ABSTRACT
Fatigue-related accidents are a particular problem for professional drivers. Although subject to regulations about how long they can drive, long-distance lorry drivers work long shifts, often interspersed with little or poor sleep, and they drive for prolonged periods on monotonous high-speed roads, often at night. Visual sampling of the environment becomes dominated by expectations, and the field of view tends to become increasingly narrow. Counter-intuitively, fatigued individuals often show preserved performance on complex tasks but not simple ones, so driving is most likely to be affected when it appears to be most straightforward. Drugs may impair driving performance directly, by affecting cognitive and motor performance, or indirectly by influencing mood. Three most commonly used drugs that are likely to affect driving: alcohol, cannabis and tranquilisers. Tranquilisers are likely to impair driving ability; the psychological effects of barbiturates are generally similar to those produced by alcohol, ranging from euphoria to sleep, depending on the concentration.
