Fatigue Risk Factors

Drowsy Driving Risk Factors: Medical Conditions, Teenagers, Shift Workers

Updated Dec. 14, 2020

Understanding the risk factors that increase your chances of becoming drowsy will help you to make sensible driving decisions. If you know you are at risk, you are more likely to be tuned in to your physical and mental state while driving. When you notice the symptoms of fatigue taking hold, you can take steps to maintain your safety.

Among the groups most at risk from driver fatigue are teenagers, commercial truck drivers, other people who drive as part of their job, shift workers and medical professionals. Let’s find out more.

General risk factors

Some motorists will be more susceptible to fatigue than others. Drivers are more likely to become fatigued when:

  • Driving on their own
  • Driving during hours when they would normally sleep
  • Covering long distances without frequent breaks
  • Traveling on long, straight roads with little stimulation (such as limited access highways and rural roads)
  • Deprived of sleep
  • They are frequent travelers who spend a lot of time behind the wheel

As you may have spotted, commercial truck drivers are exposed to all these risks. In fact, driver fatigue is one of the biggest safety concerns for any person who drives great distances as part of their job.

Though, this does not mean that other motorists are not susceptible to fatigue. If you ever have a long journey planned, try to get plenty of sleep before you set off, travel during the day and take regular breaks every couple of hours.

Medical conditions and driver fatigue

Many disabilities and medical conditions can increase a driver’s risk of experiencing fatigue behind the wheel. Typically, these are conditions that list sleeping problems among their symptoms or are associated with disordered sleep. For instance:

  • Sleep Apnea is a medical condition often associated with heart disease, diabetes and obesity, which causes a person’s breathing to be interrupted as they sleep. This prevents the sufferer from achieving prolonged periods of deep, high-quality sleep and often leads to fatigue during waking hours.
  • Narcolepsy is a neurological condition that interferes with the normal release of the hormones which control sleep. People with narcolepsy generally experience disturbed sleep during the night and may fall asleep uncontrollably during the day.

If you suffer from tiredness and the desire to sleep during the day, it could be that you are affected by one of these conditions without realizing it. Make an appointment with your doctor to get yourself checked out if daytime drowsiness is a persistent problem for you. They will be able to assess you and advise you on whether it is safe to continue driving.

Fatigue in teenage drivers

Surprisingly, teen drivers are more likely to suffer from fatigue while driving than any other age-group. Statistics suggest that in around 55 percent of crashes caused by a driver falling asleep at the wheel, the driver was a person 25 years old or younger. Teenagers may be young and energetic compared to many older people, but studies have shown that they require more sleep to function normally throughout the day and are more susceptible to the adverse effects of sleep deprivation. Here is what we know:

  1. 1

    On average, adults require 8 to 8.5 hours of sleep each night to function well, whereas children and teenagers require around 9.5 hours of sleep.

  2. 2

    The hormones associated with growth and adolescence can disrupt circadian rhythms and cause teenagers to have difficulty sleeping at night, even when they are tired.
    The typical daily schedule of school and other activities then prevents them from catching up on that sleep during the day.

  3. 3

    Teen drivers tend to be more reckless than older drivers.
    They may not notice the effect of fatigue on their body or may choose to ignore it and keep driving.

Remember these points the next time an adult accuses you of being lazy or over-sleeping! In addition to these factors which leave teenagers more susceptible to fatigue, they tend to have a fatigue-inducing lifestyle. While getting insufficient high-quality sleep, most teenagers:

  • Spend roughly 8 to 10 hours a day at school and traveling to and from school. Particularly if they participate in after school activities.
  • Socialize on most days, even when extremely tired
  • Fit in part-time jobs after school or on the weekends
  • Must find time for homework alongside all these other activities

As a teenage driver, you must prioritize safety over convenience and your social life. Having a car makes it easy to get around and this can be a great temptation. Think ahead and avoid driving to see friends or anywhere else, if you are likely to be too tired to drive safely on the journey home.

Fatigue in shift workers

Across the country, around 20 percent of the men and 15 percent of women work in jobs that sometimes require them to work overnight or in the evening. Working when you would usually sleep and attempting to sleep during the day is incredibly disruptive to a person’s circadian rhythm. It is especially problematic when the shifts are irregular, as the worker cannot adapt to a single work-sleep pattern.

