Hummingbirds burn incredible amounts of energy because of how fast they flap their wings. If they don't find nourishment fast, they can die from exhaustion. Why they don't stop and rest is nature's doing. Also, they are like flies & bees, in that, by instinct, they fly upward. You can catch flies & wasps & bees in a jar and turn it upside down and they won't fly downward to get out of the jar. The same with the hummingbirds but it's also possible that, if they saw light up near the ceiling, they'd naturally fly toward it.
