Hidden me

I keep myself behind a wall,
I never will let it fall.
I've tried so hard to keep quiet,
Secrets are in my daily diet.
I keep myself in a hole,
And I've grown dull.
Theres a beast inside my mind,
And to it, they're blind.
I can't let them know,
This secret is about to make me blow.
I'm in a nightmare,
But I don't care,
Because I rather hear screams,
Than be stuck inside of sweet dreams.
I keep on a smile, being a tiny spark,
So they don't know my mind is completely dark.