Drowsy Driving


Written by Rebecca Levi

Reviewed by Dr. Michael Breus

Our Editorial Process

Medical Disclaimer: The following content should not be used as medical advice or as a recommendation for any specific supplement or medication. It is important to consult your health care provider prior to starting a new medication or altering your current dosage.

Table of Contents

Drowsy driving, or driving a vehicle while sleepy, is dangerous. It is estimated that drowsy driving causes up to 100,000 crashes and 1,550 deaths each year.

Around 60% of drivers admit to driving while tired and a significant number say that they do so at least once a month. Groups more likely to drive when they are tired include teenagers and young adults, commercial drivers, and individuals with sleep disorders.

Poor quality or insufficient sleep makes it harder to stay alert and attentive behind the wheel. We take a closer look at why drowsy driving is dangerous, which groups are most likely to drive while sleepy, and strategies to reduce drowsiness while driving.

Why Drowsy Driving Is Dangerous

Drowsiness negatively affects many of the cognitive functions that are necessary for safe driving. Drowsiness and fatigue impact a person’s coordination, reaction time, focus, judgment, and memory. As a result, drowsy drivers may lose focus or not brake or swerve in time to avoid a crash.

In addition, people who are tired may unintentionally fall asleep for short periods, a phenomenon called microsleep. Microsleeps can last from less than a second to 30 seconds or more, leaving a driver unable to respond to changes on the road or in their surroundings.

Together these effects are why drowsy drivers are 2.5 times more likely to be involved in a motor vehicle accident, and drowsy driving is associated with 1 in 6 fatal crashes.

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The Causes Behind Drowsy Driving

From sleep disorders to working a night shift, there are many reasons why people drive while tired. Some drowsy drivers may not be getting enough sleep, while others have poor quality sleep that leaves them feeling sleepy the next day.

Experts recommend that adults over the age of 18 get seven to nine hours of sleep every day. Losing a night of sleep or building sleep debt after several nights of insufficient sleep can affect alertness and make driving unsafe. Like insufficient sleep, poor quality sleep can also cause daytime fatigue and cognitive problems that may hamper safe driving.

Certain groups of people may be more likely to drive drowsy and experience the consequences of this dangerous habit.

  • Teenagers and young adults: Numerous factors make drivers under the age of 24 more likely to be involved in accidents related to drowsy driving. Busy schedules and early school start times combined with age-related preferences for staying up late leave many teens sleep deprived.
  • Shift workers: Individuals who work rotating shifts or night shifts may face a variety of sleep problems, including poor quality and insufficient sleep. Shift workers – people who work night or early morning shifts – are at a heightened risk of drifting off while they drive.
  • Commercial drivers: Individuals who drive for a living are at an increased risk of drowsy driving. Around 14% of long-haul truckers average less than five hours of sleep a night.
  • Medical professionals: Long work hours and night shifts put some medical professionals at a heightened risk of drowsy driving.
  • People who have obstructive sleep apnea (OSA): OSA affects sleep quality and causes daytime symptoms like sleepiness. Drivers with OSA are two to three times more likely to be involved in a car crash.
  • People with other sleep disorders: Other sleep disorders, like narcolepsy and chronic insomnia, can cause drivers to fall asleep behind the wheel and increase the risk of accidents.
  • Individuals who take certain medications: Many medications can cause drowsiness, including antihistamines, opioids, benzodiazepines, and muscle relaxants. Combining one of these drugs with alcohol may further increase their sedative effects.

Why Do You Get Sleepy While Driving?

Drowsy driving can be caused by sleep loss or poor quality sleep, but some people may find themselves tired behind the wheel despite getting plenty of rest.

Research suggests that people may become drowsy when they drive at times of the day that don’t align with their circadian rhythm. This may help explain why many accidents occur during the late afternoon or between midnight and 7 a.m, times when people naturally feel more tired.

