Drowsy Driving - How Big a Problem Is It?

Modern cars are too nice and comfortable and quiet. They make driving too easy and promote drowsiness. Ergonomic seats increase risk. There are fewer drowsy driving crashes on urban roads than on rural roads. Monotonous roadways facilitate don't drive drowsysleepiness but do not cause it.

When a driver is sleepy or fatigued, the combination of slower reaction times, lowered awareness of surroundings, and hundreds of pounds of steel hurtling down a road is hazardous. The transportation community, police, and public health officials refer to these situations as Drowsy Driving. It is a big and underappreciated problem.

It’s hard to get numbers on the scope of the problem because many accidents related to fatigue are not reported as such. Police investigators cannot identify drowsy drivers after an accident. However, all estimates by experts indicate this is a big problem.

Drowsy driving is very much like drunk driving in how it plays out on the roads, if not in how it is treated legally. We have measurable biomarkers for alcohol – a concentration in the bloodstream identifies the driver as legally intoxicated no matter how quick his reaction time is. Further, we have explicit laws against drunk driving. We have neither biomarkers nor analogous laws for drowsy driving. Police may stop a car for general reckless driving, but in general people caught for drowsy driving face less severe penalties than drunk drivers do.

Even accidents that are not explicitly reported as sleep-related may be influenced by drowsiness. An academic study found the "rate of non-sleep ascribed accidents is closely related with sleep propensity."

Wrecks caused by drowsy drivers are often severe because the driver makers little to no attempt to avert the accident. Police investigators often notice the absence of skid marks or other signs of braking as evidence of microsleep. The common description of someone being in a "trance" is a way of saying someone is in microsleep.

Driver and Passenger Awareness

Unfortunately, many do not think about drowsy driving when they consider road hazards. Chances are that you were a little groggy or downright exhausted but got behind the wheel a number of times. But if you’d had too many drinks and knew you were intoxicated, you probably would have handed your keys to someone else to help you get home safely. Why do you choose to be safe in one case and not the other?

“Road has got me hypnotized” - "Radar Love" by Golden Earring.

It’s no surprise there are so many drowsy driving incidents when you consider the number of people who get behind the wheel when they are tired. In response to a survey by the American Automobile Association over 40 percent of adults admit to having fallen asleep at some point while driving. The circadian cycle is a harsh taskmaster. Most drowsy driving accidents happen between midnight and 7 AM.

While transportation industry groups know this is a problem, one noticeable problem is the lack of laws explicitly forbidding drowsy driving.

New Jersey has a law that equates driving when sleep deprived (operationally defined as being awake for 24 hours) with being “reckless,”

But as far as we know, no other jurisdiction in the United States has a similar law. Drowsy drivers can be stopped and arrested or ticketed if they are reckless and police believe them to be dangerous to themselves and other motorists and pedestrians. But unlike drunk driving, there are not laws against

The Numbers on Drowsy Driving

Why it’s so hard to figure out how many crashes and injuries drowsy driving causes every year.

Drivers wake up and become alert when they see the flashing lights of a patrol car behind them or when the car crashes or gets in a near accident. Further, the drowsy driver is often alone in the car so no one is able to tell police the driver was tired. When a driver is both drowsy and drunk, which anecdotally we know happens often, the police probably list alcohol as the cause of a crash even if the police suspect drowsiness.

Self reporting

The AAA Foundation research on drowsy driving found that two out of every five drivers (41 percent) admit to having fallen asleep at the wheel at some point, with one in 10 saying they had done so in the past year. Half of these drivers admitted to falling asleep on high-speed roads.

A Centers for Disease Control survey found 4.2% of respondents admitted to falling asleep at the wheel in the past 30 days. This poll found men more likely to admit to falling asleep than women and older drivers less likely to report sleeping at the wheel.

Best Estimates

The federal government’s National Highway Traffic Safety Administration records 83,000 police-reported crashes are the direct result of driver fatigue each year, and they consider this a conservative number. Those crashes alone cause 37,000 injuries and between 800 and 900 deaths every year. But even the NHTSA acknowledges the true magnitude of drowsy driving is higher. Crashes that happen during the day are generally not included in the 83,000 number. Nor are most incidents involving more than one vehicle.

One reason everyone agrees these numbers are far too low are problems with acknowledging and counting drowsy driving incidents.

The AAA Foundation for Traffic Safety took NHTSA data and produced an estimate of estimated 7 percent of all crashes and 16.5 percent of fatal crashes involved drowsy driving. This equates to a much larger annual death toll exceeding 5000. Scary. The 16.55 of fatal crashes number was in the AAA Foundation’s 2011 study. Their 2014 study estimated 21% of fatal crashes were drowsy driving related.

The Institute of Medicine estimates that drowsy driving causes 20 percent of all US car crashes. The IOM is a division of the prestigious National Academies of Sciences, Engineering, and Medicine and takes a high level look at public health problems.

The CDS summarized several estimates and concluded the number of US fatalities may be 6000 per year.


Related: Regulations

DrowsyDriving.Org - Learn the signs of drowsy driving and countermeasures you can take to avoid excessive risk from driving while sleepy. From the National Sleep Foundation.

Changing Behaviors to Prevent Drowsy Driving and Promote Traffic Safety: Review of Proven, Promising, and Unproven Techniques - From the American Automobile Association

National Highway Traffic Safety Administration

Signs of drowsy driving

Countermeasures to drowsy driving

Responsibility and the drowsy driver

Sleep among shift workers



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