- Ten professional truck drivers participated in this simulated driving experiment. The purpose of the experiment was to identify symptoms of fatigue in a prolonged morning drive among drivers that had a full night sleep and were not sleep deprived. Two aspects of the prolonged drive were examined: (a) changes in driving-performance measures, physiological measures and subjective measures over the course of time, and (b) within the drive, variability among three different types of inter-urban road segments with different levels of attentional demands: winding road, two-lane undivided straight road, and a four lane divided highway. Three conclusions can be drawn from this study: (a) task-induced fatigue can occur even for drivers who are not tired or sleep deprived at the beginning of the drive, hence the driving task itself induces fatigue. (b) Individual differences have a major influence on specific fatigue related symptoms and on when (if at all) drivers fall asleep at the wheel. (c) Drivers are active in the way they handle their performance decrement and they can adjust their fatigue-coping strategy to the demands and conditions of the drive.