Is it normal that i can't sleep?

I'm fourteen and I can't sleep. Hardly ever. It doesn't effect/affect my performance in school, sports, or social activities. I don't get tired and even when I do get tired I can't sleep. I can fall asleep at four a.m. After twenty hours of no sleep and wake up an hour later and be ready to make breakfast and get ready. I don't know what to call it... Is it insomnia? Is it a sleep disorder of some other sort? Also, whenever I sleep more than five hours at a time I wake up feeling like I'm going to die and that I'm falling and I can't breathe. I feel like someone's on top of me with a rag down my throat and a knife slowly pressing harder on my neck and I can't move my limbs. This lasts for about two minutes. I don't breathe the whole two minutes. I can tell when this will happen because I will be dreaming and I will die in my dream, always a different way, always a different time period, but I always feel the death occurring. Please help i have no clue what to do, it scares me to no end...