The man is a blind midget, the shortest one in the circus. Another midget, jealous because he's not as short, has been sawing small pieces off of the first one's cane every night, so that every day he thinks he's taller. Since his only income is from being a circus midget, he decides to kill himself when he gets too tall.
or...
Instead of sawing pieces off of the midget's cane, someone has sawed the legs off of his bed. He wakes up, stands up, and thinks he's grown during the night!!!