Long drives can also cause sleepiness because of the effects of task-related fatigue. Task-related fatigue may happen when a person is either over- or under-stimulated while driving. This means that familiar or monotonous drives may lead to drivers feeling sleepy behind the wheel.

Signs You're Too Tired to Drive

Certain signs can signal that you might be too tired to drive safely. Watch out for these warning signs when you’re behind the wheel:

  • Blinking or yawning repeatedly
  • Zoning out or feeling like you’re on autopilot
  • Drifting in and out of your lane
  • Hitting rumble strips
  • Missing exits or turns
  • Trouble focusing
  • Tailgating
  • Irritability or feeling restless

What to Do When You Feel Tired on the Road

If you get drowsy while driving it is best to pull over at a safe, well-lit place such as a rest stop. A brief nap of about 20 minutes may help you to feel more alert.

If you need a longer nap, be sure to give yourself time after waking up so that you don’t drive with sleep inertia, a temporary groggy sensation that occurs after waking. It can make you feel disoriented, slow your reaction times, and make it dangerous to drive. After waking up from a long nap, avoid performing tasks like driving until sleep inertia has worn off.

Caffeine may also help you stay alert if you get drowsy while driving. Slowly sipping one or two cups of coffee, rather than drinking them all at once, may help sustain the effects of caffeine. Caffeine may be even more helpful at improving alertness when combined with a short nap.

Ideally, if you’re feeling tired it is best to avoid driving altogether. Before you hit the road, consider taking precautions to prevent driving drowsy.

  • Sleep well before you leave: The best way to prevent drowsy driving is to get consistent, high quality sleep. Make sleep a priority. If you struggle to get enough rest, consider improving your sleep hygiene.
  • Understand your medications: If you take prescription or over-the-counter medications, learn about the side effects and whether they can cause drowsiness.
  • Treat sleep disorders: Contact a health care provider if you are experiencing symptoms of a sleep disorder such as daytime sleepiness, trouble sleeping, or snoring.
  • Avoid alcohol before you drive: Even if you’re not sleepy, drinking and driving can put you, your passengers, and other people at risk for injury or even death. If you are already tired, drinking alcohol can worsen drowsiness and magnify the effects of medications that make you sleepy.
  • Know the signs of drowsy driving: It can be difficult to gauge your own level of sleepiness, so it’s important to know the signs of drowsy driving. If you notice any of these signs, look for a safe place to pull over.

Improve Your Sleep, Improve Your Focus

Poor sleep habits can contribute to daytime sleepiness and drowsy driving. Improving your sleep hygiene through some simple lifestyle changes may help you to get better rest and feel more alert during the day.

  • Keep a consistent schedule: Try to wake up at the same time each morning and go to bed at the same time every night. Avoid staying up late or sleeping in on weekends, which can disrupt your circadian rhythm.
  • Get enough physical activity: Exercising during the day might make it easier to fall asleep at night. Try to get at least 30 minutes of physical activity each day.
  • Make your bedroom an ideal place to sleep: Keep your bedroom as dark and as quiet as possible. Before you go to bed, remove distracting devices like laptops and smartphones from the room.
  • Avoid bright lights before bed: Artificial light from electronics can tell the brain that it is time to be awake and make it harder to fall asleep. Prevent too much exposure to bright light during the hour before bedtime.
  • Time your caffeine intake wisely: Caffeine is a stimulant that can affect the body for up to eight hours. Drinking caffeinated beverages too late in the day can make it difficult to fall asleep at night, so limit your caffeine intake to the morning hours.

About The Author

Rebecca Levi

Staff Writer, Sleep Health

With a bachelor’s degree in anthropology from Indiana University Bloomington, Rebecca enjoys making accurate, up-to-date health information accessible to all readers. As a freelance writer and editor, she has covered everything from healthcare and experimental music to education. Rebecca lives in Tennessee, where she spends her free time reading, writing fiction, and making music.

  • POSITION: Side Sleeper
  • TEMPERATURE: Cold Sleeper
  • CHRONOTYPE: Dolphin

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