Munich/Schwalbach - Car designers are currently probing new ways to avoid one of the most dangerous hazards of night driving - drowsiness and falling asleep at the wheel.
Many car crashes can be traced back to such momentary losses of concentration, a sudden sleepiness which can easily cause a motorist to veer onto the wrong side of the road with potentially fatal consequences.
To combat this phenomenon, an increasing number of new vehicles are being fitted with a bleeper that can alert the driver before he or she succumbs.
Now scientists are looking into a new way to fight grogginess at the wheel using high-intensity interior lights which prevent the driver from getting tired in the first place.
Developing a workable version to be fitted to today's cars is not easy however. US Scientists at the Rensselear Polytechnic Institute (RPI) in Troy, New York State are currently evaluating how blue light affects daytime and nighttime awareness.
Tests have show that exposure to a certain wavelength of blue light generated by light emitting diodes (LEDs) stimulates the human visual system and increases attention. Scientists now face the task of putting this knowledge to practical use.
One idea is to incorporate the cool blue lights into the interior lighting systems of modern cars. They could also be installed at refresher rooms in motorway service areas, enabling tired drivers to take a "shower of light" before continuing a journey.
The positive effects of blue light have been known for some time. According to Thomas Kantermann of the Ludwig-Maximilian University in Munich, this type of light stimulates the body's circadian system which controls periods of waking and sleep.
"Light is one of the most important body synchronizers. We know the body's circadian or biological clock responds best of all to blue."
This comes about because blue light waves are very similar to natural daylight. Meanwhile experiments show that it is possible to "re-programme" a person's body clock by increasing the concentration of blue in artificial light, explained Kantermann who is a chronobiologist, a doctor who specializes in the effect of time on the body and its natural rhythms.
The blue light tricks the body into thinking it is broad daylight and in theory the effect could be used to boost a driver's level of night time concentration. "Anything which stimulates the body clock raises attention levels," said Kantermann.
Those exposed to such blue light generally feel better and more attentive although some experts claim that a flash of blue light at the petrol station would not be enough to produce a beneficial effect.
The effectiveness of blue light depends on how a particular person reacts to it and since everybody's body clock is different, the length and intensity of LED light exposure is as important as the time at which it is applied," said Kantermann. It also depends on how much light a person has been exposed to beforehand.
The German scientist warns that light therapy does involve risks too. "It really is amazing what you can do with a lamp. You can completely disorientate people," said the chronobiologist.
Tests have shown that it is possible to significantly alter the reaction of test candidates to light stimulus and effectively transform them into night owls, said the expert.
One possible drawback is that a burst of light exposure or "shower" might only serve to delay the tiredness, leading to heightened fatigue afterwards.
The high intensity of light needed for a "wake-up light" could also end up distracting a motorist from the task of driving the car after dark.
This problem cropped up when developers at Volkswagen tried out a so-called "vigilance light" which simulated a sunny blue sky and normal daylight light levels.
According to spokesman Hartmuth Hoffmann at VW's headquarters in Wolfsburg the use of such lamps made it hard for drivers to adjust from daytime to nighttime driving.
"The light was too light for night driving and the desired effect did not occur," said Hoffmann. The research project was later abandoned.
Over at automotive component maker VDO Automotive in Schwalbach in Hesse state, researchers have been following the progress of the "wake-up light" project with interest.
There are however no current plans to incorporate the findings into the firm's range of dashboard and interior lighting, said light expert Heinrich Noll.
VDO Automotive places the emphasis instead on instrument and dial displays which are easy to read and which do not place a strain on the motorist's eyes at night. This in itself helps to combat any grogginess.
Noll believes that successful nighttime lighting in a vehicle should consist of two colours only to avoid confusing the driver. The interior and instrument lighting should create a unified and relaxing ambience, with the second colour reserved for instruments which signal impending hazards. (dpa)