Ambient blue light resets tired workers' body clocks
Tedious work during the “wrong” hours of the body’s biological clock — think truckers who drive through the night, or security officers monitoring CCTV screens during the graveyard shift — often leads to drowsiness; falling asleep behind the wheel or in front of a security monitoring screen can lead to catastrophes; researchers develop a way to “fool” the brain to think it is morning
What do truck drivers and security officers sitting in front of security TV monitoring screens at a command center have in common? Two things: Their work is tedious, and dozing off may lead to catastrophe. Now there is a solution (the initial experiments involved truckers): Eerie blue LEDs in truck cabs and truck stops could be the key to reducing accidents caused by drowsy drivers, say researchers. They say bathing night drivers in the right light can increase their alertness by resetting their body clocks. The scientists at Rensselaer Polytechnic Institute, New York, are testing blue LEDs which shine light at particular wavelengths that convince the brain it is morning, they say, resetting the body’s natural clock. This could help reduce the number of accidents that occur when people drive through the night. Nearly 30 percent of all fatal accidents involving large trucks in the United States happen during the hours of darkness, according to a recent report by the Federal Motor Carrier Safety Administration, while fatigue causes half of all truck accidents in the early hours on UK motorways.
“The concept of using light to boost alertness is well established [in other areas],” says Mariana Figueiro, coauthor of a new white paper published by the institute’s lighting research center. “Translating that understanding into a practical application is the next challenge.” Drivers could take 30-minute “light showers” in truck stops fitted with similar lights, or the lights could be fitted into truck cabs. Figueiro is currently investigating how the blue light affects daytime alertness of sleep-deprived and nonsleep-deprived subjects. “These findings will also be applicable to transportation applications, since the accident rates during the afternoon hours are still higher than in the morning hours,” says Figueiro. Results so far show a clear effect on the brain activity of test subjects of both kinds, she adds. “After 45 minutes there is a clear effect,” says Figueiro. “You start to see a beautiful increase in brain activity in the 300 milliseconds response, which is a measure of alertness.” The current test box emits diffuse light at 470 nanometers, with an intensity of 40 lux when measured at the eye.
Figueiro plans experiments on a driving simulator using different light spectra, of 450 and 470 nm, and intensities of 2.5, 5 and 7.5 lux, to see which combination works best without obscuring the driver’s view of the road.
An alternative is to build goggles with blue LEDs for the driver to wear before setting off. Figueiro is already designing such equipment for people with Alzheimer’s that will change their circadian rhythms to reduce their nocturnal alertness and help them to sleep at night. Car manufacturers already market systems to warn or wake drowsy drivers. They use measures of eye movements, blink rates, or small steering-wheel movements to tell if a driver is losing alertness. Preventing drowsiness in the first place would be more effective. Jim Horne, director of the sleep research center at U.K.’s Loughborough University says changing the body’s clock is possible, but difficult in short periods. “Shifting it by eight hours takes at least 10 days, and very few people are capable of doing that,” he says.
