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Drowsy Driving: Asleep at the Wheel

Tired man behind wheel of carLearn about the dangers of drowsy driving and the importance of good sleep habits.

Falling asleep at the wheel is clearly dangerous, but being sleepy affects your ability to drive safely even if you don't fall asleep. Drowsiness—

  • Makes drivers less attentive.1
  • Slows reaction time.1
  • Affects a driver's ability to make decisions.1

The scope of the problem

Although it may be difficult to attribute a fatal vehicle crash to drowsy driving, the National Highway Traffic Safety Administration estimates that 2.5% of fatal crashes and 2% of injury crashes involve drowsy driving.2 These estimates are probably conservative, though, and up to 5,000 or 6,000 fatal crashes each year may be caused by drowsy drivers.3-5

Who's more likely to drive drowsy?

  • Commercial drivers.
  • Shift workers (work the night shift or long shifts).
  • Drivers with untreated sleep disorders such as sleep apnea.
  • Drivers who use sedating medications.
  • Drivers who do not get adequate sleep.6

How often do Americans fall asleep while driving?

Among nearly 150,000 adults aged at least 18 years or older in 19 states and the District of Columbia, 4.2% reported that they had fallen asleep while driving at least once in the previous 30 days.7 Individuals who snored or usually slept 6 or fewer hours per day were more likely to report this behavior.7

Adults ≥ 18 Years Who Reported Falling Asleep While Driving in Preceding 30 Days—Behavioral Risk Factor Surveillance System, 19 States and the District of Columbia, 2009-2010

Prevent drowsy driving, before taking the wheel

  • Get enough sleep! According to the National Institutes of Health, adults need 7 or 8 hours of sleep a day, while adolescents need 9 or 10 hours.
  • If you have a sleep disorder, make sure to seek treatment.
  • Refrain from drinking alcohol or taking sedating medications before driving.

Drowsy Driving and Alcohol

Cognitive impairment after approximately 18 hours awake is similar to that of someone with a blood alcohol content (BAC) of 0.05%.8-10 After about 24 hours awake, impairment is equivalent to a BAC of 0.10%, higher than the legal limit in all states.10-11

In addition, lower levels of alcohol (below the legal limit) amplify the effects of inadequate sleep.12-13

The warning signs of drowsy driving—

  • Yawning or blinking frequently.
  • Difficulty remembering the past few miles driven.
  • Missing your exit.
  • Drifting from your lane.
  • Hitting a rumble strip.

For more warning signs visit the National Sleep Foundation's Drowsy Driving web site.

If you experience any of these warning signs, pull over to rest or change drivers. Simply turning up the radio or opening the window are not effective ways to keep you alert.


  1. Jackson ML, Croft RJ, Kennedy GA, Owens K, Howard ME. Cognitive components of simulated driving performance: sleep loss effects and predictors. Accid Anal Prev. 2012;50:438.
  2. National Highway Traffic Safety Administration. Traffic Safety Facts Crash Stats: Drowsy Driving. Washington, DC: DOT; 2011. DOT HS 811 4492011.
  3. Masten SV, Stutts JC, Martell CA. Predicting daytime and nighttime drowsy driving crashes based on crash characteristic models. 50th Annual Proceedings, Association for the Advancement of Automotive Medicine; October 2006; Chicago, IL.
  4. Klauer SG, Dingus TA, Neale VL, Sudweeks JD, Ramsey DJ. The Impact of Driver Inattention on Near-Crash/Crash Risk: An Analysis Using the 100-Car Naturalistic Study Data, 2006. Springfield, VA: DOT; year. DOT HS 810 594.
  5. Tefft BC, AAA Foundation for Traffic Safety. Asleep at the wheel: the prevalence and impact of drowsy driving.Washington, DC: AAA Foundation for Traffic Safety; 2010. [PDF - 653KB]. Accessed January 3, 2013.
  6. Stutts JC, Wilkins JW, Scott Osberg J, Vaughn BV. Driver risk factors for sleep-related crashes. Accid Anal Prev. 2003;35(3):321-31.
  7. Centers for Disease Control and Prevention (CDC). Drowsy driving - 19 states and the District of Columbia, 2009-2010. MMWR. 2013;61:1033-7. [PDF - 620KB]. Accessed January 4, 2013.
  8. Williamson AM, Feyer AM. Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occup Environ Med. 2000;57(10):649-55.
  9. Arnedt JT, Wilde GJ, Munt PW, MacLean AW. How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task? Accid Anal Prev. 2001;33(3):337-44.
  10. Dawson D, Reid K. Fatigue, alcohol and performance impairment. Nature. 1997;388(6639):235.
  11. Lamond N, Dawson D. Quantifying the performance impairment associated with fatigue. J Sleep Res. 1999;8(4):255-62.
  12. Howard ME, Jackson ML, Kennedy GA, Swann P, Barnes M, Pierce RJ. The interactive effects of extended wakefulness and low-dose alcohol on simulated driving and vigilance. Sleep. 2007;30(10):1334-40.
  13. Vakulin A, Baulk SD, Catcheside PG, Anderson R, van den Heuvel CJ, Banks S, McEvoy RD. Effects of moderate sleep deprivation and low-dose alcohol on driving simulator performance and perception in young men. Sleep. 2007;30(10):1327-33.