Drowsy Driver Detection Systems Sense When You Need a Break.

By Julie Halpert  |  April 26, 2016

CARS.COM — Bleary-eyed drivers are a danger to themselves and others: The National Highway Traffic Safety Administration says that drowsy driving causes more than 80,000 crashes (almost 220 per day) and 850 fatalities each year. Automakers have been offering technology to alert you when you’re about to nod off, and it’s getting more sophisticated.

Related: Follow These Tips To Avoid Drowsy Driving

Ford’s Driver Alert system is part of a lane keeping assist system. A small, forward-facing camera located behind the rearview mirror keeps track of whether the driver is staying in his or her lane. The system vibrates the steering wheel when it detects that the driver may be swerving, and then it steers the vehicle back into its lane. It is available on the 2016 Ford Fusion Titanium as part of a $1,200 package. Volvo’s Driver Alert Control, offered on all of its models, uses the same technology as Ford’s, sounding an alarm when driving resembles the pattern of a drowsy driver; drivers also get a message to take a break.

Mercedes’ Attention Assist uses a steering sensor that records movements and speed, and determines a baseline for the driver’s behavior. This system comes standard on all Mercedes’ models. The company determined that steering patterns provide the best gauge of drowsiness, since fatigued drivers tend to change their steering behavior and make minor steering errors that they correct immediately. If the system detects erratic steering, it evaluates 70 other parameters, such as how long the driver has been at the wheel. If it determines the driver is drowsy, “drowsiness detected” will appear on the dash with a coffee cup image; there’s also a five-stage bar display that shows the driver’s current attention level and time since his or last stop. Drivers get an audible warning, and a rest-area search can be initiated.

Nissan’s Driver Attention Alert monitors behavior through steering wheel inputs, alerting a drowsy driver with an image of a coffee cup on the dashboard, as does BMW’s Attention Assist, which is offered as standard on the 6 Series and 7 Series. BMW also allows you to customize its warnings, providing an audible warning and coffee-cup icon on the center console; they’ll pop up after an hour into your drive if you set it to “sensitive” and 90 minutes after you start driving if you set it to “normal.”

It’s difficult to create a system that can identify behaviors associated solely with drowsiness, said John Pollard, a human factors expert with Volpe, a Department of Transportation research organization. For example, a driver might wander out of his lane, then jerk the car back not because he’s drowsy, but for other reasons, such as if he’s dealing with his 2-year-old in the backseat. Wind gusts hitting the car also can fool the system into thinking the driver is sleepy. When systems give too many false alarms, many drivers simply choose to turn them off.

Today, safety experts agree that no technology can fully address drowsy driving. The best safeguard against dozing off? Getting a good night’s sleep.