaklarından taranarak ulaşılan 490 makale oluşturdu. Bu veri tabanlarındaki makaleleri taramak için ‘menopoz, klimakteriyum, menopoz ve egzersiz, menopozal semptomlar ve egzersiz, menopause, menopause and exercise ’anahtar kelimeleri kullanıldı. Bulgular: Taramalar sonucunda toplam 490 makaleye ulaşılmış olup, araştırmaya dahil edilme kriterlerini taşıyan 9 makale araştırmanın örneklemini oluşturdu. Egzersizin menopozal dönemdeki uyku bozukluğunun giderilmesinde, yaşam kalitesinin arttırılmasında, cinsel işlev kaybını önlenmesinde kullanıldığı belirtildi. Sonuç: Bu sistematik derlemede, birbirinden farklı sürelerde ve farklı yöntemler ile yapılan egzersiz çeşitlerinin menopozal semptomlar üzerinde etkili olduğu, ancak bu konuda daha fazla deneysel çalışmaya gereksinim bulunduğu sonucuna varılmıştır.
Introduction Structured exercise, as a therapeutic intervention, is central to cardiac rehabilitation (CR).1 Following myocardial infarction (Ml), cardiac autonomic activity becomes disordered, often resulting in loss ofvagal reflexes and increased sympathetic activity.2 Sympathetic hyperactivity predisposes towards ventricular fibrillation, while vagal reflexes are considered to have a cardio-protective effect.3 The activity of the autonomic nervous system (ANS) can be measured non-invasively by analysis of heart rate variability (HRV), which is a characteristic that can potentially be increased by physical activity.4 Coarse-graining spectral analysis (CGSA) of HRV is a sensitive, non-invasive technique commonly used to evaluate cardiac autonomic activity.5 HRV allows the examination of parasympathetic and sympathetic function via the analysis of the various components of the frequency domain. High frequency spectral power (HF, 0.15-0.40 Hz) is generally considered to be a measure of cardiac parasympathetic modulation, whereas low frequency power (LF, 0.04-0.15 Hz) reflects both parasympathetic and sympathetic control.6 The purpose of this study was to determine the effects of a predominantly exercise-based cardiac rehabilitation programme over a six-month period on cardiac autonomic modulation, using power spectral analysis of HRV.
Heart rate variability (HRV) was studied in cyclic meditation (CM) and supine rest (SR). CM included yoga postures followed by guided relaxation. Forty-two male volunteers were assessed in CM and SR sessions of 35 minutes, where CM or SR practice was preceded and followed by 5 minutes of SR. During the yoga postures of CM and after CM, low frequency power and the low frequency to high frequency power ratio decreased, whereas high frequency power increased. Heart rate increased during the yoga postures and decreased in guided relaxation and after CM. There was no change in SR. Hence, it appeared that predominantly sympathetic activation occurred in the yoga posture phases of CM while parasympathetic dominance increased after CM. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
This study investigated heart rate variability (HRV) in healthy volunteers that were selected for extreme scores of trait anxiety (TA), during two opposite psychophysiological conditions of mental stress, and relaxation induced by autogenic training. R-R intervals, HF and LF powers, and LF/HF ratios were derived from short-term electrocardiographic recordings made during mental stress and relaxation by autogenic training, with respiratory rate and skin conductance being controlled for in all the analyses. The main finding was that high TA was associated with reduced R-R intervals and HF power across conditions. In comparison to mental stress, autogenic training increased HRV and facilitated the vagal control of the heart. There were no significant effects of TA or the psychophysiological conditions on LF power, or LF/HF ratio. These results support the view that TA, which is an important risk factor for anxiety disorders and predictor of cardiovascular morbidity and mortality, is associated with autonomic dysfunction that seems likely to play a pathogenetic role in the long term.
