When you're sleepy, very sleepy, you are going to collapse. Imagine the feeling when you're doing something like driving. It makes me shudder, and the thought goes through my mind when I'm off to work at odd hours of the moring. (And then there's the nightcap crowd, and that's a whole other story.)
"Sleepiness is stronger than you" is the tag line of this Thai Health promotion. I saw it on the advertising blog We'll Be Right Back.