A Question about Wild/SP

So... two nights ago, I went to sleep doing autosuggestion, and without knowing it, I lay still there for long enough to do SP or something. I felt heavy, but I think I could've moved if I wanted to, so it probably wasn't SP, but my pulse went really fast for a couple minutes. I thought I was entering a lucid dream, but then my pulse just slowed down and after ten minutes nothing happened so I went to sleep.

Any ideas on what this was?

EDIT: This was my first time trying to WILD (even if it was accidental) and it only took about 5 minutes of lying still. I was a bit tired though.

Happens to me aswell. I guess its the first stages of sleep paralysis but im not sure, just letting you know you aren't alone.

thanks, appreciate it!