The researchers have proved, once and for all, that
coffee really can keep drivers alert for up to three
hours.
Image: iStockphoto 

The eyes have it, say researchers at Swinburne University of Technology after using a new type of optical instrument to measure the effects of caffeine on reducing drowsiness.

Natalie Michael and Dr John Patterson of Swinburne’s Sensory Neuroscience Laboratory set out to resolve the question: Does drinking coffee provide a reliable lift in alertness that can be measured scientifically and consistently?

The Swinburne team collaborated with Dr Murray Johns at Sleep Diagnostics Pty Ltd, and Dr Caroline Owen who is now based at the Peter MacCallum Cancer Centre Research Division.

Over the years there have been a range of recommendations for staying alert on long drives. These have included stopping for a brisk walk, taking a power nap, and drinking coffee.

“However, road safety authorities were faced with conflicting evidence on the benefits of drinking coffee,” Dr Patterson said.

“Some research showed heightened alertness after caffeine administration, whereas other studies did not.

“In our project we used the Australian-designed OptalertTM, which measures drowsiness by observing total duration of eye blinks and the ratio of amplitude and velocity of eye closure during blinking. Even in our well-rested subjects, the Optalert detected repeatable increases in alertness,” he said.

The subjects in the Swinburne project were aged between 18 and 29, a primary target age group for road safety authorities because of their over-representation in drowsy driving incidents.

Test subjects were given either a placebo or a capsule containing 200 mg of caffeine, which is roughly equivalent to two cups of coffee.

Those given the caffeine also showed improved reaction times, which like the improved alertness measured by the Optalert, persisted for about three hours.

The Optalert resembles a set of spectacle frames without lenses. Low intensity infra-red light is directed at the eyes. The infra-red is reflected back and detected by sensors in the frames. The pattern of light reaching the sensors changes as the eyes move and the subject blinks.

The Optalert is available commercially for use as a drowsiness warning system for long-distance professional drivers.

The study was published in the journal Psychopharmacology in October 2008.