Yoga Nidra is a simple yet profound technique, adapted by Swami Satyananda Saraswati from the traditional tantric practice of nyasa. This book explains the theory of Yoga Nidra in both yogic and scientific terms and includes transcribed lessons from classroom teaching. It also presents the multiple applications of this versatile technique, which has been used in deep relaxation, stress management and therapy, enhancing the learning process in education, harmonizing deeper unconscious forces, awakening inner potential, and also as a meditation technique. The book includes an extensive presentation of scientific research.