Demon at the Top of the Stairs

When I was about 5 or 6, I remember having to walk up the dark staircase of my parents' house to go to bed at night.  There was a window at the top of the stairs that caught ambient light reflections and once I thought I saw a face.  Over time, I became convinced that a devil was watching me climb the stairs, waiting for me to get into my bed.  I was never brave enough to look directly at the window, I kept my head straight down, and bolted from the top of the landing to my bedroom door, heart pounding with fear.   It's so strange to me that we are able to scare ourselves so badly with nothing other than our own imagination.