Mercedes-Benz is developing a car that will help put drivers to sleep.The company's "Active Comfort" system uses aromatherapy, lighting and soft music to help a driver to nod off quickly if they pull over to take a power nap.The system was developed with long-haul truck drivers in mind, but the company says it will be rolled out to its passenger car range in the future. The techniques can also be used to keep drivers awake while they're behind the wheel.The aromatherapy feature includes a fragrance-emitting airconditioning system that fills the cockpit with different scents depending on what the driver is doing – menthol to stimulate the senses and keep them alert, or an orange essence when the driver pulls over for a snooze. Mercedes claims a 20 minute power nap can "enhance concentration, reactions and general performance substantially".The system also involves changes to the car cabin to provide better noise insulation and improved fresh air flow. Noise can be tiring for drivers, while if the cabin becomes too warm, it can lead to tiredness and slower reaction times.Crash statistics suggest that fatigue accounts for about 15 per cent of all fatal car accidents and eight per cent of all reported crashes.The NSW Centre for Road Safety's 2010 Crash Statistics report estimated that the risk of having a fatal car accident quadrupled for people driving between 10pm and sunrise.Mercedes says a poor seat position, or a seat that isn't adjusted correctly, can also lead to driver fatigue, so the Active Comfort seats are designed to be more comfortable and feature a massage function to help ease back pain. When the driver pulls over, the seat flatten outs and a cushion can be placed over the steering wheel to act as a foot-rest.The stereo also plays its part in keeping the driver alert. It can play appropriate sleep-inducing songs when the driver is drifting off, or more stimulating tunes when they're waking up. The cabin and exterior lighting systems also work to ensure the driver is more alert.Professor Dietrich Gronemeyer, who was involved in the development of the Active Comfort system, says the main idea is to make the cabin a more comfortable and calming place to be."People who feel relaxed behind the wheel, take the right sort of break in good time and are supported in their seat by innovative technology have a good chance of avoiding the back trouble which has become a 'national ailment'. Stress is a key cause of back complaints, which even afflict the majority of young people today," says Gronemeyer.Another aspect of the system is its fitness function, which acts as a "personal coach" that "provides for well-being, recuperation and subsequent fitness at the wheel". The system includes "expander bands" for resistance exercises, as well as an instructional exercise video."With Active Comfort, Mercedes-Benz is aiming towards a new dimension: your Mercedes-Benz will soon become your personal trainer," a release from the company states. "A tailor-made fitness program ensures long-lasting driver performance. The feeling of well-being is supported both actively and passively by stimulating all of the senses more than in any previous vehicle."Mercedes-Benz says the system will be available on board future production passenger cars.