Sleep Disorders Effects Driver Fatigue

Driver fatigue is a physiological and psychological condition that significantly affects driving ability and judgment. Sleepy driving impairs alertness and response time and increases the risk of accidents. Learn how to recognize the signs of driver fatigue and get tips on how to avoid driving while sleepy.

Symptoms of Driver Fatigue

Symptoms of tired driving include feeling sleepy, groggy or exhausted. A person may yawn frequently, feel irritable or have difficulty concentrating. The driver’s eyes may feel strained, sore or tired. Driver fatigue causes sleepy drivers to have problems steering, miss road signs, ignore lanes or experience short bursts of microsleep (a shift from waking to sleep lasting only a few seconds).

The inability to recognize the dangers of fatigue and driving is common. Warning signs of driver fatigue include:

  • Daydreaming
  • Driving over the center line
  • Excessive yawning
  • Feeling impatient
  • Heavy eyes
  • Slow reactions
  • Stiffness.

Not being able to remember the last few seconds or minutes of driving is a clear warning sign of tired driving, and indicates incidents of microsleep.

Who Suffers from Driver Fatigue?

Fatigue and driving are concerns for anyone who drives. Anybody lacking proper rest runs the risk of sleepy driving, but certain groups experience fatigue and driving more often than others.

The National Highway Traffic Safety Administration (n.d.) reports that people under age 30 account for two-thirds of sleepy driving accidents, although they represent only 25 percent of drivers. Men are more likely to drive while sleepy than women.

Sleepy driving is common among long-distance truckers. Shift workers also have high rates of driver fatigue, as do people who suffer from sleep disorders such as sleep apnea or narcolepsy.

Sleepy driving accidents are more common in rural areas than urban centers, although sleep-related accidents can also occur in cities.

High-Risk Times of Day for Fatigue and Driving

Energy levels drop at certain times of day due to the body’s circadian rhythms. Circadian rhythms act as an internal clock and control normal sleep/wake cycles. Circadian rhythms cause drops in energy between 10 p.m. to 6 a.m. and 2 p.m. to 4 p.m. People driving during these hours are at an increased risk of driver fatigue.

Preventing Sleepy Driving

Rest and sleep are the only cure for driving while sleepy. People who are affected by tired driving should avoid driving and find a place to rest.

You can minimize the risk of driving while sleepy with the following suggestions:

  • Avoid alcohol, large meals and medications that cause drowsiness.
  • Establish a realistic driving plan that does not require long periods of driving without a good night’s sleep and healthy breaks.
  • Stay hydrated, get a lot of fresh air and incorporate environmental stimuli when possible (music, conversation, etc.). Remember, however, that too much stimuli can be distracting.
  • Share the driving whenever possible.
  • When driving, take a break at least every two hours.

The only reliable defense against driver fatigue is rest. This means uninterrupted sleep for at least six to nine hours each night and watching for signs of fatigue while driving.


Australian Academy of Science. (2002). Driver fatigue – An accident waiting to happen. Retrieved January 26, 2007, from:

National Highway Traffic Safety Administration. (n.d.). Drowsy driving and automobile crashes. Retrieved October 6, 2010, from POPULATION GROUPS.

Roads and Traffic Authority. (2008). Driver fatigue. Retrieved October 6, 2010 from

Smart Motorist. (n.d.). Driver fatigue is an important cause of road crashes. Retrieved October 6, 2020, from