How fatigue impacts your ability to drive

The reflection of a man yawning in a car's rear vision mirror

Nicola Dowse

Posted November 30, 2022

Driving while fatigued can be as dangerous as driving with BAC of 0.05 or higher. Know how to recognise the symptoms and what to do when they happen.

It’s not uncommon for motorists to get into their vehicle after a long day, with the Transport Accident Commission (TAC) showing 37 per cent of Victorians admitting to driving while tired. 

However, the risks of driving fatigued are real and deadly. Australian Automotive Association (AAA) data shows between 20 to 30 per cent of all Australian car crashes are due to fatigue. 

“Drivers need to make the connection that sleepiness or drowsiness when driving, which many of us are likely to experience, does have significant potential to kill on our roads,” says Silvia Morris, Senior Instructor at RACV Drive School

The effects of fatigue are so severe in fact that driving after 17 to 19 hours without sleep is the same as getting behind the wheel with a blood alcohol concentration of 0.05. If you stay awake a whole day, your ability to drive is the same as having a BAC of 0.1.

“If you are feeling sleepy, don’t drive until you have slept,” Morris says. “If you have not had enough sleep or are feeling exhausted after a long shift at work, you could ask someone else for a lift, take public transport, or use a taxi, or rideshare service.”

A woman driving a car while yawning

Fatigue contributes to an average of 30 road deaths every year with an additional 200 people seriously injured. Photo: Getty. 

What is fatigue and what causes it?

Fatigue is a feeling of tiredness that affects your ability to concentrate, increasing your risk of dangerous driving and accidents. In Victoria, the TAC reports that an average of 30 people are killed every year on the road due to fatigue-related crashes, with an additional 200 people seriously injured. 

Fatigue can strike due to a poor night’s sleep, because you’ve been awake too long, because you’re driving at a time you’re usually asleep, or due to physical or psychological exhaustion (including certain medications). Anyone can experience fatigue, but drivers aged 18 to 25, shift workers, and drivers with sleep disorders are at highest risk.

The physical symptoms include trouble keeping your eyes open, being unable to stop yawning, and daydreaming.  

Fatigue can even cause microsleeps - a condition where you fall asleep for between two and 20 seconds, meaning you're driving unconscious during this time and unable to react to changing road conditions, hazards or other motorists.

Fall asleep for just four seconds while driving at 100kph and you and your vehicle will travel 111 metres uncontrolled.  

Being fatigued also impedes your driving ability, causing drifting, slow reaction times and variations in speed. 

What to do if you notice fatigue while driving

If you start to notice the symptoms of fatigue, pull over as soon as it’s safe to do so.  

The only solution to fatigue is sleep. Even a 20-minute powernap can improve fatigue in the short term, allowing you to safely arrive at your destination or somewhere you can rest properly. Broadly speaking, sleeping in your vehicle is legal within Victoria (just make sure to lock your doors first), but some councils have by-laws preventing it in certain locations. 

“After your nap go for walk for 10 minutes to help you wake up,” says Morris. “If you nap for longer than 20 minutes you might fall into a deep sleep and wake up feeling groggy, so it is a good idea to set yourself an alarm for 20 minutes.” 

Ingesting caffeine before power-napping can help reduce fatigue as well, with the caffeine likely to kick in on waking up. 

Playing loud music, opening the windows, and turning the air conditioning down are not effective at combatting fatigue.  


A roadside sign for a driver reviver site

The only cure for fatigue is rest - even a 20-minute powernap could help ensure you arrive at your destination safely. Photo: Getty.

Driving distance and fatigue

Fatigue is often thought of as a long-distance driving issue. In reality, fatigue can affect drivers whether they’re driving 5km, 50km or 500km, with the TAC indicating that driving itself usually isn’t the cause of fatigue.  

However, it’s still vital to take steps to minimise fatigue when driving long distances. RACV recommends a 15-minute break every two hours while driving – you can even plan your pitstops via the VicRoads interactive rest area map. There are also plenty of interesting places to stop at if you’re travelling eastern Australia’s mighty Hume Highway.

During busy holiday travel periods, Driver Reviver stops also operate across the state. This volunteer-run initiative has been running for more than 30 years, providing 180 sites across Australia where motorists can take a break from driving and enjoy a free hot drink and biscuit.  

“If you have a long drive planned, make sure you have had a good night’s sleep before you start driving,” Morris says. “If it is possible, you should also share the driving with someone else.”

 While not directly related to fatigue, you can help minimise distractions and keep the kids entertained on long trips with car games or blasting the ultimate Australian road trip playlist. Before setting out make sure your car is prepared for a long journey as well. 

High-tech help for fatigue 

Selected car manufacturers have started implementing ‘driver drowsiness detection’ technology in vehicles, including systems that monitor eye and facial movements, vehicle position and steering for signs that the driver may be fatigued.  

Major car brands that use drowsiness detection tech include Ford (introduced in 2011 with the Ford Focus), Kia, Mazda, and Subaru

Mining and trucking industries in Australia have also implemented wearable fatigue detection technologies (such as the SmartCap) that monitors brainwaves for signs of fatigue before physical symptoms appear. 


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