One strange thing KA Applegate does is use sentence fragments or single words a lot. Like this. Falling. Falling. And somehow that actually makes you scarier, because when you're scared, your mind really does speed up like that and rush your thoughts as quick as possible because there isn't time to think.
But it's bad grammar. I can remember trying to copy that on my elementary school papers, and getting marked down for it. I guess when you're a writer, it's okay to break the rules as long as you do it right.