Fatigue & road safety

Driver fatigue or “drowsy driving” is the loss of driver attention from feeling sleepy or tired. There is a significant increase in the risk of you being involved in a crash if you are driving when tired or drowsy.

Fatigue can be caused by:

  • Being awake continuously for an extended period of time (more than 16 hours)
  • Lack of enough quality sleep.
  • Driving at times when you are normally asleep (eg 12am–6am) or in the afternoon lull (1pm-4pm), when our biological time clock makes most of us feel sleepy.
  • Having a sleep disorder such as sleep apnoea. Symptoms of sleep apnoea include heavy snoring broken by sudden periods of silence, restless sleep and constantly being tired during the day.

Research has shown that going without sleep for 17 hours in a 24-hour period has a similar impairing effect on driving performance as a Blood Alcohol Concentration (BAC) of .05, which carries double the risk of a sober driver. Going without sleep for 24 hours has the same effect as a BAC of .1, which is double the legal BAC limit.

The warning signs of drowsy driving include:

  • microsleeps;
  • constant yawning;
  • drifting in the lane;
  • sore or heavy eyes (and slow eye movements);
  • trouble keeping your head up;
  • delayed/slower reactions;
  • daydreaming
  • difficulty remembering the last few kilometres;
  • variations in driving speed.

If you don’t get enough quality sleep you go into debt, basically “owing” yourself more sleep. The only way to repay this debt is by sleeping. Until you catch up on sleep, you have a greater risk of having a fatigue-related crash. The only effective and sustainable way to combat driver drowsiness is to prevent it occurring in the first place. 

Before you start driving:

  • Make sure you regularly get enough sleep (most people need 7-9 hours a day; young people often require more);
  • Be aware of your biological clock, namely that you are at an increased crash risk when driving between 12am-6am and 1pm-4pm;
  • Plan your route before you go and map out where you’ll take a break. Use the VicRoads rest stop map if travelling in Victoria; 
  • Get a good night’s sleep before travelling (don’t stay up late packing and planning);
  • Don’t start a long trip after a long day’s work; or if you’re feeling tired;
  • Seek medical advice if you regularly feel sleepy or have noticed problems with your sleep; 
  • Don't drink alcohol before your trip. Even a small amount can significantly contribute to driver fatigue;
  • Be aware of the effects of medications you are taking (some may increase drowsiness). See your doctor or pharmacist for advice on your current medication schedule and how it relates to your driving.

When you are driving:

  • Take a short nap (“powernap”) if tired. Research shows that even a small sleep or powernap of 15-20 minutes can temporarily lessen the effects of fatigue for up to 1-2 hours. Caffeine intake immediately prior to a 15-20 minute nap may provide additional benefits, as the alerting benefits of the caffeine will likely kick-in upon waking;
  • Take regular rest breaks every two hours or less as required, to help reduce the effects of fatigue;
  • Stop for at least 15-30 minutes for each break period, leave the car, and stretch and walk around;
  • Where possible, drive for no more than eight hours within a 24-hour period;
  • Where possible, avoid night driving or driving when you would normally be asleep; 
  • Both drivers and passengers should be alert to the signs of sleepiness and how to take action. The only cure for sleepiness is to get enough sleep. If you are feeling sleepy, stop driving as soon as you can; 
  • Plan to share driving on long trips, but only if other drivers are not sleepy or impaired by alcohol or drugs.

    Remember that once you are fatigued the only cure is sleep!

Microsleeps are unintended periods of light sleep that typically last between 2 and 20 seconds. This is commonly referred to as “nodding off”. You lose attention and may stare blankly, have partial or fully closed eyes or find your head snapping upright. 

Microsleeps are more likely to occur when a driver is driving at the times they would normally be asleep and/or when they are tired and trying to stay awake.

Research indicates that drivers are generally aware when they are feeling tired but are unable to predict when they might fall asleep.

The danger for fatigued drivers is that during a microsleep a driver is effectively driving unconscious and does not react to a hazardous situation and will not see a red light or notice that the road has taken a curve or that their vehicle has travelled to the incorrect side of the road.


Shiftworkers are six times more likely to be involved in a fatigue-related crash, particularly when travelling home from work. 

They are at a greater risk when they:

  • drive when their body clock is saying they should be asleep
  • don’t get enough quality sleep because daytime sleep is not as high a quality as night-time sleep.

Fatigue has a direct impact upon workplace safety and productivity. It’s the responsibility of employers and employees to protect themselves, their colleagues and other road users.

Responsibility for fatigue in the workplace:

  • Employers may have a duty of care to protect employees who suffer from fatigue;
  • Employees may have Occupational Health and Safety obligations to advise their employer of their fatigue;
  • Shiftworkers are at a significant risk of  a crash particularly when travelling home from shiftwork.

Sleep apnoea is a serious sleep disorder which occurs when a person's breathing is interrupted during sleep. People with untreated sleep apnoea stop breathing repeatedly during their sleep, which means the brain sends a signal to wake up, so the breathing can return to normal. 

Characteristics of sleep apnoea:

  • being constantly tired during the day;
  • difficulty concentrating during the day;
  • struggling to keep awake during the day;
  • many sufferers are middle-aged males who are often overweight, with symptoms of snoring, restless sleep and pauses in breathing lasting from 10 to 90 seconds while asleep;
  • feeling irritable and experiencing mood changes;
  • loud snoring (though not everyone who snores has sleep apnoea).

There are a range of treatments available. If you think you may suffer from sleep apnoea, consult your local doctor. 


Driving when tired or drowsy means you can’t concentrate properly on your driving and respond as quickly and safely as you should.

Drowsy driving may account for up to 20% of all road crashes.

This section will tell you what causes fatigue and how to prevent or reduce your risk. Including microsleeps, sleep apnoea and the risks of shift work.


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