Is it normal i'm this paranoid?

I can't take a shower while I'm home alone - or even when someone's in the next room, but sleeping. When I take a shower and no one's around, I almost ALWAYS have violent thoughts about wild animals attacking me or someone torturing me and/or killing me. Sometimes I freak out and leave the shower early, because it disturbs me so much.

And it's hard for me to sleep, when everyone else already fell asleep and I feel alone. I usually have to turn the lights on at that point. I could be lying there trying to fall asleep - but that could easily be interrupted by me imagining a bunch of huge metal spikes or stone crushing my body, or being burned with fire or brands, being cut open, being eaten alive by a hyena or lion, etc.

I could be subjected to violent thoughts getting in the way at any time, though. I remember being in class and squirming in my seat, because I was thinking about somebody crushing my bones with stones/boulders to paralyze me.

Sometimes I hate not having my back against the wall, because I think of someone coming behind me snapping my neck or strangling me to death.

I could DEFINITELY go on and on, but you should get the point by now.