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Fatigue in traffic is a common problem among drivers and also a significant factor in traffic accidents. It occurs with drivers of all ages and is estimated to be a factor in one in five fatal collisions involving a motor vehicle or between two motor vehicles in Finland. Approximately one in seven Finnish drivers have been so tired over the past year that they have feared they will fall asleep while driving.

Fatigue and falling asleep are serious risks

There are different estimates of the prevalence of accidents due to fatigue or falling asleep, but it is almost impossible to determine the exact prevalence. The backgrounds of fatalities are examined more thoroughly in Finland than other accidents leading to personal injury. According to the traffic accident investigation boards, fatigue is a background factor in one in five fatalities with or between motor vehicles. 

Most typical fatigue accidents are head-on collisions or driving off the road, occurring during the summer. Often a contributing factor is lack of rest. Collision speeds due to the driver falling asleep are often high and the consequences are severe.

Surveys conducted among Finns by the Finnish Road Safety Council indicate that about one in five drivers have sometimes dozed off while driving. An international ESRA (E-SURVEY OF ROAD USERS’ ATTITUDES) survey (Opens in a new window) from 2018 shows that as many as 28.3% of Finns have been so tired while driving during the past month that they had difficulty keeping their eyes open. Out of twenty European countries, only Austria had more people who were equally tired. Driving so tired is generally frowned upon. Only 1% of Finns consider it acceptable to drive so tired that they have difficulties keeping their eyes open.

In a survey conducted by the Finnish Road Safety Council in 2020, 14% of the respondents said they had driven a car during the preceding 12 months while so tired that they were afraid they were going to fall asleep behind the steering wheel. 6 % had dozed off once for at least a second.

Young men’s risk of falling asleep is high

Studies show that the risk of a traffic accident caused by fatigue is high, especially among young men:

  • Young men move a lot at night and often sleep too little. Acute lack of sleep also affects young people more strongly than older age groups.
  • Less driving experience may lead to overestimation of one’s coping ability and to falling asleep.
  • Under group pressure, young people can continue to drive, pressured by friends, regardless of their sleepiness.

If the number of accidents caused by falling asleep is to be reduced, persons under 25 years of age and conscripts are important target groups.

Causes and consequences of fatigue

The most common reason for fatigue is lack of sleep. Fatigue behind the wheel is influenced by the amount and quality of sleep as well as the duration of staying awake. An adult needs an average of 6–9 hours of sleep per day. Other factors, such as illnesses and medication, may also cause fatigue.

Road hypnosis and micro-sleep

In addition to lack of sleep, fatigue may be caused by fog, rain, snow, driving in a queue, long driving stretches and monotonous driving.

Driving alone is dull and causes a decrease in alertness. In a stimulation-free environment, thoughts are prone to wander. Wandering thoughts are referred to as road hypnosis when the driver is not able to recall what happened when driving. It is normal for thoughts to shift from one thing to another, up to 35% of the driving time. In combination with declined alertness, losing focus may, however, cause a risk that things that are important to safety are not noticed.

Another typical and more dangerous phenomenon with decreased alertness is micro-sleep. Tired, the driver falls asleep for a duration anywhere from a few seconds up to one minute, during which they do not take into account what is happening around them. It is also difficult for them to notice that this is happening. In other words, a tired driver who struggles and remains driving has probably already driven beyond their functional capacity without noticing.   

In a Finnish Road Safety Council survey from 2008 (Radun & Radun), almost two-thirds (63%) of those who fell asleep behind the wheel had been in the car alone. Being accompanied by another person is often a factor that prevents the driver from falling asleep. The presence of passengers in the vehicle may also have a negative effect, as young men are vulnerable to pressure from friends to continue driving despite tiredness.

The internal clock regulates the daily rhythm even when driving

We each have an individual sleep–wake rhythm, but mostly it is such that we are tired at night and awake during the day. Fluctuations in attention at different times of the day are one of the main causes of fatigue accidents. Fatigue accidents are most common in the night’s early hours and, for older drivers, during the early afternoon, when alertness is usually slightly reduced.

