What Is Driver Fatigue?
Truck Driver fatigue is a state of physical and mental exhaustion that reduces a Driver’s ability to operate a vehicle safely. Fatigue can develop gradually over the course of a long shift or appear suddenly due to poor sleep, illness, stress or extended periods of monotonous driving. Unlike simple tiredness, fatigue can seriously impair concentration, awareness and reaction times, increasing the likelihood of a collision.
Fatigue affects every Driver differently, but it is particularly dangerous for professional Truck Drivers who spend long hours on the road and often work irregular schedules. A fatigued Driver may struggle to focus, miss important hazards, drift between lanes or experience slower reactions to changing road conditions. In severe cases, fatigue can lead to microsleeps where a Driver briefly falls asleep without realising it.
Physical and Mental Fatigue
Driver fatigue can be divided into two main categories: physical fatigue and mental fatigue. Physical fatigue occurs when the body becomes exhausted after long periods of activity, inadequate rest or poor-quality sleep. Symptoms can include heavy eyelids, muscle aches, yawning and difficulty maintaining alertness behind the wheel.
Mental fatigue develops when the brain is overworked or overstimulated for extended periods. Long hours concentrating on traffic, navigation and delivery schedules can place significant strain on a Driver’s mental focus. This type of fatigue often leads to poor concentration, slower decision making and reduced awareness of hazards on the road.
Truck Drivers commonly experience a combination of both physical and mental fatigue. Driving for long periods without adequate breaks, particularly on repetitive motorway routes, can quickly reduce alertness and increase the risk of dangerous driving errors.
Why Fatigue is Dangerous for Drivers
Fatigue has a major impact on driving performance and is recognised as one of the leading contributors to serious road traffic accidents. A tired Driver is less able to react quickly to hazards, judge speed and distance accurately or maintain consistent control of their vehicle.
Research has shown that being awake for extended periods can impair driving ability to a similar degree as alcohol consumption. Fatigued Drivers are more likely to drift between lanes, miss road signs and fail to respond appropriately to sudden changes in traffic conditions.
One of the most dangerous aspects of fatigue is that Drivers are not always aware of how impaired they have become. As tiredness increases, concentration and judgement decline, making it more difficult for Drivers to recognise when they are no longer fit to continue driving safely.
Truck Driver Fatigue Statistics
Statistics show that at least 300 people are killed each year as a result of Drivers falling asleep at the wheel and around four in ten tiredness-related crashes involve someone driving a commercial vehicle.
These Truck Driver fatigue statistics make for uncomfortable reading, but the reality is that they might only be scratching the surface of the issue, it is not always clear if a crash was caused by tiredness and so the actual figures could be higher.
Sleep Related Vehicle Accidents (SRVAs) have been found to have a greater likelihood of resulting in someone being killed or seriously injured than most accidents due to the sleeping Driver’s inability to apply the brakes before impact.
Professional Drivers are particularly at risk from tiredness because they typically spend much longer hours at the wheel. Drivers trying to fight off sleep often experience ‘microsleeps’, where they are nodding off for anywhere between two and 30 seconds at a time, often without realising or remembering it. This is more than enough to cause a fatal crash.
Causes of Driver Fatigue
During a study into the causes of Driver fatigue, Brown (1994) identified five causes of Truck Driver fatigue:
- Lack of sleep
- Poor sleep
- Time-on-task (the time spent driving)
- Monotonous tasks
- Individual characteristics and genetics including medical conditions
For Truck Drivers, the time-on-task should be seen as the total working time as professional Drivers often perform many more tasks than the job of driving alone. Long working hours often go together with an early start, night driving and reduced sleep all of which have a dramatic impact on Truck Driver fatigue levels.
Driving at Night
Night driving is recognised as a major risk factor for traffic accidents. In one large study involving 80 Drivers who had completed more than 200,000 miles of driving following one of four driving schedules, researchers reported that Driver alertness was more consistently related to time of day than to cumulative time-on-task (i.e. time spent driving).
Despite evidence to support the argument that time of day has a greater effect on Truck Driver fatigue levels than previously recognised, current driving legislation does not take into consideration the interaction between continuous driving duration and the time of day. It is therefore important for Truck Drivers to understand the correlation and pay attention to how they feel, how tired they are and if their concentration levels are dropping so they can take more regular breaks if needed.
