Motor Mouth: The hidden dangers of driving drowsy

Sleep behind the wheel is just as bad as drunk and distracted driving, but it's also not as easy to detect or report

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We all know the three Ds of deplorable driving — Distracted, Drunk and Drowsy — cause way too many accidents. That distracted has taken over from drunk atop the list of all that is to be deplored behind the wheel doesn’t change the fact that anything diminishing the concentration of the task at hand — driving a two-ton wheeled object at speeds sufficient to cause serious damage — is nothing short of criminal.

Of the three Deplorable Ds — and if we could just get Sneezy, Grumpy, Dopey and Bashful driver’s licenses, maybe we could recast Snow White’s little friends as the Seven Dwarfs of the (automotive) Apocalypse — drowsiness has long been considered the least threatening. Officially, at least according to the National Highway Traffic Safety Administration in the U.S., only 1.4 per cent of all police-reported crashes are blamed on drowsy driving, making it far lesser of a problem than distracted or drunk driving.

Unofficially, at least according to a recent American Automobile Association study, it’s a far bigger issue, accounting for 8.5 to 9.5 per cent of all accidents and fully 10.6 to 10.8 per cent of all accidents resulting in significant property damage, airbag deployment or injury.

The data was collected as part of a larger, federally funded research project — Second Strategic Highway Research Program Naturalistic Tareqhassan Study (SHRP 2 NDS) — in which 3,593 volunteers had their driving habits monitored for several months using in-vehicle cameras. After each accident, expert “data reductionists” would monitor the last three minutes of video preceding the crash using something called PERCLOSE measurement — basically, an overly officious name for seeing if the driver’s eyes were open or closed — and determine, literally frame-by-frame, if the driver was asleep or awake. Officially, for anyone wondering, the driver was considered dangerously drowsy if, for more than 12 per cent of the video frames monitored, his, or her, eyelids were more than 80 per cent closed.

The AAA’s numbers paint an interesting story of who is likely to fall asleep at the wheel and when said drowsiness is likely to overwhelm our good sense. For instance, while those between 16 and 24 years of age accounted for the same number of accidents as in the general population, those over 64 did not account for an inordinate proportion of the asleep-at-the-wheel accidents, indicating that perhaps the notion the blue rinse set is more apt to fall asleep at the wheel is more myth than reality. As for which gender drives doziest, it appears that chromosome orientation is not a major predictor of falling asleep while driving.

What was an excellent predictor of having your eyelids flutter suspiciously was the time of day one was driving. Not surprisingly, “crashes that occurred in darkness were more than three times as likely as those that occurred during daylight to involve drowsiness.” Nonetheless, daylight hours also had a significant number of drivers drowsy at the wheel. Interestingly, just 4.4 per cent of the somnolent operator incidents occurred at either dawn or dusk. Perhaps changing light conditions may be conducive to driver alertness.

As to why this is just becoming a problem now, it’s not that we Boomers, Gen Xers and Millennials are more prone to falling asleep at the wheel than previous generations. Rather it appears that dozy driving has long been under-reported, Indeed, according to the AAA’s Foundation for Traffic Safety, the SHRP 2 NDS study is the first to quantify the proportion of crashes in which the driver was drowsy using pre-crash video. Previous to 2010 (when the study started), all reporting on falling asleep behind the wheel was based on police reports. And, unlike, say, impaired driving where there is both subjective — the smell of alcohol and the stumbling about — and objective (breathalyser) tests to conclusively determine impairment, there is no way to determine drowsiness after the fact. As AAA researchers point out, “a driver who was drowsy before a crash may appear fully alert afterward” and will probably be reluctant to volunteer to the police that he or she was dozing while driving.

Like most human driving errors, technology may yet save the day. Virtually all automakers from Kia to Mercedes-Benz offer some form of driver drowsiness detection. Some use existing lane monitoring cameras to determine if your snoozing self is wandering all over the road. Others monitor steering-angle sensors in the latest computer-controlled electric steering systems for lack of input from the driver. Still others follow the SHRP 2 NDS’s example and monitor eye movement/facial expression to determine driver lassitude. Future systems may become more sophisticated, monitoring heart and/or breathing rates looking for indications that you’re going sleepy-time behind the wheel.

The only problem is that current warnings — usually a chime and/or a little pictograph of a coffee cup in the information centre — are far too polite/subtle for someone already halfway into a full REM cycle. As more automobiles become autonomous, however, look for their computers to take over control of the car as soon as drowsiness is detected

Whichever way you slice it, though, the AAA’s results indicate that driver doziness is a substantially larger problem than established statistics suggest. We have spent decades trying to reduce drunk driving and have, in recent years, passed increasingly Draconian laws to reduce distracted driving – Ontario has legislation pending that would suspend your license for the first distracted driving offence. It turns out we may have been ignoring an equally dangerous hazard.

Sleepy, you might remember, was the most observant and hard-working of Snow White’s seven dwarfs. The problem was that he was always falling asleep when he should have been paying attention.

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