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Driver Fatigue

Driver fatigue

Last year driver fatigue caused one in five fatal crashes on our roads. From a momentary loss of concentration to feeling tired or sleepy, driver fatigue can lead to losing control of your vehicle. The risk of a fatal fatigue crash is four times greater between 10pm and 6am than for the rest of the day.


Fatigue is a general term commonly used to describe the experience of being "sleepy", "tired" or "exhausted". Fatigue is both a physiological and a psychological experience.

Driver fatigue can severely impair judgment and can affect anyone. It is particularly dangerous because one of the symptoms is decreased ability to judge our own level of tiredness. Other symptoms vary between drivers, but may include:

yawning. poor concentration. tired or sore eyes. restlessness. drowsiness. slow reactions. boredom. feeling irritable. making fewer and larger steering corrections. missing road signs. having difficulty in staying in the lane. microsleeps. 

It is important to note that driver fatigue is not simply a function of time spent driving but relates to many factors including hours since last slept (hours of wakefulness) and time of day or night.


High risk times for fatigue-related fatal crashes are:

Night-time/early morning




Fatigue-related crashes at these times of the day coincide with dips in the body's circadian rhythms, which program us to feel sleepy at night when we would normally be asleep and to a lesser extent in the afternoon hours.

Fatal crashes identifying fatigue as a factor are more likely to occur during public and school holiday periods.  Nearly 30 per cent of all fatal fatigue accidents occur during public or school holidays.


Most fatigue-related crashes occur on country roads. In 1998-2002, 79 per cent of fatigue-related fatal crashes occurred on country roads.

Fatigue-related crashes also occur in urban areas. In 1998-2002, 21 per cent of fatigue-related crashes occurred on urban roads in Ireland.

Of all fatal crashes where fatigue was identified as a factor, 37 per cent involved head on collisions.


Driver Reviver / Rest Areas

To help reduce driver fatigue,



 Rest areas are places where you can park safely, get out of your car and refresh yourself before continuing your journey.  Rest areas are available 24 hours a day, all year round and are clearly signposted. Service centres, petrol stations, parks and country towns are other places you can stop and take a break from driving.Microsleep

A microsleep is a brief and unintended loss of consciousness characterised by head snapping, nodding or closing your eyes for more than a couple of seconds. Microsleeps occur when you try to stay awake to perform a monotonous task such as driving.

Microsleeps can last from a few seconds to several minutes and often people are not aware that a microsleep has occurred.

During a 4 second microsleep a car travelling at 100km/h will go 111 metres while completely out of the driver’s control.


The sleep & wake cycle

The best way to prevent driver fatigue is to make sure you have enough sleep before driving regardless of the length of your trip. There are 3 sleep factors to consider before deciding whether or not to start driving.

1. Circadian rhythms

Circadian rhythms are physiological cycles that follow a daily pattern. We are "programmed" by our circadian rhythms to sleep at night and to be awake during the day.

During night time hours and to a lesser extent during afternoon "siesta" hours, most types of human performance are significantly impaired, including our ability to drive.

Problems occur if we disrupt our natural sleep cycles (eg by staying awake during the night), do not get enough sleep, or get poor quality sleep.Circadian rhythms cannot be reversed. Even if you have been working nightshifts for many years, your body will still be programmed to sleep at night.

2. Sleep debt

The human body requires a certain amount of sleep each night to function effectively. The average amount of sleep a person needs is 8 hours. When we   reduce the number of hours we sleep at night we start to accumulate what is

called a 'sleep debt'.

Sleep debt is defined as the difference between the hours of sleep a person needs and the hours of sleep a person actually gets.

For example, if a person needs 8 hours of sleep per night but only gets 6 hours of sleep one night, they have a sleep debt of two hours. These lost hours of sleep need to be replaced.

When we have sleep debt, our tendency to fall asleep the next day increases. The larger the sleep debt, the stronger the tendency to fall asleep.

Sleep debt does not go away by itself. Sleeping is the only way to reduce your sleep debt.

3. Sleep inertia

Sleep inertia is the feeling of grogginess after awakening and temporarily reduces your ability to perform even simple tasks.

Sleep inertia can last from 1 minute to 4 hours, but typically lasts 15-30 minutes.

The severity of sleep inertia is dependent on how long you have been asleep and the stage of sleep at awakening.

Effects can be severe if a person is very sleep deprived or has been woken from a deep sleep stage. However, sleep inertia can usually be reversed within 15 minutes by activity and noise.

Sleep inertia can cause impairment of motor and cognitive functions and can affect a person's ability to drive safely.

Sleep inertia can be very dangerous for people who drive in the early morning hours and shortly after waking up from a sleep.



Don’t ignore the early

Facts about driver fatigue

Get a good night’s sleep before

Don’t ignore the early