Yoga Nidra is a meditative state between sleeping and wakefulness. It promotes a really profound state of relaxation.

Here is a podcast with Richard Miller who is a teacher and scholar on Yoga Therapy and has developed a Yoga Nidra protocol (on iRest). I recommend it, it’s really well done.

https://podcasts.apple.com/us/podcast/5-exploring-irest-and-yoga-nidra-richard-miller/id1730976783?i=1000649099073

Here is a link to an audio-recording of a short Yoga Nidra practice that you can try.

Here are other teachers who specialize in this practice: