Snowth, I've never heard of twilight sleep, but what you described sounds like sleep paralysis. I had a bad case of it last week, so it's still kinda fresh in my mind... Usually they happen either in the middle of or in between dreams, and just consist of me having vertigo (Sp?), for a few seconds. This one though happened just before I woke up. My arms and legs felt tingly, like when they've fallen asleep and are just starting to wake up, and it's like a very intense tickling sensation bordering on pain. There was this voice in my head, (not a real voice but more like what you would imagine if you were imagining dialog in your mind), telling me to scream, but it was kind of in a taunting way, like a killer in a movie might. At the same time, being at least partly awake, I knew that screaming would be a bad idea since I wasn't in any real danger and screaming would alarm the other people in the house. Eventually I tried to scream anyway, and as is tipical in such instances, nothing, or at least nothing substantial, came out. Naturally I couldn't move throughout this whole thing, which seemed to last a few minutes. Anyway, now that I've gotten that off my chest, lol, I think I read somewhere that it's caused by part of the brain waking up too soon or something, and the parts that are asleep and awake sort of clashing with each other.
I've also had that happen where I've woken up, gone to the bathroom or something, still felt a bit tired and gone to bed, only to have a horrible nightmare. The last time was so bad I swore I'd never do it again! There've been times since when I've wanted to go back to bed, checked the time, and suddenly felt much more awake... I think that the reason we tend to have nightmares often during the day is that it's not normal to sleep in the daytime. So when we do, it's our brain reacting to the idea that something's not right. On a related note, I think it was on
www.dreammoods.com
that I read that most nightmares tend to happen in the early morning, shortly before we wake up. Maybe this is because they're usually dealing with some issue that we desperately need to be paying attention to, and are therefore more important for us to remember?
Sleep and dreams are also topics that I'm extremely interested in!