Stage One Sleep Disorder?

Hi, I was wondering if anyone had any information on the existance of any stage 1 sleep disorders. I've been having a problem in which one would describe as being similar to a sleep terror but it occurs in stage 1.

I think we've all had little episodes right before we fall asleep that makes us jump or shake. Although i'm not sure what you would call it, I think it's common becuase a lot of people know what i'm talking about when I describe it. Kinda like dreaming that you've falled off of a bike and act out right before you fall asleep.

However, my problem is different. I would have to generally describe it as this: I feel as if i'm consious during the transition of being awake and falling into sleep. I feel myself "go under" and i'm awake when it happens. At least this is the best way I can describe it. When it happens, I scream at the top of my lungs and it only lasts for a second or two. I guess I also feel as if i'm out of breath when it occurs. This could be becuase I just got through screaming. I'm fine after it occurs and I really don't rememeber what causes me to scream. I can only assume that it's scarey at the time. There is no dreaming going on either as I have no memorable visions or feelings. After it occurs, I remain awake and try to fall asleep again only to go through the same episode at least a handfull of times more until I finally do fall asleep.

I feel bad becuase this startles my fiance and it cant be good for me. It must really suck to go to bed with someone who you know is going to scream at the top of their lungs at any time. I cant image how frightening this is for my significant other. It seems to be amplified while under stress and happens occurs almost regularly.

Any help or links to others who've had similar experiences would greatly be appreciated.