When I usually go to sleep I undergo a series of repeatable phases each night, each of them fairly easy to remember. First I will lay in bed for a while without being tired, then I will turn onto my side or stomach and lay there for a while, then I will think random thoughts as I become tired (such as "1...2...3...applesauce" and "banana stickers" and so forth). However it is around this point when I begin to count from 1 to 100, twice. I will then stretch my body to crack the tightened muscles, and begin to recognize my dropping awareness. I will then continue thinking about nonsense until my vision begins to adjust and everything becomes darker.

Next thing I know I will almost instantly lose my short-term memory and it becomes almost impossible to keep my flow of thoughts on one topic for what seems a minute to me. I will also begin to experience twitches in the muscles of my body, usually at my fingers and/or legs. I will keep telling myself not to fall asleep or to stay awake for a short period of time, but eventually I will lose consciousness. Now here's the freaky part:

When I lose consciousness, the NEXT thing I remember (and this has been repeating for at least three nights now) is waking up while feeling all the muscles in my body twitching rapidly. It's almost as if I feel a vibration, but it feels more violent and irregular than that. As soon as I wake up though, the twitching stops and I look at the clock to see I've had an hour or so in my lapse of consciousness. When I close my eyes again I see random but colorful lights, and as I focus on them I begin to fall asleep again. I haven't stayed conscious up to this point yet, but I'll make it my priority tonight to do so.

My question is, can anybody give me an explanation for what that twitching and bright lights are? It isn't a one-time phenomenon, apparently, so I know there must be some explanation for it.