When drivers are deprived of sleep there are definite behavioral changes, such as slower responses to stimuli and a reduced ability to concentrate, but people’s self-awareness of these changes is poor.
Situation
When drivers are sleep deprived, there are definite behavioral changes (making them worse drivers), but drivers' self-awareness of these changes is poor.
Most drivers think they can tell when they are about to fall asleep, but they can't.
Principle
Even though you're worse than normal, you can't recognize it? People are unaware that they are on the brink of danger / doing something dangerous?
Goal
Let's get rid of four answers that we can match up with the vibe of the principle we extracted.