This kind of practice is at least as early as yoga: https://en.wikipedia.org/wiki/Shavasana https://en.wikipedia.org/wiki/Shavasana https://en.wikipedia.org/wik

This kind of practice is at least as early as yoga: https://en.wikipedia.org/wiki/Shavasana https://en.wikipedia.org/wiki/Shavasana https://en.wikipedia.org/wiki/Yoga_nidra https://en.wikipedia.org/wiki/Yoga_nidra