The kind of involuntary sleep you experience when you're really tired and trying to stay awake in a monotonous situation, like a class lecture. One minute you're propping your head in your hand, trying to pay attention, when all of a sudden you're out -- at least until your elbow slips sideways or your head falls forward, jarring you back to attention. Caused by a consistent lack of sleep over several days. Often the cause of car accidents, when the driver nods off during long hauls.

When you eat dirt for the first time and leave your family to build a shack in the woods