Yoga-nidrā: A State of Mind, Not a Technique

Abstract

Since its introduction to the West in 1969 by Swāmī Rāma through experiments conducted at the U.S. Menninger Foundation, yoga-nidrā has become a popular practice among yoga teachers from many traditions. The result is a patchwork of techniques incorporating a variety of practices and procedures. It has come to be thought of primarily as technique and the variability of techniques across traditions has engendered debate about which technique is right. In fact, yoga-nidrā is defined by Swāmī Rāma, as well as by textual sources, as a state of mind where the practitioner consciously enters a state of deep, dreamless (non-REM) sleep, remaining both inwardly aware and aware of their external surroundings. The more a practitioner has managed to keep the parasympathetic relaxation system continuously activated through moment-to-moment mindfulness practice, the less technique is required to enter that state. The only way to be certain that someone has entered this state is to measure their brain waves with an electro-encephalogram (EEG) for predominance of delta waves and to test their awareness of their surroundings. For purposes of getting to the state of yoga-nidrā, any of the preparatory techniques will serve, although none are a guarantee that the state will be reached.

1. Introduction

Swāmī Rāma of the Himālayas first appeared in the United States in 1969. One of his hosts, Daniel Ferguson M.D., connected him to the Voluntary Controls Project of Drs. Elmer and Alyce Green at the Menninger Foundation, a psychiatric research institution that had begun to investigate mind–body interactions [1] Swāmī Rāma’s intention was to demonstrate to people in the West what a human being can achieve through the kind of mental mastery provided by yoga. As part of this project, he agreed to demonstrate all of the different brain wave states. At this time there was great interest in alpha-wave states as a way to use technology to help people induce deep relaxation. He not only demonstrated alpha-wave states, but went on to demonstrate theta- and delta-wave states as well, something that the science of the time hardly thought possible through conscious effort. In the demonstration of the delta-wave state (deep, dreamless sleep), his brain waves were monitored by an electroencephalogram (EEG). Most surprising was that, during the experiment, two lab technicians were having a conversation nearby, and when Swāmī Rāma came out of the yoga-nidrā state, he was able to recount their conversation word-for-word. In that experiment he used no technique to enter that mental state. When he taught yoga-nidrā publically, however, he taught a series of relaxation practices as necessary preliminaries for people who had not otherwise learned to keep their minds continually still, clear, relaxed and aware [2].

One of Swāmī Rāma’s more advanced disciples, Swāmī Veda Bhāratī, formerly Dr. Uṣarbudh Ārya, endeavored in 2006 to replicate that experiment in the laboratory of Dean Radin Ph.D. at the Institute for Noetic Sciences in Petaluma, CA [3]. As Radin recounts, he realized as they were talking before the formal experiment, that the EEG was already running and Swāmī Veda was producing almost pure delta waves as they talked! This was extraordinary as neuroscience would predict that the delta-wave state is one where the subject remains unconscious as all the neurons in their nervous system fire synchronously. This persuaded Radin that it was very likely that Swāmī Veda remained in a state of yoga-nidrā most or all of the time, waking or sleeping (p. 69). As a result of his training by Swāmī Rāma, Swāmī Veda recognized that he had been using states of yoga-nidrā without knowing what they were since early childhood [4]. Later in life, he would often pause in the midst of a lecture (“just give me a minute”) to use yoga-nidrā to stave off a cardiac crisis. In some form, this would occur daily during the last 20 years or so of his bodily life. (He once told the author that since his open heart surgery in 1992, he had not been without angina, cardiac heart pain, for one second.) Though cardiac pain was always present, he rarely showed it and remained joyful and even-minded to the public eye.

2. Swāmī Veda Bhāratī’s model for levels of practice

For a conference on yoga-nidrā in 2009, Swāmī Veda suggested a model for yoga-nidrā practice which had four levels ([5], pp. 11–12), described both experientially and with testable physiological hypotheses:

1. The first level comprises preparatory deep relaxation. It is characterized by a predominance of alpha waves measured via electroencephalography (8–13 Hz). Here one may accomplish significant psychophysiological changes including reduction of blood pressure and migraine headaches. This level is very similar to the states attained in clinical hypnosis. This author suspects that clinical hypnosis is a special case of yoga-nidrā.

2. The second level is characterized by a predominance of theta waves (4–8 Hz), verging on delta waves (0.5–4 Hz) at deeper levels of practice. This is the level at which one may work with creativity, making decisions, exercising intentions (saṁkalpa), doing invention and composition. This author observed Swāmī Veda dictating his commentary on the Yoga-sūtras of Patañjali from that state, which was his preferred process of writing.

