This is true, but the chance of an incident occurring during neither takeoff or landing, when both pilots happen to be asleep at the same time is fairly low. O

This is true, but the chance of an incident occurring during neither takeoff or landing, when both pilots happen to be asleep at the same time is fairly low. On the other hand, sleep deprivation (which as the article mentions, can be far worse than being legally drunk) is common and pilots probably often perform the most difficult parts of the flight while under its effects. I would think the risks of pilots sleeping (and, very rarely, getting caught unprepared for an emergency) would be minimal compared to the risks of pilots being regularly incapacitated by fatigue during the most difficult parts of the flight.