My biggest resource to date has been Jana Roemer, a teacher and guide of Yoga Nidra.

Cited Sources on this website

1. "Radiant Rest - Yoga Nidra for Deep Relaxation & Awakened Clarity" by Tracee Stanley
2. "Neuroscience - Exploring the Brain" by Mark F. Bear, Barry W. Connors, Michael A Paradiso third edition
3. "Becoming Supernatural" by Dr. Joe Dispenza
4. "Why We Sleep" by Matthew Walker, PhD
5. https://en.wikipedia.org/wiki/Kosha
6. https://www.ananda.org/yogapedia/turiya/