Sleepiness, countermeasures and the risk of motor vehicle accidents

Abstract

There are several factors that increase the risk of driver sleepiness and result in increased accident risk. Modern vehicle design enables the driver to travel at high speeds and for long distances in a comfortable and often sleep promoting driving environment. Recent decades have seen an increase in shift work and apparent trends for reduced sleep length, which combine to increase driving risk, particularly with night driving. The young appear more vulnerable to the effects of reduced sleep, night driving and driving for long periods. Sleep related vehicle accidents represent a high proportion of vehicle accidents with the young and truck drivers standing out as vulnerable groups. People appear to be relatively poor predictors of imminent sleep onset so that driver warning systems would provide a valuable countermeasure, but unfortunately reliable commercial systems are still some years away. Future warning systems will need to account for the marked individual differences seen in levels of driver sleepiness, impaired performance and associated risk levels. Driver education programmes are required warning of the increased risks of driver sleepiness associated with extended waking, too little sleep, and driving during the circadian low period. Drivers should also be made aware of strategies helping to maximise sleep and optimise arousal which are of particular use for night driving and shift work. These could include the use of appropriate hypnotics to maximise available sleep, or melatonin and light exposure to enhance phase shifting or improve sleep and waking scheduling. Practical countermeasures used by drivers that have been assessed and appear beneficial include the use of brief naps and caffeine. © 2009 Birkhéuser Verlag/Switzerland.