Scientific studies conclude that around 25 percent of all serious motorway accidents are down to driver drowsiness, meaning that drowsiness causes more road accidents than drink-driving.

The risk of falling asleep momentarily is at its greatest on long-distance journeys in the dark or in unchanging conditions because this is when drivers are most
likely to suffer a lapse in attention. The sheer monotony further heightens the risk of falling asleep at the wheel. Studies show that, after just four hours of non-stop driving, drivers' reaction times can be up to 50 percent slower. So the risk of an accident doubles during this time. And the risk increases more than eight-fold after just six hours of non-stop driving!

The newly developed ATTENTION ASSIST system sees Mercedes-Benz continuing to adopt a practically-oriented stance towards accident avoidance. A stance which has already lead to a proven improvement in road safety thanks to developments such as the Electronic Stability Program (ESP®) and Brake Assist.

ATTENTION ASSIST observes the driver's behaviour and, at the start of every trip, produces an individual driver profile that is then continuously compared with current sensor data. This permanent form of monitoring is important for
detecting the floating transition from awakeness to drowsiness and for warning the driver in plenty of time. The system is active at speeds of between 80 and 180 km/h.

As well as the speed, lateral acceleration and longitudinal acceleration, the Mercedes system also detects steering wheel movements, use of the turn indicators or pedals and certain control inputs, not to mention external influences such as side winds or road unevenness, for example. Observation of steering behaviour has proven to be extremely meaningful as drowsy drivers find it difficult to steer a precise course in their lane. They make minor steering errors that are often corrected quickly and abruptly. Intensive tests carried out by the Mercedes engineers, involving more than 550 drivers, show that this effect occurs at a very early stage when drowsiness kicks in – often before the dangerous situation in which the driver falls asleep momentarily.

At the heart of this Mercedes system is a highly sensitive sensor which allows extremely precise monitoring of the steering wheel movements and the steering speed.

Based on these data, ATTENTION ASSIST calculates an individual behavioural pattern during the first few minutes of every trip. This pattern is then continuously compared with the current steering behaviour and the current driving situation, courtesy of the vehicle's electronic control unit. This process allows the system to detect typical indicators of drowsiness and warn the driver by emitting an audible signal and flashing up an unequivocal instruction on the display in the instrument cluster: "ATTENTION ASSIST. Break!"