R-R interval variability (RR variability) is increasingly being used as an index of autonomic activity. High-frequency (HF) power reflects vagal modulation of the sinus node. Since vagal modulation occurs at the respiratory frequency, some investigators have suggested that HF power cannot be interpreted unless the breathing rate is controlled. We hypothesized that HF power during spontaneous breathing would not differ significantly from HF power during metronome-guided breathing. We measured HF power during spontaneous breathing in 20 healthy subjects and 19 patients with heart disease. Each subject's spontaneous breathing rate was determined, and the calculation of HF power was repeated with a metronome set to his or her average spontaneous breathing rate. There was no significant difference between the logarithm of HF power measured during spontaneous and metronome-guided breathing [4.88 +/- 0.29 vs. 5.29 +/- 0.30 ln(ms(2)), P = 0.32] in the group as a whole and when patients and healthy subjects were examined separately. We did observe a small (9.9%) decrease in HF power with increasing metronome-guided breathing rates (from 9 to 20 breaths/min). These data indicate that HF power during spontaneous and metronome-guided breathing differs at most by very small amounts. This variability is several logarithmic units less than the wide discrepancies observed between healthy subjects and cardiac patients with a heterogeneous group of cardiovascular disorders. In addition, HF power is relatively constant across the range of typical breathing rates. These data indicate that there is no need to control breathing rate to interpret HF power when RR variability (and specifically HF power) is used to identify high-risk cardiac patients.
To evaluate effects of Hatha yoga and Omkar meditation on cardiorespiratory performance, psychologic profile, and melatonin secretion.
Thirty healthy men in the age group of 25-35 years volunteered for the study. They were randomly divided in two groups of 15 each. Group 1 subjects served as controls and performed body flexibility exercises for 40 minutes and slow running for 20 minutes during morning hours and played games for 60 minutes during evening hours daily for 3 months. Group 2 subjects practiced selected yogic asanas (postures) for 45 minutes and pranayama for 15 minutes during the morning, whereas during the evening hours these subjects performed preparatory yogic postures for 15 minutes, pranayama for 15 minutes, and meditation for 30 minutes daily, for 3 months. Orthostatic tolerance, heart rate, blood pressure, respiratory rate, dynamic lung function (such as forced vital capacity, forced expiratory volume in 1 second, forced expiratory volume percentage, peak expiratory flow rate, and maximum voluntary ventilation), and psychologic profile were measured before and after 3 months of yogic practices. Serial blood samples were drawn at various time intervals to study effects of these yogic practices and Omkar meditation on melatonin levels.
Yogic practices for 3 months resulted in an improvement in cardiorespiratory performance and psychologic profile. The plasma melatonin also showed an increase after three months of yogic practices. The systolic blood pressure, diastolic blood pressure, mean arterial pressure, and orthostatic tolerance did not show any significant correlation with plasma melatonin. However, the maximum night time melatonin levels in yoga group showed a significant correlation (r = 0.71, p < 0.05) with well-being score.
These observations suggest that yogic practices can be used as psychophysiologic stimuli to increase endogenous secretion of melatonin, which, in turn, might be responsible for improved sense of well-being.
Relaxation techniques are established in managing of cardiac patients during rehabilitation aiming to reduce future adverse cardiac events. It has been hypothesized that relaxation-training programs may significantly improve cardiac autonomic nervous tone. However, this has not been proven for all available relaxation techniques. We tested this assumption by investigating cardiac vagal modulation during yoga.We examined 11 healthy yoga practitioners (7 women and 4 men, mean age: 43 +/- 11; range: 26-58 years). Each individual was subjected to training units of 90 min once a week over five successive weeks. During two sessions, they practiced a yoga program developed for cardiac patients by B.K.S. Iyengar. On three sessions, they practiced a placebo program of relaxation. On each training day they underwent ambulatory 24 h Holter monitoring. The group of yoga practitioners was compared to a matched group of healthy individuals not practicing any relaxation techniques. Parameters of heart rate variability (HRV) were determined hourly by a blinded observer. Mean RR interval (interval between two R-waves of the ECG) was significantly higher during the time of yoga intervention compared to placebo and to control (P < 0.001 for both). The increase in HRV parameters was significantly higher during yoga exercise than during placebo and control especially for the parameters associated with vagal tone, i.e. mean standard deviation of NN (Normal Beat to Normal Beat of the ECG) intervals for all 5-min intervals (SDNNi, P < 0.001 for both) and root mean square successive difference (rMSSD, P < 0.01 for both). In conclusion, relaxation by yoga training is associated with a significant increase of cardiac vagal modulation. Since this method is easy to apply with no side effects, it could be a suitable intervention in cardiac rehabilitation programs.
