https://en.wikipedia.org/wiki/Sleep_paralysis
http://www.wisegeek.org/what-are-hypnopompic-hallucinations.htm
https://en.wikipedia.org/wiki/Hypnagogia
https://en.wikipedia.org/wiki/Hallucination
http://www.csicop.org/si/show/oliver_sacks_on_hallucinations/
This is not to poo poo your experiences, it is to encourage you to find the answer.