Blue light keeps you alert at the wheel

Last Updated: Tue, Nov 27, 2012 10:40 hrs

London, Nov 27 (IANS) Blue light keeps drivers awake just as effectively as coffee does, especially at nights, says a study based on tests in actual driving conditions.

The findings from the Universite Bordeaux Segalen, France, and Sweden could pave the way for the development of an electronic anti−sleep system to be built into vehicles and minimise fatal collisions.

Sleepiness is responsible for a third of fatalities as it reduces a driver's alertness, reflexes and visual perception. So in a bid to promote road safety, experts are looking to develop an 'embedded' anti−sleepiness device working continuously, the journal Public Library of Science One reported.

Blue light is known to increase alertness by stimulating retinal ganglion cells: specialised nerve cells present on the retina, a membrane located at the back of the eye, according to the Daily Mail.

These cells are connected to the areas of the brain controlling alertness. Stimulating these cells with blue light stops the secretion of melatonin, the hormone that reduces alertness at night.

The positive effect of blue light on night−time alertness has been known since 2005, notably through American research. But they only demonstrated this effect during simple cognitive tasks, such as pushing a button in response to a light stimulus.

To study the efficiency of blue light during night driving, a special LED lamp continuously emitting blue light was installed on the dashboard of an experimental vehicle. Researchers then asked 48 male volunteers (average age 33.2) to drive 400 km on a motorway.

Each driver completed three night drives, spaced out by at least a week, between 1 a.m. and 5.15 a.m., with a 15−minute break halfway through the journey.

During each of the three nights, the volunteers were either exposed to continuous blue light, or given two cups of coffee (one before departure and one during the break).

These either contained 200 mg of caffeine or were decaffeinated, representing a placebo. The researchers found that drivers' sleep was not affected following the journeys with exposure to blue light.

They then analysed the number of times that a driver encroached on road markings (hard shoulder or centre line), reflecting a decrease in alertness.

The results of this test showed that on average, the line was accidentally crossed 15 times by the drivers exposed to blue light, 13 times by those who had had coffee and 26 times by those who had had the placebo.

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