Hi, I’ve had this strange state a couple of times at the end of WBTB. It has happened when I have layed still for a long time. I’m on the edge of falling asleep, my thoughts are strong and dream like. Then I feel my mind crossing a border, it’s like I fall asleep while being awake. Usually my leg starts to rise by itself, or at least that’s what I feel. I feel this odd pressure in my head and may hear some sounds. It’s a sensitive state, I think I can move myself and end it if I want to. Once a dream started to form in front of me. I know about WILD, but haven’t read anything about mind crossing a border. It it just some ordinary phase I haven’t read about?
Yeah, you were experiencing SP and entering into dream from waking state…
I know what you’re talking about with your leg rising by itself. It’s just a feeling. Although one can’t be 100% sure. Once I moved my hand and arm involuntarily, but it snapped me awake. I also know what you mean by “crossing a border”. I have discerned what I call thresholds, two in all, because after the second threshold my breathing starts to become strange and I freak out and break out of it, so I don’t know if there are more. I am not paralysed during this state. It only happens if I try to WILD when first going to bed, and it takes a long time to get there. There can be other strange hallucinations as well. I think that fits pretty much what you described.
I can break out of it just by moving so it does not sounds like SP, but it could be that it is just the beginning of it.
The sounds you hear are HS. They’re quite realistic and vivid, but aren’t real.
Yes… in sleep paralysis I couldn’t be able to move if I have understood it right. But on the other hand this is all so subjective stuff. Very interesting 
I’ve had a feeling like that once. But I’ve never experienced full SP, which bothers me. I always get this weird, numb feeling all over my body, but nothing more. No mattet how long I lay still. Meh, whatever, practise makes perfect!
But yeah, I/we must just learn to cross that border. Good luck!