Driver fatigue is estimated to be a (contributing) factor in 15 to 20% of crashes, but estimates in individual studies vary widely. Drivers who are tired are less attentive and react less quickly and less adequately than drivers who are not tired. They also get irritated and frustrated more easily.

In the Netherlands, licence acquisition courses for category B (passenger cars) are concluded by a theoretical and a practical test. Driving lessons are not obligatory, but without them passing the practical test is virtually impossible. For practical reasons, the effectiveness of drivings tests and driver training is hard to assess in a scientific way. A few studies of the effectiveness of theory tests and practical driving tests are indeed available. These do, however, not show a marked relation between crash risk and driving test performance or driver training.