Question about my dreams?

I've had a lot of nightmares since i can remember....i've been shot at,stabbed....my family has gotten hurt,i have nightmares about zombies,snakes,wolves,vampires,i've woken up crying numerous times after somebody close to me gets hurt...i watch scary movies very seldom,there are times when i wake up so scared that i'm afraid to move in the bed for 20min until i get comfortable again...many times when i'm dreaming i'm not myself...in my last dream like that i was a chinese guy...and i'm a white female...there have also been some weird ones like i have forgotten to set my alarm clock and somebody in my dream tells me to wake up exactly when i'm supposed to,which is pretty cool:)and something told me in my dream that something terrible has happened at the same time when a friend of mine died of leukemia:(why am i seeing so many nightmares?why am i not myself?and how do i know what time it is?