New research has revealed that it doesn't take a three-hour drive on the freeway to succumb to fatigue: it can happen much, much sooner.
According to the Queensland University of Technology, drivers can show extreme levels of fatigue after just 40 minutes of driving, if the motorist has been dragged from bed too early.
The university's Centre for Accident Research and Road Safety - Queensland (CARRS-Q) found that even rising even an hour earlier than normal can cause dangerous levels of sleepiness.
The study saw participants forced from their beds at 5am, and then undertaking a driving test either in the morning or the afternoon. Participants were asked to stop driving when they felt too tired to drive safely.
"Most of the participants decided to stop driving and take a break after about 40 minutes and most of them were able to take a nap afterwards," lead investigator Chris Watling said.
"The finding suggests that drivers can experience very significant levels of sleepiness within the commonly promoted 'stop and revive' recommendation of driving two hours before a break."
Using the Karolinksa sleepiness scale, a rating of between one and nine, participants rated their sleepiness at level eight, right at the high end of the scale.
"The risk of crashing is 15 times more likely when you get to that level of sleepiness," Mr Watling said.
Worryingly, some drivers who had microsleeps at the wheel, or were nodding off, would push on for another twelve minutes.
"This suggests they knew they were extremely tired but pushed on to be awake for a further twelve minutes."
Mr Watling will present his findings at the Australasian Sleep Conference in Darwin running from today until Saturday.
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