To examine the hypothesis that the relaxation response is associated with an increase in cardiac parasympathetic tone, the frequency components of heart rate variability during relaxation training were investigated in 16 college students. Electrocardiograms and pneumograms were recorded during a 5-min baseline period followed by three successive 5-min sessions of the autogenic training (relaxation) or by the same periods of quiet rest (control), while subjects breathed synchronously with a visual pacemaker (0.25 Hz). Although neither the magnitude nor the frequeney of respiration showed a significant difference between relaxation and control, the amplitude of the high-frequency component of heart rate variability increased only during relaxation (p= .008). There was no significant difference in the ratio of the low-frequency (0.04–0.15 Hz) to the high-frequency amplitudes. The increased high-frequency amplitude without changes in the respiratory parameters indicates enhanced cardiac parasympathetic tone. Thus, our results support the initial hypothesis of this study. Enhanced cardiac parasympathetic tone may explain an important mechanism underlying the beneficial effect of the relaxation response.
Background:
It is unclear from prior reports whether the relationships between self-ratings of anxiety or emotional stress and parasympathetic nervous system components of heart rate variability are independent of personality and cardiorespiratory fitness. We examined those relationships in a clinical setting prior to a standardized exercise test.
Methods and results:
Heart rate variability (HRV) was measured during 5 min of supine rest among 92 healthy men (N=52) and women (N=40) who had above-average cardiorespiratory fitness as indicated by peak oxygen uptake measured during grade-incremented treadmill exercise. HRV datasets were decomposed into low-frequency (LF; 0.05-0.15 Hz) and high-frequency (HF; 0.15-0.5 Hz) components using spectral analysis. Self-ratings of trait anxiety and perceived emotional stress during the past week were also assessed.
Conclusions:
There was an inverse relationship between perceived emotional stress during the past week and the normalized HF component of HRV (P=0.038). This indicates a lower cardiac vagal component of HRV among men and women who perceived more stress. That relationship was independent of age, gender, trait anxiety, and cardiorespiratory fitness. It was also independent of heart rate; mean arterial blood pressure; and respiration rate, factors which can influence HRV and might be elevated among people reporting anxiety and perceived stress. We conclude that vagal modulation of heart period appears to be sensitive to the recent experience of persistent emotional stress, regardless of a person's level of physical fitness and disposition toward experiencing anxiety.
In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90 degrees upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) beta-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at approximately 0.25 Hz and a low frequency at approximately 0.1 Hz, with a normalized low frequency:high frequency ratio of 3.6 +/- 0.7. With tilt, the low-frequency component became largely predominant (90 +/- 1%) with a low frequency:high frequency ratio of 21 +/- 4. Acute beta-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequency:high frequency ratio induced by tilt. Chronic beta-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequency:high frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequency:high frequency ratio (0.7 +/- 0.1); during tilt, the increase in the low frequency:high frequency ratio (8.3 +/- 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequency:high frequency ratio at rest of 2.8 +/- 0.7, which became 17 +/- 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increase in low frequency, as a result of reflex sympathetic activation.(ABSTRACT TRUNCATED AT 400 WORDS)
We present a useful technique for analyzing the various functional components that comprise the cardiovascular control network. Our approach entails the imposition of a signal with broad frequency content as an input excitation and the computation of a system transfer function using spectral estimation techniques. In this paper, we outline the analytical methods involved and demonstrate the utility of our approach in studying the dynamic behavior of the canine cardiac pacemaker. In particular, we applied frequency-modulated pulse trains to either the right vagus or the cardiac sympathetic nerve and computed transfer functions between nerve stimulation rate and the resulting atrial rate. We found that the sinoatrial node (and associated automatic tissue) responds as a low-pass filter to fluctuations in either sympathetic or parasympathetic tone. For sympathetic fluctuations, however, the filter has a much lower corner frequency than for vagal fluctuations and is coupled with a roughly 1.7-s pure delay. We further found that the filter characteristics, including the location of the corner frequency and rate of roll-off, depend significantly on the mean level of sympathetic or vagal tone imposed.
