Drowsy drivers recognise they are sleepy long before becoming impaired. Yet many ignore the warning signs, Australian research has revealed.
Presented at the Sleep DownUnder 2019 Conference last October, a three-day conference held by the Australasian Sleep Association, the study set out to investigate whether people can recognise their own subjective sleepiness.
A supporting study also found passengers could accurately rate sleepiness in their driver.
“We’ve been able to show that, contrary to other research, people are aware of sleepiness, in themselves and others,” Monash University’s Associate Professor Clare Anderson, from the CRC for Alertness, Safety and Productivity, said.
“It is critical that individuals act on these feelings. Don’t start driving or continue driving if you feel sleepy, and don’t get into a car with a driver who looks sleepy or says they are sleepy.”
Statistics show drowsy driving contributes to 72,000 crashes, 41,000 injuries and 800 deaths in Australia every year, with about 20% of motor vehicle crashes caused by fatigue and one Australian dying every day after falling asleep at the wheel.
The study involved 18 adults undergoing 40 hours of wakefulness followed by various tests for sleepiness, vigilance, including microsleeps and slow eye movement, and signs that the brain was falling asleep.
“Interestingly, we found that a person’s subjective feelings of sleepiness occur first, followed by performance impairment later, followed later still by physiological signs of falling asleep unintentionally,” Associate Professor Anderson explained.
“This indicates that we have an inbuilt-warning system that alerts us long before we are even actually impaired. The trouble is many people either ignore it or don’t see the risk they’re putting on themselves and other road users.”
Researchers believe the findings could have implications for court cases as they suggest drowsy drivers who crash are subjectively aware enough of their sleepiness to make a decision not to get behind the wheel or stop driving.
A related study also presented at the conference found passengers can also recognise signs of sleep deprivation in drivers, suggesting that both drivers and passengers are in a position to make informed decisions about whether to drive while drowsy or be a passenger in such circumstances.
Researchers have called for improved education that urges drivers who feel sleepy to stop.
“While many expensive tools and systems exist to warn drivers of being too sleepy, drivers should never ignore their own ‘free’ warning system,” Associate Professor Anderson said.
