Re Lawyerboy's post, and putting aside the fact that some choose to do jobs with erratic hours.
Have you ever tried sleeping through the day, trying to get enough rest before a minimum 8-hour duty starts at 5pm? When it's daylight outside, when doorbells or phones ring continously, when children are playing outside, when neighbours are cutting their grass, when the other half needs to be doing the housework? Earplugs don't work that effectively. You can't have a drink or take anything from a chemist to help you sleep because of the 8-hour ban on drinking before duty starts.
It's damn difficult but one's life outside the airline (or any other job involving constantly changing shift patterns) goes on, that's why some people will be awake from 6am in the morning even when standby doesn't start until 5pm. But usually not through choice.
None of this really justifies the actions of anyone who causes an accident when they've been awake and working for 24 hours or more, but it has to be taken into account.
Katie C.