Electricity in my head...?

I was wondering if anyone knows what this is...
It only happened to me once, about a year ago, but a friend of mine used to get the same thing all the time.
I've had a bit of a look around and it sounds a little bit like some people's description of sleep paralysis, but I've always been curious about its cause:

I had woken from a dream and could feel myself in my bed, but I felt this electricity building in my head. The sound and feeling grew stronger and more unbearable but I couldn't move my body or open my eyes to make it stop. It lasted for at least a minute, and the pressure inside my head seemed to build and make it more difficult for me to move. It was excruciatingly uncomfortable and I was relieved when it finally stopped.

1. What may have caused this?

2. Does it have any use, if it happens again?

Definitely sounds like sleep paralysis. Holding your breath quickly takes you out of it, since your brain is trying to breathe for you during SP.