The driving time alone does not seem to be a decisive risk factor, as 60% of fatal accidents because of falling asleep occur during the first hour of driving. On the other hand, driving time together with the time of day and fatigue before the start of the journey seem to affect the risk of an accident. 

Fatigue accidents occur during free time and working hours

The purpose of the journey is connected to falling asleep while driving. Fatigue accidents occur more during leisure and work-related trips than during shopping and other trips. Shopping trips are generally shorter than other trips and are not done late at night.

When awake, employees are better equipped to work more safely and do more productive work. Therefore, it may be profitable for an employer to invest in measures to increase the alertness of its employees. An accident, if one happens, will have both financial and human costs. In general, it has been found that workers’ exposure to accidents increases with fatigue. It has also been found that working while tired reduces performance and thus causes inefficiency.

Signs of fatigue

Fatigue affects the driver in the same way as alcohol: reduced driving capacity, slower response and more time for detection, solutions and action. Common signs of fatigue include:

  • yawning
  • “sandy” feeling in the eyes
  • eyelids feeling heavy
  • road markings, traffic signs and junctions may not be noticed
  • a feeling of discomfort that may already occur before yawning.

Tools for preventing falling asleep behind the steering wheel:

Because the most effective way to combat fatigue is to rest, driver anticipation in the fight against fatigue starts long before starting to drive.  

Before you travel

  • Sleep at least 6 hours or more on the previous night.
  • Get started in time for longer journeys. This way you will not have to reduce your breaks.
  • If necessary, have a nap during the day before the trip.
  • Think in advance about rest places, and schedule pauses.
  • Avoid driving sick and in poor condition.
  • Do not eat a heavy meal or drink alcohol before driving.
  • Always read carefully the package leaflet of any new medicine and feel its effects before driving.
  • Avoid driving between 1 a.m. and 6 a.m., when the risk of falling asleep is greatest.

While travelling

  • Combine modes of transport as far as possible to drive shorter stretches.
  • Take breaks when driving longer distances.
  • Choose a route with less monotonous driving.
  • Good and lively passenger company helps you stay alert.
  • Change the driver according to alertness.

Although the various alertness guards in cars are not yet very advanced, they can be of help to someone in monitoring alertness.

If you are caught by surprise by tiredness in the middle of a trip despite anticipation, the best way to curb it is to interrupt the journey completely. If that is not possible, drink something with caffeine, such as coffee, and then take a 15–20 minute nap. Caffeine will not take effect until about twenty minutes after ingesting it.

The employer and the work team can also invest in measures that increase the alertness of employees in traffic. Sports and commuting benefits encourage more physical activity for the day. On the other hand, carpooling with colleagues enables driver changes according to the alertness state and the stimulating effect of the company.

Alcohol and fatigue

Being awake for more than 24 hours significantly undermines driving ability and is comparable to having 0.1% alcohol in blood. The performance of the driver decreases and they are unable to regulate their actions effectively to avoid danger. Unlike a drunk driver, a fatigued driver’s logical reasoning remains quite unchanged.
Thus, fatigue does not reduce driving ability as comprehensively as alcohol. Despite this, tiredness is as significant a factor as alcohol is in increasing the risk of accidents. Together, they are particularly harmful. According to studies, a combination of low blood alcohol content (0.03%) and extended periods of staying awake weakens performance more than 0.05% of alcohol alone does. 

Sleep disorders as a risk factor

According to studies, people suffering from sleep disorders or who are sleepier than normal during the day have an increased risk of an accident (e.g. Liu et al. 2018). A few nights of worse sleep do not yet necessarily affect the ability to function behind the steering wheel, but if sleep disturbances are prolonged, it is a good idea to find out what is behind them.

There are effective treatments for many sleep disorders, and when solutions are found, road safety will also improve in addition to the quality of life. Many medicines, including those used for insomnia, reduce the driver’s driving ability for some time. People with sleep disorders should therefore be educated about their higher risk of falling asleep behind the wheel and from the point of view of driving safety.

Sources used include:
Radun & Radun, 2008 and Radun et al. 2015. Summala & Mikkola, 1994