Yoga nidra facet of yoga
Yoga nidra (Sanskrit: योग निद्रा, yoga nidrā) or yogic sleep in modern usage is a state of consciousness between waking and sleeping, typically induced by a guided meditation. 
A state called yoga nidra is mentioned in the Upanishads and the Mahabharata, while a goddess named Yoganidrā appears in the Devīmāhātmya. Yoga nidra is linked to meditation in Shaiva and Buddhist tantras, while some medieval hatha yoga texts use "yoganidra" as a synonym for the deep meditative state of samadhi. These texts however offer no precedent for the modern technique of guided meditation. That derives from 19th and 20th century Western "proprioceptive relaxation" as described by practitioners such as Annie Payson Call and Edmund Jacobson.
The modern form of the technique, pioneered by Dennis Boyes in 1973, made widely known by Satyananda Saraswati in 1976, and then by Swami Rama, Richard Miller, and others has spread worldwide. It is applied by the US Army to assist soldiers to recover from post-traumatic stress disorder. There is limited scientific evidence that the technique helps relieve stress.Swami Rama
Swami Rama taught a form of yoga nidra (in a broad sense) which involves an exercise called shavayatra, "inner pilgrimage [through the body]", which directs the attention around "61 sacred points of the body" during relaxation in shavasana, corpse pose. A second exercise, shithali karana, is said to induce "a very deep state of relaxation", and is described as a preliminary for yoga nidra (in a narrow sense). It too is performed in shavasana, involving exhalations imagined as directed from the crown of the head to different points around the body, each repeated 5 or 10 times. The yoga nidra exercise itself involves directed breathing lying on the left side, then the right side, then in shavasana. When in shavasana, the attention is directed in turn to the eyebrow, throat, and heart centres or chakras.
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