To 1) consider the problem of sudden death from heart disease and the role of beta-blockers and other agents in preventing sudden death and 2) review perceived problems with beta-blocker therapy, such as effects on blood lipids, complications in diabetes, and adverse effects on heart failure and quality of life.
MEDLINE and EMBASE searches done from July 1994 on, and recognized texts.
More than 400 original and review articles were evaluated, of which the most relevant were selected.
Data were extracted and reviewed by two authors. Accuracy was confirmed, when necessary, by the other authors.
Of all of the therapies currently available for the prevention of sudden cardiac death, none is more established or more effective than beta-blockers. Indeed, the evidence that beta-blockers have a cardioprotective effect is compelling. They probably reduce the rate of atheroma formation; they reduce the risk for ventricular fibrillation in animal models of myocardial ischemia; they appear to reduce cardiac mortality in primary prevention trials; and they reduce mortality, particularly from sudden death, in patients who have had infarction. Moreover, withholding beta-blockers because of problems perceived to be associated with them is usually not warranted and may frequently prevent their use in those who will benefit most from them.
Clinicians should reappraise the evidence for the significant effect of beta-blockers on morbidity and mortality, and they should recognize the importance of initiating and maintaining beta-blocker therapy when the less well-informed might suggest otherwise.
Seven conscious dogs documented to be at high risk by the occurrence of ventricular fibrillation (VF) during acute myocardial ischemia were randomly assigned to 6 weeks of either daily exercise training or cage rest followed by exercise training. After 6 weeks of daily treadmill training, heart rate variability, a marker of vagal tone, increased by 74% (P < .001); baroreflex sensitivity, a marker of the capability to reflexly augment vagal activity, increased by 69% (P < .01); the repetitive extrasystole threshold, a marker of ventricular electrical stability, increased by 44% (P < .05). After exercise training, the incidence of ventricular fibrillation during acute myocardial ischemia decreased by 100%, as all animals survived. Neither passage of time nor heart rate level during ischemia contributed to the outcome. The most likely mechanism to explain the striking change in risk status is the shift in autonomic balance characterized by increased cardiac vagal activity, which was previously shown to have an antifibrillatory effect. These results suggest that exercise training in healthy individuals may decrease their likelihood of developing lethal arrhythmias during acute myocardial ischemia.
We report extremely prominent heart rate oscillations associated with slow breathing during specific traditional forms of Chinese Chi and Kundalini Yoga meditation techniques in healthy young adults. We applied both spectral analysis and a novel analytic technique based on the Hilbert transform to quantify these heart rate dynamics. The amplitude of these oscillations during meditation was significantly greater than in the pre-meditation control state and also in three non-meditation control groups: i) elite athletes during sleep, ii) healthy young adults during metronomic breathing, and iii) healthy young adults during spontaneous nocturnal breathing. This finding, along with the marked variability of the beat-to-beat heart rate dynamics during such profound meditative states, challenges the notion of meditation as only an autonomically quiescent state.
This study was designed to investigate the effects of 12 wk of exercise training on autonomic nervous system (ANS) in 18 obese middle-aged men (N = 9) and women (N = 9) (age: 41.6 +/- 1.2 yr; BMI: 27.3 +/- 0.4 kg x m(-2); %fat: 29.6 +/- 1.3%, mean +/- SE).
Each subject participated in an aerobic exercise training at anaerobic threshold (AT), consisting of 30 min/session, 3 times/wk, for 12 consecutive weeks. The ANS activities were assessed by means of power spectral analysis of heart rate variability (HRV) at resting condition before, at 5 wk, and after the exercise program.
The exercise training resulted in a significant decrease in body mass, BMI, and % fat (P < 0.01) but not in lean body mass (P > 0.05) together with a significant increase in the AT VO2 (P < 0.01). Our power spectral data indicated that there were significant increases in the low-frequency component associated with the sympathovagal activity (0.03--0.15 Hz, 348.5 +/- 66.8 vs 694.7 +/- 91.5 ms(2), P < 0.01), the high-frequency vagal component (0.15--0.4 Hz, 146.3 +/- 30.4 vs 347.7 +/- 96.5 ms(2), P < 0.05), and the overall autonomic activity as evaluated by total power (0.03--0.4 Hz, 494.8 +/- 88.5 vs 1042.4 +/- 180.9 ms(2), P < 0.01) of HRV after the training.
