Lyric discussion by eOgas 

Cover art for Sleepwalkers lyrics by They Might Be Giants

I think this song is about how people get into a routine and do the same thing day after day without thinking. They are, in essence, sleepwalking. The song is sung from the perspective of someone that has either broken from the routine or was never entrapped in this sleeplike state at all.

"see them moving down the road": I imagine a bunch of people in their cars during rush hour "their arms held out ahead": to hold the steering wheel.

The narrator ponders what would happen if you would "wake" them AKA point out the trite nature of their actions to them. Perhaps they will say "Man, what a waste of my life", but the narrator is quick to remind us not to wake them, maybe because the narrator wants to keep the exclusive quality of consciousness. Either that, or it's just about people sleepwalking.