3. In level three, the preparatory practices bring the practitioner to the state of yoga-nidrā proper. In the beginning there may be theta waves which eventually gives way to a predominance of delta waves (0.5–4 Hz) and the experience of observing deep, non-REM (rapid eye movement) sleep with both inner and outer awareness, from an inner cave in the heart center, anāhata-cakra. This is the experience of abhāva-pratyaya described in Yoga-sūtras I.10 [6]. Entering this state may require direct induction through a process of initiation by a qualified teacher.

4. Progression to level four requires mastery of the first three levels, meaning that the person can enter the state of yoga-nidrā with no technique and no preliminaries. This stage has no time limits. Practitioners often remain in this state up to 3.5 hours, the balance of his/her sleep taken in the ordinary manner. Mastery of all four levels brings the practitioner to the doorstep of turīya. Contrary to the claims of some teachers, Swāmī Veda always clearly explained that yoga-nidrā is not equivalent to turīya.

3. Research investigation of yoga-nidrā

In 2012 the author undertook an effort to assess the quality of scientific research on yoga-nidrā since it seemed to hold so much promise as a support to peoples’ physical and mental health and it provided testable hypotheses [5, 7, 8]. At that time there were only a very few published studies that measured subjects’ brain waves in order to ascertain whether the preparatory techniques utilized actually brought the subjects to the state of yoga-nidrā. Without this instrumentation, it really is not possible to objectively assess the effectiveness of any of the preparatory practices. These studies all demonstrated that subjects got deeply relaxed, but that is not hard to show through questionnaires, electromyography or measures of pulse or blood pressure, and this much has been done many times over. In the past several years, the experimental methodologies have begun to utilize brain wave measurement and other more rigorous methods (e.g. full polysomnographic sleep studies) and so the author has high hopes that this will provide significant results [9, 10]. In the studies cited, it already has.

4. Textual descriptions

The textual descriptions of yoga-nidrā are several and mention of yoga-nidrā dates from as early as the early Upaniṣads to the relatively late texts of haṭhayoga and systematic advaita-vedānta. The paucity of detail in the early texts can be attributed to the fact that the practice was taught master-to-disciple from the oral-initiatory tradition of yoga because the technique was always customized to the particular needs and abilities of the disciple ([11], pp. 786–811). In Bhagavad-gītā II.69, there is the cryptic verse about how yogis remain aware in what is night for ordinary beings and ordinary beings are active during what is night (= unconscious, habit-based living) to the yogis. Arjuna is also often referred to by Kṛṣṇa as Guḍakeṣa, “master of sleep,” one of the pre-requisites for the initiation he is given in chapter 11. The state of yoga-nidrā is described in several sources. Couture (1999) focuses primarily on the mythical literature in the Mahābhārata and Purāṇas. Parker et al. ([5], p. 13) and Pandi-Perumal et al. ([9], pp. 84–85) also utilize descriptions from the Yogatarāvali of Śaṅkarācārya, the Haṭhayogapradīpikā and Śāṇḍilya-upaniṣad. These later sources give a somewhat more detailed practical description of yoga-nidrā.

To summarize these descriptions, all three of these sources focus on activation of the suṣumnā-ṇāḍī, where the ordinary alternation of activity in the right and left nostrils is transcended and both nostrils remain equally open, indicating simultaneous activation of both cerebral hemispheres. The practitioner enters a state of unmani (“upward mind”) which, when extended, becomes yoga-nidrā. Some interpreters claim that this is a form of pratyāhāra, sensory withdrawal. This, however, is not the case as one of the features of yoga-nidrā demonstrated by Swāmī Rāma, is that the practitioner retains awareness of his/her surroundings. In pratyāhāra, the senses are entirely withdrawn from their external surroundings and sense objects and dissolve completely back into manas (Yoga-sūtra II.54) [11]. These texts also state that the activity of manas, the lower, sensory and thinking mind, ceases altogether. In other words, the lower sensory mind goes to sleep while the higher mind, buddhi, observes the process.

Śaṅkarācārya’s Yogatarāvali also encourages the practitioner to remain in a state of turīya. This has prompted some teachers to maintain that yoga-nidrā is turīya itself, the fourth state of consciousness in the Advaita system, or that it is a state of samādhi. Swāmī Veda often cautioned that neither of these is true. Turīya in particular, he said, is the process of nirvikalpa- or asamprajñāta-samādhi infusing permanently into all other states of consciousness like oil spreading over the surface of water. In his descriptions of these inner states, Swāmī Rāma explained that yoga-nidrā brings one very close to samādhi, since deep sleep and samādhi are very similar, samādhi being conscious and deep sleep being, usually, unconscious. Yoga-nidrā gradually wears away the boundary between them so that, as Lakshmanjoo explains, based on Kṣemarāja’s commentary on Śiva-sutras I.11 ([12], pp. 39–44), most people’s first experience of samādhi occurs in sleep rather than in meditation.

