My fearsome friend

This terror washes over me.
I do not know the source.
I struggle to protect myself, 
I let it run its course. 
I wish now that I could return
To time before this fear, 
But I cannot pull myself away
When it would draw me near. 
It comes to me at night
Before I can drift off to sleep.
As I release my daily cares 
Inside my mind it creeps. 
Perhaps I cannot vanquish 
Or escape its piercing gaze. 
Perhaps I must embrace it: 
My companion in these darkened days.