Twelve weeks of exercise training has significantly improved both the sympathetic and parasympathetic nervous activities of the obese individuals with markedly reduced ANS activity, suggesting a possible reversal effect of human ANS functions. These favorable changes may also have an influence on the thermoregulatory control over the obesity.
To test whether rhythmic formulas such as the rosary and yoga mantras can synchronise and reinforce inherent cardiovascular rhythms and modify baroreflex sensitivity.
Comparison of effects of recitation of the Ave Maria (in Latin) or of a mantra, during spontaneous and metronome controlled breathing, on breathing rate and on spontaneous oscillations in RR interval, and on blood pressure and cerebral circulation.
Florence and Pavia, Italy.
23 healthy adults.
Breathing rate, regularity of breathing, baroreflex sensitivity, frequency of cardiovascular oscillations.
Both prayer and mantra caused striking, powerful, and synchronous increases in existing cardiovascular rhythms when recited six times a minute. Baroreflex sensitivity also increased significantly, from 9.5 (SD 4.6) to 11.5 (4.9) ms/mm Hg, P<0.05.
Rhythm formulas that involve breathing at six breaths per minute induce favourable psychological and possibly physiological effects.
The aim of the study was to investigate the effects of menstrual cycle on cardiac autonomic function parameters in young healthy women by means of heart rate variability (HRV).
Forty-three nonobese regularly cycling women (age 29 +/- 6, range 20-38) were enrolled. Recordings for HRV analysis were obtained during the two phases of the menstrual cycle when the estrogen and progesterone levels peaked (follicular phase 11 +/- 1 days and luteal phase 21 +/- 1 days from the start of bleeding). Power spectral analysis of HRV was performed to calculate the low frequency peak (LF, 0.04-0.15 Hz), high frequency peak (HF, 0.15-0.40 Hz), LF in normalized unit (LF nU), HF in normalized unit (HF nU), and LF/HF ratio during the two phases of menstrual cycle.
The heart rates, LF and HF, were similar in both phases (P > 0.05). A significant increase was noted in the LF NU in the luteal phase compared to follicular phase of the menstrual cycle (P = 0.014), whereas a tendency for increased HF NU was observed in the follicular phase (P = 0.053). Furthermore, LF/HF ratio was significantly higher in the luteal phase compared to follicular phase (2.1 +/- 1.5 vs 1.6 +/- 0.9, P = 0.002), suggesting increased sympathetic activity in the luteal phase.
We concluded that regulation of autonomic tone is modified during menstrual cycle. The alteration in the balance of ovarian hormones might be responsible for these changes in the cardiac autonomic innervation.
Regular exercise is associated with increased heart rate variability (HRV). However, results from studies examining the effect of exercise training on HRV in postmenopausal women are inconclusive. In addition, the effect of hormone replacement therapy (HRT) on HRV remains a subject of speculation.
We examined 88 sedentary postmenopausal women in a randomized controlled trial who were assigned to exercise (n = 49) or control (n = 39) groups. The exercising women performed 8 weeks of aerobic exercise training at a heart rate equivalent to 50% of VO2max, consisting on average of 44 minutes per session, 3 to 4 times per week. Resting HRV was measured in each participant at baseline and after 8 weeks of intervention. Ten minutes of resting R-R intervals were analyzed by time (standard deviation of mean R-R intervals, root of mean square successive differences) and frequency domain methods: low-frequency (LF) was defined as 0.04 to 0.15 Hz, high-frequency (HF) as 0.15 to 0.40 Hz, and total spectral power as 0.00 to 0.40 Hz. The LF and HF components in normalized units were also calculated.
