It would help to read from one of the modern developers of the technique as well as people who have used it for learning.
Swami Satyananda Saraswati founded the Bihar School of Yoga, and his version of yoga nidra is one of the most well-known in the West. His book goes over the details for learning boosts:
https://www.amazon.com/Nidra-Re-print-Swami-Satyananda-Saraswati/dp/8185787123
That being said, Devatma, who has a YouTube channel called Tripura Mandala and is trained in the Satyananda tradition, is experimenting with using yoga nidra to teach. (
https://www.youtube.com/watch?v=3f1GdJPaxgw )
Separately, Swami Veda Bharati (
https://www.amazon.com/Experiments-Yoga-Nidra-Swami-Bharati-ebook/dp/B00Y4X6XUU/ref=sr_1_1?dchild=1&keywords=nidra+veda&qid=1609888930&sr=8-1 ) recounts how he used the version from Swami Rama, which is one of the methods most focused on achieving conscious, deep sleep quickly in a "pure" way, to learn languages at an accelerated rate, but he didn't provide a refined systematic approach since it was something he picked up on his own from a young age. Here's what he said in other sources:
http://www.ahymsin.org/docs2/News/1407Jul/03.html
"Mastering Yoga Nidra
by Swami Veda Bharati
Many people write me asking if they can learn a language or complex mathematics in a very short period of time by applying Yoga Nidra. Here is my answer.
Yoga Nidra is not quite that much of a magic. One still has to study a subject in the regular way, then go into the Yoga Nidra state. Without disturbing the rest of the mental field, select the topic to be reviewed. The images or words and the topic come popping up in a proper sequence. One simply observes that. It is a difficult process to learn and even more difficult is to do conscious recall of the imagery that had emerged from the unconscious, when one comes out of that exercise.
This is easily described but not easily learnt.
It is difficult enough for people to go into pure Yoga Nidra and then more difficult is to selectively make a certain topic emerge from the reservoir of the unconscious into which it was earlier sent into storage while learning consciously.
So here are the steps:
Mastering pure Yoga Nidra
Conscious learning in a very relaxed state of body and mind so that the subject studied, read or heard sinks down into the unconscious.
Going into pure Yoga Nidra
Very gently, very very gently, inviting a select topic to emerge from the unconscious into the field of the Yoga Nidra mind.
Observing the images, words or (if you are learning music or have learned a language by audio) sounds, as they appear in the Yoga Nidra field; caution – the rest of the field must not be disturbed. Let the ripples in the calm lake remain confined to where the ripples are supposed to remain.
You will know when the desired image has played itself out.
Lying there conscious and relaxed
Doing a conscious recall of the same ‘audio’ or ‘video’ that was played out from the unconscious mind.
Get up and make conscious notes of what you have learned.
To reproduce it for a lecture, or using a language, or writing an exam, test or essay, put the mind in a relaxed state and not struggle to remember.
This involves a mastery of conscious mind, Yoga Nidra, area of the knowledge storage in the unconscious and finding channels of communicating among these layers.
I never learned how. I was never given a lesson except in the basic exercises leading to Yoga Nidra.
I have been using it from childhood, from the initiation into Yoga Nidra proper from the Guru and from what I have been doing (a) to learn and (b) to discover new knowledge. I am only giving a description of the processes I undergo.
We could try to do this in a workshop on a very rudimentary basis. Some lucky ones will catch it.
My own emphasis remains on pure meditation and pure Yoga Nidra. I do not teach curing headaches or learning languages. My shukla, shuddha-vidya goals are very clear to me.
I am now not going to open a language school in New York or Hollywood to speak French for French movies! I will not train my teachers to do that either."
So, yeah, that's an area that needs to be further researched and developed to teach others how to do it. If you want the pure Rama yoga nidra scripts, I can send you links where you can get it.
For yoga nidras I have personally used, here's a playlist:
https://www.youtube.com/playlist?list=PLqEWXVGDmfKRdbYmnV4hz2GRaqTQ3VrNp