Please help me find the key...!

Recently I've started having horrific nightmares... weird, violent stuff although I don't have a weird, violent life. (Could this be a reason?) Last night I dreamed I was watching a guy being tortured. Someone took a knife and sliced him horizontally across the face - slicing his eyeballs open. He screamed as someone else pulled his (now broken) eyes out of his head. I woke up.

Where does this come from?? I'm pretty sure I've never seen anything on tv, or read anything, where this happens. Yet I could see it all happening in perfect detail... the way his eyes oozed... bleaugh.

Another time I dreamed I was walking around a crime scene with a forensic expert who was explaining what had happened to the murdered girl. As he hypothesised I could see the things happening to this girl - her skin being peeled back, her hands tied to the chair...

I can't understand how my subconscious can create such vivid images and bizarre storylines. I've always known I have a vivid imagination, but this is taking things too far! I'm actually a bit freaked out as to why my brain is capable of creating this stuff. Now when I tell my boyfriend what happened in my latest night-scare he raises his eyebrows and says "hmm. untapped depths." Can your subconscious just string a few ideas together (knife, boy, eye) and create a scenario out of interest? Or was I a serial killer / torturer in a former life?!

Does anyone know where nightmares come from? Has anyone else had crazy nightmares?! Tell me I'm not a freak! :(