5. Technique and preparation for yoga-nidrā

The “technique” for yoga-nidrā itself is quite simple: from the activated suṣumnā-ṇāḍī, sink your awareness into a silent cave in the heart (anāhata) cakra with no thought and only the awareness of breath/prāṇa. Most people cannot achieve the required absence of distracting thoughts as a result of unresolved emotional conflicts that tend to be carried in their bodily tissues, their mind and their relationships. For them, it requires an effort to totally relax each layer (koṣa) of the body–mind: physical body (anna-maya), energy body (prāṇa-maya), lower mental/sensory body (mano-maya) and the higher mental body (vijñāna-maya). Hence the array of preparatory practices of various traditions [13, 14, 15]. It is important not to confuse these preparatory practices for the state of yoga-nidrā and, similarly, to confuse verbally facilitated relaxation with yoga-nidrā. The lifetime process of making the body–mind clear, pleasant and stable so that the body–mind can remain perpetually relaxed and concentrated is referred to by Patañjali (I.33) as citta-prasādana, “making the mind-field clear, pleasant and stable” [6]. This is the principal subject of the external limbs of yoga practice which prepare the body–mind to enter (and remain in) deep states of meditation [16].

So, for most people, a series of relaxation practices are necessary to accomplish this multi-level, preparatory relaxation. All of these various methods can work and none of them are a guarantee of reaching the state of yoga-nidrā. There is no way to compare the methods empirically because their success depends to a large degree on the quality of steady state relaxation of the subjects. The generic method taught by Swāmī Rāma ([2], pp. 186–191) for a general audience involves the following and takes this author about 90 min to complete when leading it with a group:

1. General progressive muscle relaxation. The more points of concentration, the deeper the relaxation is likely to be.

2. 61-point relaxation, often referred to as śavayātra, “the pilgrimage through the corpse,” where 61 marma points are visualized going through the body.

3. Śithali-karaṇa, a practice where breath/prāṇa is visualized sweeping down the body with exhalation and up the body with inhalation, stopping the flow at the toes (10 times), then the ankles (10 times), then the knees (10 times), then the perineum (5 times), then the navel center (5 times), then the heart center (5 times), then the throat center (5 times), then between the eyebrow center and the spot where the nosebridge meets the upper lip (5 times), then from the crown of the head to the eyebrow center (5 times) and then down the body from crown to throat center, crown to heart center and so forth in reverse order, down to the toes.

4. Five breaths through the eyebrow center (controls the waking state), five breaths through the throat center (controls he dream state) and five breaths through the heart center (controls deep sleep).

5. Then awareness is taken into the heart center cave with no thought other than the awareness of breath. Remain for up to 10 minutes and then exit gently and gradually, maintaining breath awareness. This limitation of ten minutes was never directly explained by Swāmī Rāma. According to Swāmī Veda Bhāratī ([3], p. 61), practicing longer than ten minutes conditions the mind to states that are in the sub-delta range of brain waves, 0–0.5 Hz, a coma-like state which is the bhava-pratyaya state described in Yoga-sutra I.19, which, contrary to some interpreters of the sutra, is not a high state of samādhi.

Swāmī Veda taught a number of abbreviated methods designed for those with deeper steady-state relaxation, none of which have been published. He taught these on an individual basis. Other teachers have assembled differing sets of preparatory practices, the most popular of which are the ones propounded by Swāmī Satyānanda Saraswatī of the Bihar School of Yoga [13, 14, 15] Once again, any of these sets of preliminaries can prepare a practitioner to enter yoga-nidrā, although none of them is a guarantee of reaching that state.

6. Health benefits of yoga-nidrā

The health benefits of yoga-nidrā generally parallel the many benefits of ordinary sleep. Sleep science has demonstrated that across almost all disease categories, sleep has the largest overall positive effect size as a therapy [17]. Most of these cluster around strengthening a person’s parasympathetic relaxation system, the rest, relax and restore system. Modern life easily exploits the vigilant bias of our nervous system towards the need to respond quickly to threats via the largely sympathetic autonomic stress response systems (so-called “fight, flee or freeze”). Yoga-nidrā greatly strengthens a person’s ability to maintain steady-state relaxation.

