Yoga nidra or yogic sleep is a state of consciousness between waking and sleeping, like the "going-to-sleep" stage, typically induced by a guided meditation. There is evidence that yoga nidra helps relieve stress. An ancient technique from India, it has now spread worldwide and is also being applied by the US Army to assist soldiers to recover from post-traumatic stress disorder.
Yoga nidra is a state in which the body is completely relaxed, and the practitioner becomes systematically and increasingly aware of the inner world by following a set of verbal instructions. This state of consciousness is different from meditation, in which concentration on a single focus is required. In yoga nidra the practitioner remains in a state of light withdrawal of the 5 senses with four senses internalised, that is, withdrawn, and only hearing still connects to any instructions given. The goals of both yogic paths, yoga nidra and meditation are the same, a state of meditative consciousness called samadhi. It is among the deepest possible states of relaxation while still maintaining full consciousness. In lucid dreaming, one is only, or mainly, cognizant of the dream environment, and has little or no awareness of one's actual environment. Yoga nidra results in conscious awareness of the deep sleep state, which is called prajna in the Mandukya Upanishad.
History
It is said that the history of yoga nidra is as old as yoga itself, as the first mention of yoga nidra is in the Upanishads. Lord Krishna is associated with yoga nidra in the epic Mahabharata:
Modern usage
In modern times, Satyananda Saraswati claimed to have experienced yoga nidra when he was living with his guru Sivananda Saraswati in Rishikesh. He began studying the tantric scriptures and, after practice, constructed a system of relaxation which he popularized in the mid-20th century. He explained yoga nidra as a state of mind between wakefulness and sleep that opened deep phases of the mind, suggesting a connection with the ancient tantric practice called nyasa, whereby Sanskritmantras are mentally placed within specific body parts, while meditating on each part. The form of practice taught by Satyananda includes eight stages. Satyananda used this technique, along with suggestion, on the child who was to become his successor, Niranjanananda Saraswati, from the age of four. He claims to have taught him several languages by this method. The Mindful Yoga teacher Anne Cushman states that "This body-sensing journey ... is one variation of the ancient practice of Yoga nidra... and of the body-scan technique commonly used in the Buddhist Vipassana tradition." The western pioneer of yoga as therapy, Richard Miller, has developed the use of Yoga nidra for rehabilitating soldiers in pain, using the Integrative Restoration methodology. Miller worked with Walter Reed Army Medical Center and the United States Department of Defense studying the efficacy of the approach. According to Yoga Journal, "Miller is responsible for bringing the practice to a remarkable variety of nontraditional settings" which includes "military bases and in veterans' clinics, homeless shelters, Montessori schools, Head Start programs, hospitals, hospices, chemical dependency centers, and jails." The iRest protocol was used with soldiers returning from Iraq and Afghanistan suffering from post-traumatic stress disorder. Based on this work, the Surgeon General of the United States Army endorsed Yoga Nidra as a complementary alternative medicine for chronic pain in 2010.
Scientific evidence
Yoga nidra meditation is associated with increased endogenous dopamine release in the ventral striatum of the brain. The reduced desire for action in the state is associated with the reduced flow of blood in parts of the brain connected with controlling actions, the prefrontal cortex, the cerebellum and the subcortex. Yoga nidra improves heart rate variability, a measure of balance in the autonomic nervous system, whether or not it is preceded by a session of hatha yoga asanas. The regular practice of yoga relaxation has been found to reduce tension and anxiety. The autonomic symptoms of high anxiety such as headache, giddiness, chest pain, palpitations, sweating and abdominal pain respond well. It has been used to help soldiers from war cope with posttraumatic stress disorder. A 2019 study suggests that yoga nidra can alleviate stress and improve self-esteem of university students.
