It's solved in a much nicer way in modern vehicles. Where they detect # of line crossings (dozing makes you more prone to cross the lines on the road), and how

It's solved in a much nicer way in modern vehicles. Where they detect # of line crossings (dozing makes you more prone to cross the lines on the road), and how often and for how long your eyes are shut when blinking. Together they indicate tiredness, and can recommend that you take a break. Atleast that's how I remember it working on Mercedes cars