Pandi-Perumal et al. [9] have reviewed the empirical studies of therapeutic benefits in some detail. This is a summary of their review:

Several studies demonstrated significant improvement in the ability to maintain a state of relaxation along with significant reductions in mild to moderate anxiety and depression. This was measured both by standardized test instruments for anxiety and depression as well as by electromyography. It was not as effective with severe anxiety and depression. In a study with adolescents self-reporting physical or emotional abuse, yoga-nidrā was effective in improving the subjects’ performance on a mental health test battery.

In a cohort of wrestlers, yoga-nidrā helped the subjects improve their reaction times while wrestling by improving their focus and concentration.

In terms of psychosomatic disorders, a group of subjects suffering from tension headaches were carefully evaluated medically and then separated into experimental groups that received biofeedback treatment with electromyography or yoga-nidrā. The yoga-nidrā group experienced about the same degree of relief as the biofeedback group.

A cohort of 75 female subjects with menstrual irregularities achieved a substantial rebalancing of reproductive hormones with yoga-nidrā compared to a similar sized control group. This result is consistent with the role of ordinary sleep in balancing many different hormonal systems.

Positron emission tomography (P.E.T. scan) studies by [18] demonstrated a 65% increase in endogenous dopamine levels in the ventral striatum of subjects Lou et al. [19].

One study of pain responses to colonoscopy carried out with music therapy and with yoga-nidrā compared a control group who received no intervention to groups who received music therapy and yoga-nidrā. They found that both pain and insertion difficulty were significantly less in the yoga-nidrā and the music therapy groups compared to controls. Use of yoga-nidrā with pain treatment appears to be an important future field of study.

An array of studies of cardiovascular and inflammatory conditions demonstrated the expected reductions in blood pressure and increases in heart rate variability, but also showed significant improvements in erythrocyte sedimentation rate, an indicator of acute inflammation, as well as increases in both hemoglobin and overall leukocyte count, both of which support better immune function. When yoga-nidrā was studied against other yoga practices (prāṇāyāma, āsana, meditation) it produced significantly better results.

A study of type II diabetics using yoga-nidrā in addition to oral hypoglycemic medications compared to a group using the medications alone showed considerable additional reductions in several blood sugar measurements. This is consistent with the well-known role of sleep in the regulation of blood sugar, appetite and satiety.

Several studies demonstrated significant improvements in most sleep parameters, including significant reductions in salivary cortisol levels, an indicator of stress. Datta et al. [20] reported such positive results that they concluded yoga-nidrā alone may be sufficient to cure chronic insomnia.

One contemporary form of yoga-nidrā, the iRest protocol developed by Richard Miller [15], has shown considerable promise as a therapy for post-traumatic stress disorder. It is the subject of major multicenter trial for use with military veterans by the Veterans Administration of the United States.

One effect cited by some yoga teachers is that one hour of yoga-nidrā is the equivalent of up to four hours of ordinary sleep. This kind of sleep dosage effect has never been established empirically, although anecdotal evidence suggests that the practice, done over long periods of time, does gradually reduce one’s natural appetite for sleep (what sleep scientists refer to as “sleep debt,” the tiredness we feel when our body is ready to sleep).

Given the example of Swāmī Veda Bhāratī, who appeared to have remained in yoga-nidrā most of the time in his later years, and who lived cheerfully and actively while experiencing very severe type I diabetes, severe cardiovascular disease and chronic pain, it would seem that yoga-nidrā holds much promise as an intervention in a broad range of health problems. Like clinical hypnosis, it is likely to prove useful with psycho-somatic conditions and auto-immune diseases, which are almost always associated with elevated levels of arousal and physiological stress.

7. Conclusion

Although it has existed as a practice in the caves of the Himalayas for centuries, yoga-nidrā has been widely available in the larger world for 54 years. It holds very significant potential benefits as a component in treatment utilizing yoga therapy for a broad range of conditions. In fact, this author would argue that it focuses and potentiates the already powerful healing properties of ordinary sleep. As both research investigation and clinical utilization of yoga-nidrā proceed, it’s skillful use necessitates that we remember that yoga-nidrā is a state of mind which can be reached by any of the preparatory relaxation practices available today. Success in its performance requires repeated practice over an extended period of time in the context of a yogic life which gradually brings the practitioner to a continual state of profound and mindful relaxation and regeneration.

Acknowledgments

Acknowledgement is due to Swāmī Rāma of the Himālayas and Swāmī Veda Bhāratī (Uṣarbudh Ārya D.Litt.) for tangible and intangible guidance in yoga and specifically in yoga-nidrā over 52 years. Their interest not only in the practice but also in the rigorous scientific investigation of the practice and its benefits inspired this author to re-explore neuroscience after a career as a psychotherapist and professor. Their effort left us all an enduring gift of healing for humanity.

Conflicts of interest

There are no conflicts of interest.