The dangers of drowsy driving are severely underestimated. A new analysis of National Highway Traffic Safety Administration crash data estimates drowsy driving is a factor in nearly one in six fatal crashes. “Just like drugs and alcohol, sleepiness can impair important functions behind the wheel like response time, awareness and judgment. Many people think they can force themselves to stay awake, but dozing off behind the wheel, even for a few seconds, is plenty of time to drive off of the road or over a centerline” 2. Fatalities and injuries are more likely to occur in motor vehicle crashes that involve drowsy driving compared with non drowsy driving1 and driving while drowsy was a contributing factor for 22 to 24% of the crashes and near-crashes respectively4.

Drowsiness essentially begins the moment measures need to be taken against it. Being drowsy may be equated to drunk driving with reduced driving functionality and reaction time3. Although it is clear that falling asleep while driving is dangerous, drowsiness impairs driving skills even if drivers manage to stay awake. Drowsiness slows reaction time, makes drivers less attentive, and impairs decision-making skills3.

Forty-one percent of drivers admit to having “fallen asleep or nodded off” while driving at some point in their lives, including 11.0% within the past year and 3.9% in the past month. More than one in four drivers admits to having driven when they were “so sleepy that [they] had a hard time keeping [their] eyes open” within the past month10.

Sixteen to 24 year old drivers were the most likely to report having fallen asleep while driving within the past year 10. Men were much more likely than women to report having ever fallen asleep while driving (52.2% vs. 30.1% respectively), and to report having done so within the past year (14.0% vs. 8.1% respectively) 10.

Sleep-related crashes are more likely to happen at night or during the mid-afternoon: more than one in four (26.1%) of those who reported having fallen asleep while driving in the past 12 months reported that they had done so between the hours of noon and 5 PM; as many as those who reported having done so between midnight and 6 AM (24.7%) 10. Crashes that occurred on Saturday or Sunday were over twice as likely as crashes that occurred during the week to have involved a drowsy driver10.

Three of five (58.8%) who reported having fallen asleep while driving in the past 12 months reported that they had been driving for less than an hour before they fell asleep, whereas one in five (20.6%) reported having been driving for 3 hours or longer. Only 27.7% reported that they realized before they started driving that they might have difficulty staying awake; 71.0% reported having felt awake enough to drive10. Drivers travelling alone were 81% more likely than drivers with passengers to have been drowsy 10.

The results of this analysis indicated that drowsy driving was associated with other sleep-related characteristics. Adults who reported frequent insufficient sleep, a daily sleep duration of ≤6 hours, snoring, or unintentionally falling asleep during the day reported drowsy driving more frequently than those who did not report those characteristics4.

Warning signs of drowsy driving include frequent yawning or blinking, difficulty remembering the past few miles driven, missing exits, drifting from one’s lane, or hitting a rumble strip5.

The only safe thing for drivers to do if they start to feel tired while driving is to get off the road and rest for 20 minutes. Resting between 30 minutes to an hour has shown a decrease in performance and an increase in drowsiness. Drivers should ensure that they get enough sleep (7–9 hours), seek treatment for sleep disorders, and refrain from alcohol use before driving7Techniques to stay awake while driving, such as turning up the radio, opening the window, and turning up the air conditioner, have not been found to be effective7.


  1. Chapman, D. P., Presley-Cantrell, L. R., Croft, J. B., Roehler, D., & Wheaton, A. G. (2013). Drowsy driving — 19 states and the District of Columbia, 2009–2010. Morbidity and Mortality Weekly Report61(51), 1033-1037. doi:
  2. “Drowsy Driving.” AAA Foundation for Traffic Safety. N.p., Jan. 2013. Web. 4 Mar. 2013. <;.
  3. Jackson ML, Croft RJ, Kennedy GA, Owens K, Howard ME. Cognitive components of simulated driving performance: sleep loss effects and predictors. Accid Anal Prev 2013;50:438–44.
  4. Klauer, S. G., Dingus, T. A., Neale, V. L., et al. (2006). The impact of driver inattention on near crash/crash risk: An analysis using the 100-Car Naturalistic Driving Study data. Report No. DOT HS 810 594. Washington, DC: National Highway Traffic Safety Administration.
  5. Knipling RR, Wang J-S. National Highway Traffic Safety Administration. Crashes and Fatalities Related to Driver Drowsiness/Fatigue. Washington, DC: US Department of Transportation, National Highway Traffic Safety Administration; 1994. Available at 
  6. Masten, S. V., Stutts, J. C., & Martell, C. A. (2006). Predicting daytime and nighttime drowsy driving crashes based on crash characteristic models. 50th Annual Proceedings, Association for the Advancement of Automotive Medicine, October, Chicago, IL.
  7. NCSDR/NHTSA Expert Panel on Driver Fatigue and Sleepiness. Drowsy driving and automobile crashes. Washington, DC: National Highway Traffic Safety Administration; 1998. Available at
  8. Pack AI, Pack AM, Rodgman E, Cucchiara A, Dinges DF, Schwab CW. Characteristics of crashes attributed to the driver having fallen asleep. Accid Anal Prev 1995;27:769–75.
  9. Stutts JC, Wilkins JW, Scott Osberg J, Vaughn BV. Driver risk factors for sleep-related crashes. Accid Anal Prev 2003;35:321–31.
  10. 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.
  11. Wierwille, W. W., and Ellsworth, L. A. (1994). Evaluation of driver drowsiness by trained raters. Accident Analysis and Prevention, 26(4), 571-578.

A Rocket Scientist Explains How a Sleep Study Can Change Your Life

A Rocket Scientist Explains How a Sleep Study Can Change Your Life

Once upon a time, before medical science started nosing around your bedroom, snoring was a nocturnal annoyance and little more. Sawing logs in the wee hours, while the bane of spouses and significant others, wasn’t a health concern – just cause for housemates to wear ear plugs…

Dental screening that could save your life

Dental screening that could save your life

Getting a poor night's sleep? Ask your dentist if you grind your teeth -- a red flag for sleep apnea.

We all know about the importance of sleep, and we know we should be getting more of it. When we wake up exhausted, drag ourselves to work or hit that afternoon slump, we blame ourselves: “Should have gotten more sleep last night.”

But instead of “Did I get eight hours?” we should be asking ourselves, “How well did I sleep?” We tolerate feeling exhausted during the day, but it’s actually not normal to feel tired or sleepy when you wake up.