The alertness, mood, and performance problems associated with irregular shift schedules and night work in particular are well known, and because of this, an obvious solution for operator fatigue would be to avoid night work altogether. Night duty should be kept as simple and straightforward as possible because sleepiness will impair cognitive abilities and motivation. Obviously, people who have to work at night must be prepared to deal with the alertness and performance problems that are characteristic of their less-than-optimal work schedules. No matter how tired and sleepy people get from 03:00-6:00, when they finally get a chance to sleep, they often cannot. Right after changing to the night shift, these folks can barely stay awake because their homeostatic and circadian drives are making them so sleepy, and then, since they cannot sleep when they finally get to bed, they are in even poorer shape the next night because they are even more sleep deprived.