At baseline, there were no significant differences in HRV between control and exercise groups. Additionally, there were no differences in any HRV variables when women were grouped by HRT use (no HRT, estrogen-only HRT, and progestin-containing HRT). After 8 weeks, women randomly assigned to the exercise group increased all absolute time and frequency domain indexes (all P <.001) and reduced resting heart rate (P =.002) compared with women in the control group. The LF and HF components expressed as normalized units remained unchanged after exercise intervention. Additionally, HRT use did not modify the exercise-induced changes in HRV.
We conclude that moderate aerobic exercise increases HRV in sedentary postmenopausal women. This benefit is not influenced by the use of HRT.
This study was designed to quantify and compare the instantaneous heart rate dynamics and cardiopulmonary interactions during sequential performance of three meditation protocols with different breathing patterns.
We analyzed beat-to-beat heart rate and continuous breathing signals from 10 experienced meditators (4 females; 6 males; mean age 42 years; range 29-55 years) during three traditional interventions: relaxation response, breath of fire, and segmented breathing.
Heart rate and respiratory dynamics were generally similar during the relaxation response and segmented breathing. We observed high amplitude, low frequency (approximately 0.05-0.1 Hz) oscillations due to respiratory sinus arrhythmia during both the relaxation response and segmented breathing, along with a significantly (p<0.05) increased coherence between heart rate and breathing during these two maneuvers when compared to baseline. The third technique, breath of fire, was associated with a different pattern of response, marked by a significant increase in mean heart rate with respect to baseline (p<0.01), and a significant decrease in coherence between heart rate and breathing (p<0.05).
These findings suggest that different meditative/breathing protocols may evoke common heart rate effects, as well as specific responses. The results support the concept of a "meditation paradox," since a variety of relaxation and meditative techniques may produce active rather than quiescent cardiac dynamics, associated with prominent low frequency heart rate oscillations or increases in mean resting heart rate. These findings also underscore the need to critically assess traditional frequency domain heart rate variability parameters in making inferences about autonomic alterations during meditation with slow breathing.
Chronic exercise training has been shown to have a positive influence on cardiac autonomic function as assessed by measures of heart rate variability (HRV). Recent evidence indicates that several benefits associated with exercise training (e.g., improved insulin action, reduced blood pressure, improved blood lipid profile) may be realized transiently after a single bout of exercise. As many of these effects of recent exercise are linked to cardiovascular control systems, the purpose of this investigation was to test the hypothesis that a single bout of exercise would result in favorable changes in cardiac autonomic function as assessed by frequency-domain measures of HRV.
Subjects were 11 healthy male volunteers ages 18-35 yr. Resting HRV measures were obtained during 5 min of paced breathing before and 1, 3, 6, and 22 h after a 60-min bout of cycling exercise at approximately 65% of peak oxygen uptake. Identical measures were obtained in a nonexercise condition based on a randomized crossover design.
Exercise resulted in increased high-frequency HRV, decreased low-frequency HRV, and consequently a decrease in the ratio of low-frequency to high-frequency HRV compared with the nonexercise condition. Additionally, a time-domain measure of HRV (pNN50) was markedly higher in the exercise condition as compared to nonexercise.
The changes in cardiac autonomic function observed are similar to those seen in investigations of long-term training. These changes indicate a shift in autonomic function toward increased parasympathetic nervous system activity and decreased sympathetic nervous system activity, suggesting a more stable autonomic environment for the heart. These results may provide further evidence of the cardioprotective effects of a single bout of submaximal exercise.
Heart rate variability (HRV) is a simple noninvasive measurement for investigating autonomic influence on the cardiovascular system. HRV, the beat-to-beat alterations in heart rate, may be evaluated by time domain and frequency domain methods. HRV can be used as a predictor of risk or warning sign of cardiovascular diseases. Numerous studies have shown that a reduced HRV can also be used as a predictor of hypertension, development of diabetic neuropathy, cerebrovascular disease, congestive heart failure, and lethal arrhythmic complications after an acute myocardial infarction. A few studies have also revealed that relaxation techniques can increase HRV. This article reviews the literature about HRV measurement and the relationships among HRV, hypertension, and relaxation techniques. Limitations of the review literature have also been considered to identify areas for future research.
Chronic exercise training produces a resting bradycardia that is thought to be due partly to enhanced vagal modulation.
