Sleep Paralysis

Has anyone ever experienced this phenomenon? I'm pretty sure I did early this morning before waking and it scared the shit out of me.

From the good people at WedMD:

"Sleep paralysis is a feeling of being conscious but unable to move. It occurs when a person passes between stages of wakefulness and sleep. During these transitions, you may be unable to move or speak for a few seconds up to a few minutes. Some people may also feel pressure or a sense of choking. Sleep paralysis may accompany other sleep disorders such as narcolepsy. Narcolepsy is an overpowering need to sleep caused by a problem with the brain's ability to regulate sleep."

I had a similar experience. I had a feeling of being conscious yet unable to move, mostly. For some reason I thought I was scratching my head and became a little freaked out when there was no sensation to the scratching. I believe now I was actually scratching the pillow underneath me, if that's even possible. I definitely had trouble breathing or at least I thought I did. It was like I couldn't catch my breath and I was convinced that I was suffering some kind of fatal medical condition. I mentally willed myself to breath or move to no avail for maybe a minute. Terror doesn't even begin to describe how I felt throughout this ordeal. Finally I was able to breath normally again and move. I got up off the sofa (my normal sleeping place) and relocated to my bed without any further incidents.

Since I don't have narcolepsy and this has never happened before I'm not really worried about it. Most likely, from the reading I've done, in my case it was probably from a lack of sleep or the alcohol I ingested last night. Still, it was a horrifying experience that I don't want repeated any time soon.

It's also interesting to note that previous, less medically advanced cultures, thought that sleep paralysis was the result of demons or the devil sitting on your chest. Modern scientists conclude that some reported alien abduction encounters and ghost encounters could simply be explained away as a sleep paralysis episode. Who knows, maybe I was possessed by the devil, something that a few people who know me wouldn't dispute! Interesting stuff.

So, dear reader, has this phenomenon happened to you and if so what was your experience?