Blue Light in Car Keeps You Alert Behind the Wheel
Researchers from the Universite Bordeaux Segalen, France, and their Swedish colleagues demonstrated that constant exposure to blue light is as effective as coffee at improving night drivers' alertness.
The findings could pave the way for the development of an electronic anti-sleep system to be built into vehicles, which could be crucial in preventing fatal crashes, the Daily Mail reported.
Sleepiness is responsible for one third of fatalities on motorways as it reduces a driver's alertness, reflexes and visual perception.
Apart from stopping to take a nap, drinking coffee remains the best preventive measure.
So in the interest of road safety purposes, experts are looking to develop an "embedded" anti-sleepiness device working continuously.
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.
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 researchers' findings were based on tests conducted in real driving conditions.
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.
The researchers then asked 48 male volunteers (average age 33.2) to drive 400km on a motorway.
Each driver completed three night drives, spaced out by at least a week, between 1am and 5:15am, 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.
Continuous exposure to blue light while driving therefore appears to be as efficient as coffee for fighting sleepiness at the wheel, as long as this light does not hinder the driver.
However, eight of the 48 volunteers found that they were dazzled by the blue light and could not do the test.
The study has been published in the journal PLoS One.