The act in which someone, often at a work station, is so finely on the cusp of sleep yet in a mental state of readiness.
Guy no. 1: What can you see on that monitor?
Guy no.2: What? ...Oh yep, that's not good, let's go sort that out.
Guy no.1: Dude were you just sleeping?
Guy no.2: Nope I was sleeping awake, it's different.