I didn't want the problem of sleeping on trollies to be too obvious in my work, I wanted to leave room for interpretation, and I wanted a metaphor to be used to say what I wanted to say.  I wasn't sure how to do this so I came across an artist/activist called Hank Willis Thomas who's great at displaying hidden meanings through visual metaphors as well as not making his message overly obvious.  Here's some of his work.

By looking at these, I thought of combining the trolley with the characteristics of an iron maiden which is a medieval torture device.  I used this as a metaphor for discomfort and suffering.