Does caffeine really reduce driver fatigue?

Defence researchers have discovered that caffeine only marginally reduces drowsiness in drivers but can, however, significantly reduce driving errors.

The results came from a fatigue study that was part of extensive research looking into ways of reducing fatigue in individuals and teams in the armed forces — in particular, Army vehicles.

The study examined the effects of caffeinated chewing gum on both drowsiness and driving performance on people who were sleep deprived.

Participants in the study were kept awake for 50 hours and, during this period, were required to drive on 15 occasions in a simulated vehicle for 40 minutes at a time. One half of the group was given caffeinated gum while the other half was given a placebo of the same gum with no caffeine.

Defence Science and Technology Group Senior Cognitive Scientist Eugene Aidman said caffeinated gum was used to administer the caffeine as it takes only 10 minutes for most of the dose to be absorbed by the brain and lasts for 90 minutes, whereas drinking coffee takes 30–90 minutes to be absorbed for an unpredictable amount of time.

The simulated driving study measured levels of drowsiness with a spectacle frame-mounted infrared sensor registering blink velocity. Lane-keeping and speed-variability measures were also used to assess driving performance.

The researchers found a relationship between growing drowsiness and driving errors in the placebo group. In the caffeine group there was a much lower incidence of driving errors, despite the growing drowsiness over the period of sleep deprivation.

Researchers said that while the findings are relevant to Defence, they have significant implications for civilian applications such as emergency services and long-haul transport.

Image courtesy of Defence

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