Well, when I went to bed at 1:30 after playing Locomotion for 3 hours, I naturally switched off all the lights downstairs first. Thus, when I walked upstairs in the pitch darkness, I was unable to see the pile of towels and sheets that my wife had placed as a booby trap, and only narrowly avoided falling to my death by flailing around blindly and grabbing hold of the bannister just in time.
That's why the top of the pile there in the picture is a bit mussed up.