What goes on in a head during a dream?

It can be a sweet dream or a nightmare,

In a nightmare your body will want to scream,

Horrible dark dreams that will leave a tear,

Darkness appears and feels like it will stay,

Devouring you whole with no real escape,

There is no escape even if you pray,

Your mind seems as though it is in bad shape,

Sleeping has been the worst part of your life,

Until you finally take control back,

The darkness is cut away with the knife,

The dream is becoming lighter than black,

From the dark you keep on trying to flee,

Until you feel as though you can be free