Road accidents caused by sleepy drivers: Update of a Norwegian survey

► We collect self-reports on sleepiness from accident-involved drivers in Norway. ► We find that sleepiness is responsible for 1.9 and 3.9 per cent of all types of road accident. ► We find that sleepiness behind the wheel has decreased from 1997 to 2008. ► We isolate factors associated with sleepiness-related accidents. ► We isolate factors associated with incidents of sleepiness behind the wheel.