Written using the Freewrite Writing Prompt by 
...
"You look dreadful," Bill said.
"Thanks."
"Black rims around your eyes. No colour in your face."
"Again," I said. "Thanks for pointing it out."
"You ill?"
"No," I paused, trying to decide if it was worth telling Bill about the endless nights I spend in bed eyes open examining the darkness of the room looking for what lurks in the shadows of my mind. "Just a bit of trouble sleeping."
Bill nodded.
"Guilty conscience? he asked.
I snapped my head up and looked him in the eye.
Does he know?
"What do you mean?"
Bill laughed.
"Nothing. Just something my mother used to say if I couldn't sleep."
I forced a laugh and followed it with a smile.
"No, nothing like that. Probably just worried about work."
Bill nodded and then coughed.
"Shall we get a move on, then?"
...