All that I am afraid of

I look out through the bars.  
I've been a prisoner here for as long as I can remember.  
By day I stare out the bars with thoughts of hope of leaving it all behind,
by night there's nothing but darkness and being chased by the nightmares that haunt my very being.  
Where am I you ask?  
Well my mind of course.  
I can never leave for its a part of me you see.  
I am a prisoner of my mind.  
All that I am afraid of is looking back at me through the bars....its me.