I don't know if this necessarily applies to flying a plane or a helicopter, but there are certain activities that are described as long periods of boredom interspersed with moments of abject terror.
Mr. Belenky, we talk about flight time, but I'm wondering what actually goes on while the pilot is awake, especially on the long-haul flights. Everything seems to be automated. Are they just sitting there twiddling their thumbs? I've never spent any time on a flight deck, but could there be long periods of mental inactivity, if you like, that really take the edge off just as much as sleep?