Yoga nidra is a practice introduced by Swami Satyananda Saraswati that is neither sleep nor concentration. It helps open the inner chambers of the mind. The practice involves rotating awareness through different parts of the body, experiencing sensations like heaviness and lightness, visualizing objects, and awareness of the chakras. It concludes with repeating the initial resolve and slowly opening the eyes. Yoga nidra can help with psychological disorders, insomnia, pain relief, and some cardiovascular and psychosomatic conditions.