Crash Risk Doubles with Sleep Deprivation

One to two hours can make a difference when it comes to sleep.  A new study out of the AAA Foundation for Traffic Safety has found that drivers who get one to two hours less than the recommended seven to eight hours each night double their risk of accident.  About 35% of American drivers get less than the recommended amount of sleep, according to the Centers for Disease Control and Prevention.

AAA warns that getting less than the recommended number of hours for sleep may come with deadly consequences, especially since drowsiness is reported in one out of every five fatal crashes every year in the U.S. alone.

Executive Director at the AAA Foundation for Traffic Safety, Dr. David Yang, reports that losing sleep, especially getting less than five hours every night, has a comparable risk to someone who drives drunk.  You cannot lose a couple of hours of sleep and expect not to have consequences, Dr. Yang notes.  Sleep loss means you cannot safely be able to function behind the wheel.

The report from AAA, Acute Sleep Deprivation and Risk of Motor Vehicle Crash Involvement, compared drivers who got seven hours of sleep and those who got four to five hours of sleep each night.  They found that those who got fewer than five hours of sleep quadrupled their risk of crash compared to those who got the recommended amount of sleep.  The National Highway Traffic Safety Administration gives the same risk for someone driving over the legal limit of alcohol.

When compared to drivers who got enough sleep, those who were sleep deprived had progressively increased risk of crash, with the following findings noted from the AAA Foundation:

  • Four hours of sleep or less were at 11.5 times the crash risk
  • Four to five hours of sleep were at 4.3 times the crash risk
  • Five to six hours of sleep were at 1.9 times the crash risk
  • Six to seven hours of sleep were at 1.3 times the crash risk

About 97% of AAA surveyed drivers viewed drowsy driving as a completely unsafe and unacceptable behavior; however, one in three admit to drowsy driving at least once a month, admitting they could hardly keep their eyes open behind the wheel.

Jake Nelson, AAA director of Traffic Safety Advocacy and Research, notes that many of us sacrifice sleep for our careers and lifestyles, but maintaining a healthy work-life balance is necessary for safety and health.  Not creating a healthy bedtime routine and getting adequate sleep means you are putting yourself and others at risk while driving.

Symptoms to look out for with drowsy driving include:

  • Difficulty keeping your eyes open
  • Lane drifting
  • Not remembering the last few miles

However, it is notable that more than half the drivers that were involved in sleepiness-related crashes did not report experiencing any symptoms before falling asleep behind the wheel.  Researchers and experts at AAA urge drivers not to wait for physical symptoms to occur, but instead to prioritize their sleep as a preventive measure.  For those who take longer road trips, they should:

  • Take scheduled breaks every two hours or 100 miles
  • Avoid heavy meals; eat several smaller meals throughout the day
  • Travel during normal wake times
  • Avoid taking any medications that may cause drowsiness or impairment
  • Travel with someone who is awake and alert during driving

A total sample of 7234 drivers involved in 4571 crashes was analyzed in this AAA Foundation report.  All the information came from the National Motor Vehicle Crash Causation Survey from NHTSA, which included a sample of reported crashes involving at least one party sent for emergency medical treatment and at least one vehicle towed from the scene.


Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, cooking, and reading.


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