The aim of the present study was to determine the effects of exercise training on heart rate and measures of heart rate variability associated with vagal cardiac modulation and to quantify the relationship between changes in these measures.
A random effects model of effect size (d) for change in high frequency (HF) power and RR interval was calculated. Within-group heterogeneity was assessed using the Q statistic. Where heterogenous effects were found, subgroup analyses were performed using the between-group Q statistic.
A meta-analysis of 13 studies measuring HF (N=322 cases) produced an overall effect size of d=0.48 (C.I. 0.26-0.70, P=0.00003). Twelve studies (298 cases) reported a change in RR interval with an overall effect size of d=0.75 (C.I. 0.51-0.96, P<0.00001). Effect sizes for RR interval data were significantly heterogenous. Subgroup analysis revealed significantly smaller responses of RR interval to training in older subjects (P<0.1). Effect sizes for change in HF were homogenous, although a trend toward an attenuated response to training was exhibited in older subjects (P>0.10). Linear, quadratic, and cubic fits all revealed weak (P>0.05) relationships between effect sizes for change in HF and RR interval.
Exercise training results in significant increases in RR interval and HF power. These changes are influenced by study population age. The smaller effect size for HF and weak relationship between HF and RR interval suggest factors additional to increased vagal modulation are responsible for training bradycardia.
The existence of specific somatic states associated with different emotions remains controversial. In this study, we investigated the profile of cardiorespiratory activity during the experience of fear, anger, sadness and happiness. ECG and respiratory activity was recorded in 43 healthy volunteers during the recall and experiential reliving of one or two potent emotional autobiographical episodes and a neutral episode. Univariate statistics indicated that the four emotions differed from each other and from the neutral control condition on several linear and spectral indices of cardiorespiratory activity. Dependent variables were further reduced to five physiologically meaningful factors using an exploratory principal component analysis (PCA). Multivariate analyses of variance and effect size estimates calculated on those factors confirmed the differences between the four emotion conditions. A stepwise discriminant analyses predicting emotions using the PCA factors led to a classification rate of 65.3% for the four emotions (chance=25%; p=0.001) and of 72.0-83.3% for pair-wise discrimination (chance=50%; p's<0.05). These findings may be considered preliminary in view of the small sample on which the multivariate approach has been applied. However, this study emphasizes the need to better characterize the multidimensional factors involved in cardio-respiratory regulation during emotion. These results are consistent with the notion that distinct patterns of peripheral physiological activity are associated with different emotions.
In this study, we investigated heart rate variability in women who exercise regularly, but with differing volumes of physical activity. Forty women participated and were allocated to either a "high" or "moderate" activity group. Heart rate as R-R intervals was recorded during supine rest and analysed using time domain, frequency domain, and Poincaré plot techniques. All time domain and Poincaré analysis measures revealed significant differences in heart rate variability between the "high" and "moderate" activity groups. Frequency domain analysis also revealed a significant difference between the two groups in absolute measures of high-frequency and low-frequency power, but not between measures such as the low-frequency/high-frequency ratio, proposed to represent the sympathetic/parasympathetic balance of cardiac control. The results demonstrate that there is a significant difference in heart rate variability between women who engage in "high" compared with "moderate" volumes of physical activity, which may have implications for cardiac autonomic health.
12 Values are mean – standard deviation. *p £ 0.05; postrelaxation, compared to baseline. YR baseline = baseline measures for yoga plus relaxation condition (last 5 minutes). YR relaxation = relaxation phase for yoga plus relaxation condition
2546.05 – 1306.18 2312.90 – 1594.56 3090.74 – 2298.12 Values are mean – standard deviation. *p £ 0.05; postrelaxation, compared to baseline. YR baseline = baseline measures for yoga plus relaxation condition (last 5 minutes). YR relaxation = relaxation phase for yoga plus relaxation condition (last 5 minutes).
Cardiac autonomic function and incident coronary artery disease: A population based case cohort study: The ARIC Study
- D Liao
- Rosamund C Jianwen
- Wd
Liao D, Jianwen C, Rosamund WD, et al. Cardiac autonomic function and incident coronary artery disease: A population based case cohort study: The ARIC Study. Am J Epidemiol 1997;145:696–706.