I have experienced sleep paralysis, and it is disturbing, yes. But I really think that it happens when your mind is in a stage of sleep where we are shut down from movement, and may be in "deep sleep". I think it is possible to maybe hear a sound and be consciously awake but stuck in the deep paralysis of deep sleep physically.

So I think it can be medically explained. As we continue learning about the brain we will have a better understanding of this. We are gaining a lot of knowledge of the brain with fairly new technology. We have a lot to learn yet about the human brain.
It is an amazing thing.

Open Eyes