In answer to the question "in the past 12 months, have you ever driven while sleepy?" 63% of participants responded never, 36% a few times in the year, 0.8% about once a month, 0.3% about once a week, and 0.2% more than once a week.
There was a strong association between self assessed driving while sleepy and the risk of serious road traffic accidents over the next three years. This risk increased with reported frequency of driving while sleepy.
For example, participants who reported driving while sleepy "a few times in the year" were 1.5 times more likely to have been involved in a serious RTA compared with those who reported not driving while sleepy over the same period. And those who reported doing so "once a month or more often" were nearly three times more likely to have been involved in a serious RTA.
Further analysis did not change this association and follow-up questionnaires in 2004 also found a similar trend.
These results clearly show that self assessed driving while sleepy is a powerful predictor of serious road traffic accidents, and suggest that drivers are aware that they are sleepy when driving but do not act accordingly, say the authors.
Drivers may either underestimate the impact of sleepiness on their driving performance or overestimate their capacity to fight sleepiness.
Messages on prevention should therefore focus on convincing sleepy drivers to stop driving and sleep before resuming their journey, they conclude.
Another study published today in the same journal, indicates that injury rates on England's roads remain high, despite government claims that they have fallen substantially. The number of serious injuries on England's roads is much higher than Government figures suggest, say the authors of this study.
Government targets for England look to reduce by 40% overall the number of serious injuries and deaths on the nation's roads by 2010, (compared with a starting point - baseline - of the 1994-8 average figures). The target for those aged 15 or under is higher, at 50% reduction.
But when researchers compared police statistics (which the Government uses for its figures), and hospital statistics between 1996 and 2004, they found large discrepancies.
Police figures showed that by 2004, numbers of those killed or seriously injured had dropped by almost a third (from 86 per 100,000 population, to 59 per 100,000). However, the police statistics showed a much smaller decline in the number of people killed than the number seriously injured.
Police statistics showed a 32% drop in serious but non-fatal injuries. However, the researchers found that hospital figures for non-fatal road injuries showed that rates had hardly changed between 1996 and 2004.
The authors suggest the discrepancies are probably down to an increase in under-reporting of injuries in the police statistics and that, if there has been a decline in injuries, it is probably only in those considered by the police to have been minor.
More investigation is needed, say the authors, since the findings cast doubt on whether there has been much progress on the Government's target to date - and on its likelihood of being met by 2010.
In practical and policy terms, much more needs to be done to ensure that there are real and substantial reductions in serious injuries not only on England's roads but as well in many other countries of the world.
Address: 5636 Lemon Ave.
Dallas TX 75209
Phone: +1 214 5203694