Driver advice: fatigue

Drivers can pledge to
– take regular breaks and never drive tired.

Everyone can pledge to – look out for friends and loved ones by ensuring they only drive if they're fit for it.

 Fatigue is a major cause of road crashes. Tired drivers had slower reaction times and suffer from reduced attention, awareness, and ability to control their vehicles. Research suggests driving tired can be as dangerous as drink-driving.

Statistics show that fatigue is a factor in 9% of fatal and 4% of serious injury crashes. Alcohol/drugs and speed were also contributing factors in 56% of the fatal crashes involving fatigue, and 87% of fatal fatigue crashes occurred on the open road [1]. However, it is likely that the true figures of crashes involving fatigue are higher because fatigue is hard to spot and, unlike alcohol, police can't test for tiredness. Worldwide, it is estimated that between 10% and 20% of all road crashes are fatigue-related.

Factors that contribute to driver fatigue 


Many factors can contribute to driver tiredness and increase the risk of being involved in a fatigue-related crash. These include:

Lack of sleep or disturbed sleep: This could be due to disruptions in life such as a new baby, busy schedules, stress or even warm/humid weather, or could be due to sleep disorders such as narcolepsy, insomnia or sleep apnoea.

Time of day: The most common times for drivers with normal sleep patterns to fall asleep at the wheel are early morning (2am - 6am) and early afternoon (2pm - 4pm). These times are when the body clock (circadian rhythm) reaches a natural dip, causing drowsiness and reduced concentration. 

Stress: Tiredness and difficulty concentrating are typical symptoms of stress.

Irregular sleep patterns: This can be a problem caused by irregular work shifts and switching from day to night shifts without having sufficient time off in between for your body clock to adjust. Research has found that shift workers are particularly high risk for sleep-related crashes.

Driving for long periods: Research has found driving deteriorates after two hours of continuous driving, as you become less able to concentrate, and slower to react to hazards. The longer you drive, the more rest you need to recover driving performance. Breaks are therefore recommended every two hours.

Vehicle engineering: Modern vehicles are usually quiet and comfortable for the driver, meaning a more relaxed drive. This can lull drivers, particularly in vehicles fitted with comfort-enhancing features such as cruise control.

Medication: Some prescription and over-the-counter drugs can cause drowsiness. Medications may carry warnings that are not clear they impair driving, for example small print that only advises not to operate heavy machinery.

Signs of fatigue

Fatigue doesn't occur without warning, and most people recognise the symptoms but many still underestimate the dangers of continuing to drive while tired.

Warning signs include:

  • increased difficulty concentrating
  • yawning
  • heavy eyelids
  • eyes starting to 'roll'

By the time your head starts nodding, you could be having a 'microsleep'.

A microsleep occurs when someone nods off for between two and 30 seconds without realising or remembering it, often known as head-nodding. This occurs when people are tired but trying to stay awake, most common in monotonous situations.

After a microsleep a driver may feel like they've just briefly nodded their head, but they have actually been asleep. During this time, they will have been completely unaware of the road and unable to control their vehicle. Simulator studies have shown a clear relationship between microsleeps and crashes.

How to manage the risks of fatigue

Plan ahead

Plan ahead so you're well-rested before driving and never embark on a journey when you're already feeling tired. If you know you have to drive the next day, especially a longer journey, make sure you get a good night’s sleep.

When planning a long journey, allow time for regular breaks - at least 15 minutes at least every two hours - although you need to stop as soon as possible if you start to feel tired (see below). Book an overnight stay if needed, either to break up a long journey and/or to ensure you're well-rested before returning home.

Avoid driving at times of the day when you're most susceptible to tiredness, like at night, in the evening after a long day, or in the mid-afternoon, when most people experience a 'dip'.

If you drive for work

Ensure there is time in your schedule for regular break periods to rest - 15 minutes every two hours is safest - and look at whether there are alternatives to driving, such as video conferencing or taking public transport to appointments.

If you drive a truck or bus, be aware of legislation covering the hours you are allowed to drive, and make sure you take the required rest breaks. Even if you fall behind schedule or get caught in traffic, always take your breaks. Safety comes before deadlines. Your employer should have a policy on driver tiredness that complies with health and safety laws and makes clear that safety is the priority. When you're driving on company time, you and your employer have responsibility for making sure you're not endangering yourself and others.

Brake advises companies on preventing fatigue and other issues to do with at-work road safety. Find out more at

tired2 250If you feel tired

Listen to the warning signs and pull over somewhere safe as soon as you can. Winding down the window or turning up your music does not help you to stay awake. 

Having a caffeinated drink (an energy drink is better than coffee as it's a more reliable source of a reasonable dose of caffeine) followed by a 15 minute nap can help to temporarily stave off tiredness, but bear in mind this is only a temporary aid.

If you are still feeling tired after your nap, or you still have a long way to go, you need to stop and get a proper night's sleep, which is the only solution to tiredness. Whatever you do, only continue your journey when you're feeling fully refreshed.

Medical conditions

Some medical conditions and medication can affect your sleep and/or make you drowsy at other times. Tell your doctor about any health problems that affect your sleep, and check whether any medications affect tiredness. If you drive for work, you should also tell your boss about any medical conditions or medication that could affect your sleep and driving.

Sleep apnoea

Sleep apnoea is a relatively common, but often undiagnosed condition that puts sufferers at great risk of tiredness crashes. Sufferers briefly stop breathing repeatedly while they are asleep. While the sleeper may not realise it, this interrupts their sleep and results in daytime sleepiness, which can result in falling asleep at the wheel. Signs of sleep apnoea include loud snoring, disturbed sleep, regularly waking up coughing, fighting for breath during sleep, and falling asleep in the daytime. The highest-risk group for sleep apnoea are overweight middle-aged men, although it can affect other groups too.

If you think there is a chance you have sleep apnoea, seek medical advice. Sleep apnoea is treatable, and if left untreated can increase the risk of high blood pressure, stroke and heart attacks, as well as driver fatigue crashes. The sooner you see a doctor, the better.


[1] Fatigue crash statistics 2020 - 2022, Ministry of Transport. 

Last updated January 2024

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