Thread: Very Strange, Scary - Please Help!

Hello; last night, I had a very strange experience and it terrified me - any help, information, or speculations would really be appreciated. (I'm open to any ideas you may have... I know when I google this I come up with alien abductions, hehe)

Last night, at around 2-3 in the morning, I woke up. I was lying there under the covers, just thinking about things and trying to get back to sleep, when all of a sudden there was this... jolt - almost like a small seizure. And this sounds crazy, and I don't know how to describe it, but it almost felt like a dimension-shift, like everything went flat. I don't even know what I mean by that - just that for an instant, everything was flat and strange. It lasted for a split second, and when it snapped back to normal I was lying in a different position and absolutely terrified.
I just remember clutching at the covers with my heart pounding; I was completely conscious and petrified. This went on for more than a half-hour - my heart just pounding so fast the entire time. I was sweating and just balled up under the covers, not wanting to move, just this really intense feeling of panic and fear over me - almost like an anxiety attack? Only I've had those, and this was different...
I was terrified of falling back asleep and it happening again, so I lay there for the longest time. Finally, I slipped back into sleep - dreams continued on like normal.

This really shook me up, so I'd really like to hear any theories on what it could be. When I told a friend about it the next day, I started crying o.o
I hadn't realized it'd affected me so much until then. So please, any help would be appreciated...
Someone suggested it was a sudden drop in blood pressure; he said he'd had that happen before during the day once, and experienced a similar feeling of confusion and almost a temporary "dimension shift".
Anyway, please help.
Thanks!