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A Nissan engineer demonstrates his company's driver alert system in Tokyo in 2008. See more car safety pictures.

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Will your next car wake you up when you fall asleep at the wheel?

There are few things more unsettling than seeing a large tractor-trailer drift gently and then suddenly swerve back into its lane. Driving down the highway at night, your car filled with sleeping family members, you'll likely ease off the accelerator and allow the distance to grow between you and the semi -- or hit the gas and leave it far behind.

Sleepy truck drivers have been an issue for about as long as commercial trucking has been around. They operate large, lumbering vehicles that could take out several cars at once. Due to the rigs' size, they can't be maneuvered as quickly as cars or light trucks. And truck drivers simply drive more than other drivers. They may push themselves beyond the limits demanded by the sleep cycle -- the pattern of sleep and wakefulness -- in order to deliver their haul and get home.

The problem posed by snoozing truckers has prompted a glut of studies on how to address the issue of nodding off behind the wheel. These studies have led to regulation and new technologies. The federal government mandates that truckers can drive for no more than 12 hours before taking a mandatory 10-hour break [source: Dallas Morning News]. Researchers have created inventions to keep truckers awake, like LED lights that simulate morning light to trick truckers' circadian rhythm -- the body's natural clock -- into thinking it's morning and time to wake up [source: ScienceDaily].

While truckers make great subjects for tests that aim to solve the problem of drowsy drivers, they're hardly the only ones who fall asleep at the wheel. Auto safety researchers have come up with some clever ways to rouse sleepy drivers in passenger vehicles, too. So will your next car wake you up when you fall asleep? That's a real possibility, especially if you're planning on shelling out the money for a luxury car when you buy your next automobile.

What high-tech systems aim to keep you bright-eyed and bushy-tailed when you drive? Find out on the next page.

Whoa there. Forget about the trucker falling asleep. You look like you could use some rest yourself.

Larry Dale Gordon/Getty Images

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Drowsy Driver Alert Systems

In the opinion of Claes Tingvall, head of the highway traffic safety department in Sweden (the land of Volvo, decades-long leader in car safety), the auto industry is in the throes of a car safety revolution. Safety hasn't been such a priority since the advent of seatbelts in the 1960s [source: Reuters]. Auto companies like Volvo, Saab, Nissan and Mercedes-Benz have been studying sleep-deprived drivers in simulated driving scenarios to find the best way to wake up drowsy drivers.

From these tests, Volvo has created the Driver Alert system. If the car concludes that the driver is drowsing (more on that later), it issues an audible alarm, and an icon depicting a cup of coffee flashes on the instrument panel [source: Edmunds]. Saab has a similar arrangement. The company's Driver Attention Warning System uses a voice alarm: If a driver is nodding off, the car announces "You are tired," followed by "You are dangerously tired! Stop as soon as it is safe to do so!" The driver's seat also vibrates to help rouse him or her [source: Forbes Autos].

Second-generation drowsy driver alert systems will be even more high-tech. Independent companies are perfecting alerts that can safely bring a driver to wakefulness. Additional measures, like emitting puffs of air on the back of a dozing driver's neck, vibrating steering wheels and automatic steering that takes over and gently guides you back into your lane when you drift, may all be found in driver alert systems soon [source: New York Times].

Wait, wait, wait: How can a car tell when you're nodding off? Researchers are tweaking already extant car safety technologies and applying them in new ways. For example, blind-spot warning systems in today's digital cars keep an eye out for other vehicles in places you can't see. They also analyze your car's relation to its lane and whether your turn signal's on or not. Add to this system automatic steering that kicks in when you drift, and you've got part of a drowsy driver alert system.

Soon, you and your car will be better acquainted than ever before. From the moment you first purchase your 2009 Mercedes-Benz and begin driving it, the onboard computer analyzes your particular driving traits to create a profile. It matches this profile against your current driving situation -- like how you're steering, how long you've been driving at a stretch and what time it is. If your behavior doesn't match your profile, the car can tell that something's not quite right and sends you an alert. So whether you're nodding off, distracted or taking chances on the road, the alert should make you more mindful when you're behind the wheel [source: Gizmag]. What's more, the car creates a profile for each driver [source: Motor Authority]. Volvo's system is similar; its cars also analyze how you're driving -- like your proximity to cars ahead of you and whether you're maintaining your lane -- to determine wakefulness.

Saab's onboard computer uses facial recognition software to determine if you're drowsing. Night vision cameras trained on your face analyze slackening facial muscles, your blinking patterns and how long your eyes stay closed between blinks. Once it concludes you're no longer awake, the system kicks in to rouse you from your dangerous slumber [source: Forbes Autos].

But until you buy a new car with one of these systems, you should probably stop for coffee before you nod off.

For more information on high-tech cars and other related topics, visit the next page.

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Lots More Information

Related HowStuffWorks ArticlesMore Great LinksSources
  • Francis, Erica. "A wake-up call behind the wheel." Forbes Autos. November 26, 2007. http://www.forbesautos.com/news/features/2007/sleeping-at-the-wheel.html
  • Gaskin, Max. "Blue LEDs to reset tired truckers' body clocks." New Scientist. March 18, 2008. http://technology.newscientist.com/article/dn13491-blue-leds-to-reset-tired-truckers-body-clocks.html
  • LaFleur, Jennifer. "Poodle-toting trucker says diesel runs in her veins." Dallas Morning News. December 11, 2006. http://www.dallasnews.com/sharedcontent/dws/news/texassouthwest/stories/121106dntswtruckpistol.3426397.html
  • Moran, Tim. "Keeping tired drivers alert, with no snooze button." New York Times. March 11, 2007. http://www.nytimes.com/2007/03/11/automobiles/11WAKE.html
  • "Electronic warning system to keep drivers alert." Continental Corporation. September 19, 2006. http://www.vdo.com/press/releases/commercialvehicles/2006/sv-200609-005-en.htm
  • "Lane departure warning systems help drowsy drivers avoid crashes." Science Daily. October 17, 2006. http://www.sciencedaily.com/releases/2006/10/061016121708.htm
  • "Mercedes Attention Assist nears production." Motor Authority. Decmber 10, 2007. http://www.motorauthority.com/news/safety/mercedes-attention-assist-nears-production/
  • "New Mercedes-Benz system warns sleepy drivers." Gizmag. December 12, 2007. http://www.gizmag.com/new-mercedes-benz-system-warns-sleepy-drivers/8497/
  • "Tech watch: Volvo's driver alert control finally ready for prime time." Edmunds. August 30, 2007. http://www.edmunds.com/insideline/do/News/articleId=122411
  • "Volvo's 2020 vision: The injury-proof car." Reuters. May 1, 2008. http://www.msnbc.msn.com/id/24406445/