In more detail:
I dreamt a dream in a dream (I don't recall what the inner dream was), and woke up into my first dream. In there, I had just woken up, the light from the outside seeping through the curtains was whitish-gray, and I didn't get up. My eyes fully opened, but before I knew it, a random man wearing a black mask like bank robbers do, came out of nowhere from behind me, grabbed my chest with his left hand, then stabbed me in the chest with a knife. When I woke from this dream, I got up extremely quickly, and without thinking of anything, my hand grabbed my chest where I was stabbed. I immediatly looked at where the assassin came from (which, weirdly, was my closet). The only thoughts that came to my mind where;
-What just happened?
-Was that just a dream?
-My heart's beating too fast.
-It's 5 in the morning!?!?!?
-This would happen a on a school say...

I just want to know if this is common and if it has any meaning about anything in my life.