Blinded by brighter headlights? It’s not your imagination.
By Christopher Mele
The light-emitting diodes in the headlights of oncoming traffic became so intense for Shawn DeVries that he started habitually closing his left eye and keeping his right one open as he drove.
That was in 2019. Since then, he said, his right eye “hurts so bad, sometimes I just want to pop it out.” He said he developed intermittent pain and a light sensitivity that has affected his social life and his driving habits.
DeVries, 48, of Doon, Iowa, said he does not have diabetes or high blood pressure, which could affect his vision, nor does he engage in risky behavior that could harm his eyes.
“I didn’t weld without a helmet,” he said. “I didn’t stare at the sun with binoculars.”
Advances in lighting technology have improved nighttime driving for many, but the introduction of brighter lights that also sit higher on SUVs and pickups has given rise to widespread criticism that headlights have become overpoweringly intense.
“If you’ve not been affected by them, you will be,” DeVries said, referring to LED headlights. “You wait. You’re next. It’s only a matter of time.”
A lighting evolution gives rise to complaints
DeVries is not imagining things. Matt Kossoff, chief product officer of The Retrofit Source, an Atlanta-based distributor of lights for cars and trucks, said headlights had “absolutely gotten brighter.”
“Sealed-beam” headlights were used from the 1950s through the 1980s, and generally offered poor light output. Halogens, with tungsten filaments and better output, appeared in the late 1980s and early 1990s.
High-intensity discharge lights, which cast a bright glow that approximates the spectrum of daylight, came in the late 1990s and early 2000s. In the 2010s, LEDs became popular because they were longer-lasting, energy-efficient and perceived by automakers as sexy and modern.
But they also prompted complaints that they were too much of a good thing. There is even a Facebook group and an online petition dedicated to banning blinding headlights.
“The balance we are always trying to strike is what is the mitigation and what are the unintended consequences?” said Eric Kennedy, associate professor of biomedical engineering at Bucknell University in Lewisburg, Pennsylvania.
The trend toward improved headlight illumination has been fueled in part by manufacturers seeking higher safety ratings from the Insurance Institute for Highway Safety, Kennedy said.
When the institute, an independent, nonprofit research group, released its first headlight ratings in 2016, only one headlight system of more than 80 that were evaluated received a “good” rating. As of March, more than a quarter of those tested received such a rating, the institute said.
Complaints about headlight glare are not new, and date back at least 20 years.
After the National Highway Traffic Safety Administration sought comments from the public in 2001 about glare, it issued a report that said the 4,000 responses it received “was larger than those that NHTSA received on other safety concerns.”
About 30% of respondents said they had experienced “disturbing” nighttime headlight glare from oncoming traffic or from cars whose lights appeared in their rearview mirrors. The report described that percentage as a “sizable number” that “cannot be ignored.”
It was not just older drivers complaining, either.
The report said 11% of those who rated oncoming glare as disturbing were older than 65, and 45% were between 35 and 54 years old. Drivers 18 to 24 years old complained the most about glare from vehicles behind them.
Density, color and position make a difference
Lights have gotten smaller over time, and “any given intensity appears brighter if it’s emitted by a smaller apparent surface versus a larger one,” said Daniel Stern, chief editor of Driving Vision News, a technical journal that covers the automotive lighting industry.
“Tall pickups and SUVs and short, small cars are simultaneously popular,” he added. “The eyes in the low car are going to get zapped hard by the lamps mounted up high on the SUV or truck every time.” (Almost half of the 280 million registered passenger vehicles in the United States are SUVs or pickup trucks.)
LED and high-intensity discharge headlights can appear more blue in their output spectrum than halogens, and they often provoke “significantly stronger discomfort reactions” than warm white or yellowish lights, Stern said.
“Blue light is difficult for the human visual system to process because blue wavelengths tend to focus just ahead of the retina rather than on it,” he said.
“Brightness” is not a term generally recognized by scientists and researchers, who refer instead to lumens, or the output of a light. Halogen lights put out 1,000 to 1,500 lumens, while high-intensity discharge lights and LEDs can measure 3,000 to 4,000 lumens.
“It’s the concentration we need to pay attention to,” said M. Nisa Khan, president of IEM LED Lighting Technologies, a research and engineering company based in Red Bank, New Jersey.
“What falls on your eyeball is what matters,” she said. “The lumen density, when it really aggregates and goes through the roof, that’s when our eyes will start to complain.”
Stern said other major contributors to the problem include headlight aim, which gets scant attention but is “far more important than the technology in the headlamp or how much light it puts out,” and the widespread availability of aftermarket LED bulbs and high-intensity discharge kits.
What are some solutions?
David Aylor, manager of active safety testing at the Insurance Institute for Highway Safety, said technology known as high-beam assist automatically switches high beams to low beams when it senses an oncoming car.
The feature, which was introduced about five years ago, is becoming more readily available.
Whether it has reduced complaints about headlight glare is not yet clear, Aylor said.
Adaptive driving beam, another technology, is widely used in Europe but is not yet legal in North America.
Kossoff of The Retrofit Source described it as “very James Bond-like” and “very cool.” It relies on sensors that can detect oncoming traffic and adjust the projected beam pattern to allow plenty of light for the driver without blinding other motorists.
The National Highway Traffic Safety Administration said it was working to finalize rules allowing the use of adaptive driving beam technology in the United States, though it was unclear how long that might take.