Yoga nidra or yogic sleep is a state of consciousness between waking and sleeping, like the "going-to-sleep" stage. It 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 instructions. This state of consciousness (yoga nidra) is different to meditation in which concentration on a single focus is required. In yoga nidra the practitioner remains in a state where his senses are internalized, that is, withdrawn, and only the hearing still connects to the instructions. Yoga nidra is among the deepest possible states of relaxation while still maintaining full consciousness.

The practice of yoga nidra 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 (PTSD).
They say one hour of yoga nidra is the same as 4 hours of sleep.