Caffeine protects against crash risk for long distance heavy vehicle drivers

Long distance commercial drivers who consume caffeinated substances such as coffee to stay awake while driving are significantly less likely to crash than those who do not, even though they drive longer distances and sleep less, finds a study published today on

Previous studies have recognised that the use of caffeine is an effective strategy for improving alertness, but have been inconclusive regarding the effectiveness of caffeine in reducing the likelihood of injury.

Researchers from Australia including from The George Institute for Global Health, carried out a study of long distance commercial vehicle drivers, investigating, among other factors, the effects of caffeine on the likelihood of a crash.

Forty three percent of drivers reported consuming substances containing caffeine, such as tea, coffee, caffeine tablets, or energy drinks for the express purpose of staying awake.

The results show that drivers who consumed caffeine to help them stay awake were 63% less likely to crash than drivers who did not take caffeinated substance.

Lead author of the paper, Lisa Sharwood of The George Institute and the University of Sydney says that the results should be interpreted cautiously.

"Caffeine may seem effective in enhancing alertness, but it should be considered carefully in the context of a safe and healthy fatigue management strategy; energy drinks and coffee certainly don't replace the need for sleep," Ms Sharwood said.

"The study shows that the consumption of caffeinated substances can significantly protect against crash risk for the long distance commercial driver," she said. "The benefit, however, is likely to be short-lived. Having regular breaks, napping and appropriate work schedules are strongly recommended in line with national fatigue management legislation for heavy vehicle drivers".

Long distance drivers routinely experience monotonous and extended driving periods in a sedentary position, which has been associated with wake time drowsiness, increasing the likelihood of crashing. Caffeine is one of the most commonly used stimulants worldwide that has been shown to increase alertness in shift workers. However, it can also affect the quantity and quality of sleep.

Having a previous crash in the past five years increased the risk of crash by 81% and this remained significant.

The study was conducted between 2008 and 2011 in New South Wales and Western Australia. Participants were long distance drivers whose vehicle mass was at least 12 tonnes. The study compared 530 drivers who crashed their vehicle while on a long distance trip (cases) with 517 drivers who had not had a crash in the previous 12 months (controls).

The study was a collaboration between the University of Sydney, Monash University, University of New South Wales, Curtin University, Queensland University of Technology and Police Departments in New South Wales, Western Australia and Queensland, and was funded by the Australian Research Council, the Australian Government Department of Infrastructure, Transport, Regional Development and Local Government, DiagnoseIT, the National Transport Commission, Queensland Transport, Roads and Traffic Authority of New South Wales and Main Roads Western Australia.