This practice introduces us to rotation of consciousness around the body, a very key tactic of tantric perception which is simple but can become a key tactic to overcome the mind and enter into altered states for various purposes including implanting simple ideas like positive affirmations.
Nyasa part of Sri Vidya tantra (One of the biggest groups).
It implants dieties into the body at specific places along with mantras
EFT (Emotional Freedom Technique has similarities).
Use body sensations to plant positive affirmations
Divine Life Society publishes many tantric books
Swami Satyananda Saraswati wrote the book Nidra Yoga which he says has ALL the benefits of Nyasa without having the cultural constraints of language.
Nidra Yoga is usually done with a leader guiding the meditation
It comprises various stages including : Preparation, Relaxation, Resolve/Intention, Rotation of consciousness, Breathing, Image VIsulization, Resolve/Intention, Finish
Nidra yoga allows us to build up energy or to astral project or to evoke or just to make positive changes in our lives