Hi El,
I have experienced sleep paralysis and strange noises at the onset of sleep. Often I think I heard something crash to the floor and wake up startled. I also was plagued for many years with hypnagogic hallucinations, that is when you partially waken but not completely, and your dream takes place right in front of your eyes in your own bedroom. I have seen some pretty scarey stuff in my bedroom! This began for me when I was a teenager and continued until I was in my early thirties, now it only happens to me rarely, usually if I am extremely over-tired.
I went to a sleep clinic once and they explained my problem to me. I was told that some people will go direstly into REM sleep right after they nod off. Most folks are asleep for a while before this happens. When you are in REM you are dreaming and when you are dreaming your brain turns off your ability to move. This is to protect the dreamer from thrashing about or perhaps even jumping out of bed. Can you imagine dreaming you were being chased and waken to realize that you are running down the road.
So this paralysis is actually a good thing, although it is scarey when you can't move, I know.
I was asked at this clinic if I dream when I nap, which I do, they said this was indicative of someone who goes directly into REM. They told me I do not have narcolepsy. You might ease your fears by talking to your doctor.
I hope this helps, atleast you know you're not alone. Good luck.