This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Yoga nidra is often described, including by its own teachers, as a state resembling sleep, but the distinction its practitioners draw is exact: it aims at deep bodily and mental rest while consciousness itself stays present, rather than the loss of awareness ordinary sleep involves. The practitioner lies still while attention is guided, by a teacher's voice or a recording, through a sequence, awareness of the body region by region, awareness of the breath, guided imagery, toward a threshold state some teachers compare to the hypnagogic state between waking and sleeping, where the body is fully relaxed but the mind remains, in the tradition's own description, a witness rather than an absence.
What the practice is not, and what accounts using casually with terms like nap or meditation-sleep obscure, is either ordinary sleep or seated concentration meditation. It requires no posture practice and no physical exertion, which is part of why it is taught in settings from yoga studios to hospitals and trauma therapy programs, but it is a specific, structured method with a beginning, a sequence and an end, taught by a guide, not an unstructured rest period. Contemporary clinical interest, in fields from sleep medicine to trauma treatment, has focused less on testing the tradition's own claims about consciousness during the state and more on whether the relaxation response it reliably produces has measurable value on its own terms, a narrower and more answerable question than what the state of consciousness it induces actually is.