Long Hours and Shift Work
Long working hours and irregular shift patterns are among the most significant contributors to Truck Driver fatigue. Many professional Drivers begin work early in the morning, drive late into the night or work rotating shifts which disrupt the body’s natural sleep cycle.
The body operates according to a circadian rhythm which controls periods of wakefulness and sleepiness. Driving during the night or in the early hours of the morning can therefore be particularly dangerous because alertness naturally decreases during these periods.
Extended shifts can also limit the amount of quality sleep Drivers are able to get between working days. Even when Drivers have enough time off, sleeping during daylight hours or in unfamiliar environments may reduce sleep quality and leave them feeling exhausted before their next shift begins.
Stress and Mental Strain
Stress and mental strain can significantly contribute to Driver fatigue and reduce concentration behind the wheel. Truck Drivers often face demanding delivery schedules, heavy traffic, poor weather conditions and long periods away from home, all of which can affect mental wellbeing.
High stress levels can make it difficult to relax and sleep properly during rest periods. Over time, ongoing stress may lead to exhaustion, irritability and difficulty concentrating while driving. Mental fatigue caused by stress can be just as dangerous as physical tiredness.
Professional Drivers should pay attention to their mental health and take practical steps to manage stress wherever possible. Taking regular breaks, maintaining communication with employers and allowing enough time for rest can all help to reduce the effects of mental strain.
Poor Diet and Dehydration
Poor nutrition and dehydration can also have a significant effect on Driver alertness and energy levels. Truck Drivers often work long shifts with limited access to healthy food options, making it easy to rely on fast food, sugary snacks and caffeinated drinks.
Although sugary foods and caffeine may provide a temporary boost in energy, they are often followed by a sudden drop in alertness which can worsen fatigue. Skipping meals or eating large heavy meals before driving may also contribute to drowsiness and reduced concentration.
Dehydration can impair mental performance, slow reaction times and increase feelings of tiredness. Drinking plenty of water and maintaining a balanced diet can help Drivers remain alert and focused throughout their journeys.
What Impact Does Truck Driver Fatigue Have?
Driving for relatively long periods in a monotonous driving environment has a clear negative effect on a Driver’s abilities and reactions. All of the following occur during Truck Driver fatigue:
- Reduced reaction time
- Vulnerability to distraction
- Reduced vigilance
- Impaired judgement
- Impaired higher mental functioning
- Inability to deal with the unexpected
- Poor decision making
- Greater risk taking
- Reduced peripheral visual field
Taking frequent breaks will counteract the effects that long periods of monotonous driving could have. In 2014, a real road driving study was conducted with thirty-three commercial Drivers. The impact of continuous driving time on driving performance and the effect of rest time on the recovery of the driving performance was studied.
The analysis revealed that driving time had a significant effect on fatigue and driving performance. After two hours of driving, both fatigue and driving performance began to deteriorate and after four hours of driving, all of the driving performance indicators changed significantly except for depth perception.
Adequate rest time eliminated the negative effects of fatigue to varying degrees. A 15-minute rest allowed Drivers to recover from a two-hour driving task, but the rest period needed to be prolonged to 30 minutes for three to four hours of continuous driving.
Highway Hypnosis
A phenomenon which is sometimes confused with Driver fatigue, but which is in fact quite different is ‘driving without awareness’ (DWA), also known as Highway Hypnosis. DWA is where the Driver begins driving on autopilot, paying no active attention to the driving task. At a certain moment, the Driver ‘awakes’ and cannot remember actually driving the previous few minutes.
DWA occurs due to the monotony and repetitiveness of the driving task, not necessarily because Drivers are tired from time on task, lack of sleep, poor quality sleep or the time of day. Unlike micro-sleep during which the eyes are closed for at least two seconds, during DWA the eyes stay open.