Driving home after a night shift is when shift workers are most at risk from fatigue. One rather worrying study found that, during recorded “test” journeys, almost 40 percent of shift workers had a close-call with a car crash.

Medical professionals

Medical workers such as orderlies, nurses and residents are among the most at-risk shift workers when it comes to driver fatigue. Hospital workers must often work shifts of 12 hours or longer, which alternate between night time and day time hours. As mentioned above, it is impossible to adapt to this kind of varied, unpredictable sleep schedule.

Furthermore, the physical, mental and emotional demands placed on a medical professional during an ordinary working day (or night) can be immense. They may have to deal with high-stress, life or death situations and emotionally distressing events, all while being on their feet for many hours with limited breaks.

How does this translate to risk behind the wheel? Well, in one study involving nurses who work 12-hour night shifts, a staggering 95 percent of participants reported having a near-collision experience or being involved in a collision, during a drive home after work.

Would you pass a driving test today?

Find out with our free quiz!


Like the article? Give us 5 points!

Click a star to add your vote

5.0 out of 5 stars based on 3 votes.

Read next

The Consequences of Driving Fatigue
Drowsy Driving 4 of 7

The Consequences of Drowsy Driving

When fatigued, a person cannot perform as well as they would usually during any task. When the task in question is maneuvering a large, heavy metal object that is hurtling along a roadway at speed, persevering despite the effects of fatigue invites death and destruction.

Myths About Driving Fatigue
Drowsy Driving 5 of 7

Drowsy Driving Myths

Driving while drowsy or fatigued is every bit as dangerous as driving under the influence of alcohol. Most drivers are aware of the effect that alcohol may have on their driving ability and would be hesitant to get behind the wheel if they have had a drink, even if they believe they are within the legal BAC limit.

Preventing Driving Fatigue
Drowsy Driving 6 of 7

Preventing Drowsy Driving

Rest is the only cure for fatigue. When you are tired or feeling mentally or physically drained, the only sure way to stay safe is to rest before driving, or not to drive at all. After a hard day at school or a tiring shift at work, people often force themselves to drive, thinking they will rest when they get home.

Medical Fitness for Driving 6 of 9

Physical and Mental Impairments

Your physical and mental condition has a direct affect on your ability to manage and execute multiple tasks while driving. Persons with physical or mental disabilities may lack the necessary skills to operate a vehicle safely.

Medical Fitness for Driving 7 of 9

Illness and Temporary Impairments

Driving ability can be equally as impeded by a temporary physical or mental impairment as it is by ongoing medical conditions and permanent physical disabilities. Every person experiences an illness or injury at some time or another; the fact that you are usually fit to drive does not meant that you are always fit to drive.

Medical Fitness for Driving 8 of 9

Safe Driving and Aging

Getting older does not necessarily mean that you are no longer fit to drive. According to Federal Highway Administration statistics, there are more than 41 million licensed drivers in the United States aged 65 or older. Unfortunately, the physical and mental changes associated with natural aging can adversely affect driving skills and increase the risk of being injured or killed in a car crash.

Medical Fitness for Driving 9 of 9

Carbon Monoxide Poisoning

Unintentional carbon monoxide (CO) poisoning is responsible for roughly 500 fatalities and 15,000 emergency room visits around the United States every year. A large portion of these poisoning cases are caused by motor vehicle exhaust emissions. All drivers must be aware of the dangers of carbon monoxide poisoning and be able to spot the symptoms when it occurs.

Drowsy Driving 1 of 7

The Dangers of Drowsy Driving

Most people accept being tired as a normal part of their hectic, day-to-day lives. Tiredness rarely prevents us from fulfilling our regular daily tasks, such as working, going to school or seeing our friends, so we do not assume that it should stop us from driving to and from these activities. Sadly, driving while fatigued can be a fatal mistake.

Drowsy Driving 2 of 7

The Causes of Fatigue

Being fatigued does not necessarily mean feeling sleepy, though it can lead to that. The term “fatigue” describes a mental and physical state which can occur following a challenging or prolonged activity. A person who is fatigued has a lower-than-normal capacity for work and concentration, while being less capable of completing any task efficiently.