Researchers, Karrer et al. (2006) asked a representative sample of 83 German Drivers to perform a monotonous driving task on a motorway for two hours to identify the symptoms of driving without awareness. The study found that driving without awareness was displayed in five ways:
- Staring into space
- Staring at the road
- Head moves upwards or downwards
- Eyes start a rolling movement
- Squinting
It is important to stay alert and keep your brain active while you are driving to minimise the likelihood of experiencing DWA. Making sure you are paying attention to the road and other road users will help to combat the risk of driving without awareness on monotonous journeys. Listening to audiobooks, podcasts and music will all help to keep your mind active and focused on the task in hand but taking frequent rest breaks will always be the safest and most effective option.
Common Truck Driver Fatigue Prevention Myths
If you drive when tired, it is impossible to stop yourself eventually nodding off at the wheel. Despite popular belief, winding down the window or turning up the radio does not prevent sleep.
A 2012 study investigated the effects of two of the most commonly used countermeasures against Driver sleepiness - opening the window and listening to music.
In total, 24 individuals participated in the study. Eight participants drove without countermeasures as a control group, while 16 participants received intermittent 10-min intervals of an open window (2 cm opened); and listening to music, during both day and night driving on an open motorway.
Extended blink duration was used as the measure for sleepiness throughout the study.
Researchers found that listening to music had only a minor effect on sleepiness compared with the bigger effects that night driving and driving duration had. An open window had no effect on sleepiness at all. Therefore, despite their popularity, opening the window and listening to music cannot be recommended as effective countermeasures against Truck Driver fatigue.
Effective Ways to Prevent Driver Fatigue
Fatigue management for Truck Drivers always comes down to sleep and rest. It is imperative that Drivers have a good night’s sleep before any journey. Doctors recommend we get eight hours’ sleep a night to keep our bodies and minds refreshed and alert. This is critical for safe driving.
If you feel tired, you should stop in a safe place as soon as possible; the government recommends Drivers take a break at least every two hours.
Professional Truck Drivers have their working hours controlled by law and are required to take breaks totalling at least 45 minutes in eight-and-a-half hours driving, followed by a break of at least 30 minutes: an average of nearly 10 minutes’ rest for every hour driving.
If you wake up in the morning feeling exhausted, struggle to stay awake, snore or wake up struggling to breathe, you may suffer from a relatively common condition called sleep apnoea. Sufferers are at a significantly increased risk of crashing due to fatigue. The condition is fully treatable, so if you experience symptoms, stop driving immediately and see a doctor.
Never feel under pressure to ignore feelings of fatigue and push on through to make a delivery on time. Your safety is paramount and comes before anything else so if you feel tired, distracted or that you are losing concentration, find somewhere safe to stop and take well deserved a break.
When to Stop Driving
Recognising when to stop driving is one of the most important aspects of fatigue management for Truck Drivers. Continuing to drive while tired places the Driver, other road users and pedestrians at serious risk. Many fatigue-related accidents occur because Drivers attempt to push through feelings of exhaustion in order to complete a journey or meet a delivery deadline.
Drivers should never ignore the early signs of fatigue. Taking a short break before tiredness becomes severe can help to prevent dangerous lapses in concentration and reduce the likelihood of falling asleep at the wheel. If fatigue continues after a rest break, the safest option is to stop driving completely and get adequate sleep before continuing the journey.
Warning Signs of Severe Fatigue
There are several warning signs that indicate a Driver may be too tired to continue driving safely. Common symptoms include frequent yawning, difficulty focusing, heavy eyelids, drifting between lanes and missing road signs or exits.
Drivers experiencing fatigue may also struggle to remember the last few miles travelled or notice that their reactions are becoming slower. Microsleeps are another serious warning sign and can occur without the Driver realising it.
If any of these symptoms occur, the Driver should stop as soon as it is safe to do so. Ignoring warning signs of fatigue can quickly lead to a serious or fatal collision.
What to Do When You Feel Unsafe to Continue
If you feel too tired to continue driving safely, you should pull over in a safe and legal location as soon as possible. Service stations and designated rest areas provide the safest environments for Drivers to stop and recover.
Taking a short nap and consuming caffeine may provide temporary relief from fatigue, but these measures should never be relied upon as a long-term solution. The only effective treatment for fatigue is adequate rest and sleep.
Drivers should also communicate with employers or transport managers if fatigue is affecting their ability to complete a journey safely. No delivery or schedule is more important than protecting lives on the road.
