If you think headlights are getting too bright, you’re not alone.
A recent survey found that 97 per cent of U.K. drivers report being “dazzled” by headlights at least some of the time – and a third said they had either stopped driving or were driving less at night because of glare from headlights.
While the U.K. government has vowed to review its headlight rules, it is already tougher on glare than the U.S. and Canada.
“We really don’t care about glare in North America – we never have,” said Daniel Stern, a Vancouver-based automotive lighting consultant and senior editor of Driving Vision News. “The U.S. [regulatory] philosophy has been – for as long as there have been electric headlights – that a low beam should provide as much seeing light as possible for the driver while controlling glare to other traffic, if possible.”
Most of the world takes the opposite approach, focusing on keeping light out of other drivers’ eyes – even if that means less light on the road, Stern said.
It gets complicated, but, generally, Canadian and U.S. rules allow more light to shine toward oncoming drivers than other countries do.
“Canada permits both headlight systems [but the U.S. doesn’t],” he said. “In practice, almost all vehicles sold in Canada have the U.S. headlights just because of the integration of the [U.S. and Canadian] markets.”
Blinded by your lights: In a battle to see, why are blinding headlights winning?
Transport Canada in the dark
So how do Canadians feel about glare? Transport Canada told us it doesn’t track the total number of complaints it gets about headlight glare – but it is planning a nationwide survey next year.
Stern, who has worked as a consultant for Transport Canada, said the agency told him it gets a substantial number of complaints.
“Drivers in Canada do feel endangered by traffic glare,” he said. “The content of those complaints is virtually identical to the ones referred to in that U.K. study.”
Research into glare divides it into two types: discomfort glare, which is annoying or even painful, and disability glare, which makes it harder to see, Stern said.
The U.K. study looked at discomfort glare – how bright headlights feel – not whether they were actually impairing drivers’ vision.
“It is really tempting to say, ‘I know what I can see,’ but the human visual system is a terrible judge of its own performance,” Stern said. ”Whether that means judging how well we can see or judging how glaring a light source is.”
While there’s evidence that disability glare can cause crashes, it’s not clear whether discomfort glare does too.
“It is extremely difficult to prove a link between discomfort glare and traffic safety,” Stern said.
A study released last month by the Insurance Institute for Highway Safety looked at crashes where glare was mentioned as a contributing factor in police reports in 11 states.
Between 2015 and 2024, glare was only reported as a cause in less than 0.2 per cent of nighttime crashes – and that number stayed flat over the years, even as automakers made headlights better at illuminating the road. Those crashes “disproportionately” involved older drivers and older vehicles swerving into another lane on lower-speed roads, according to the study.
Even if oncoming headlights aren’t literally blinding, are they distracting?
“I think distracting is a very fair word,” Stern said, adding that, unlike texting and driving, it’s an involuntary distraction. “It seems kind of sadistic [for governments] to say we’re going to punish you if you choose to be distracted, but if you’re distracted involuntarily … well, you’re just going to have to live with it.”
How LED lights fit in
So why are complaints rising even in countries with strict glare controls that we don’t have here – including regular headlight aim inspections?
Part of the answer is that carmakers everywhere have been switching to LED lights, which can look harsher to oncoming drivers than older technologies such as halogen, Stern said.
The problem isn’t the LED technology itself, but that carmakers are using it to make headlights smaller and bluer, he said.
“The light-emitting area of many current LED headlamps is about the size of a credit card or smaller,” he said. “And that drives up luminance, which is what creates that piercing, almost laser-like sensation people complain about.”
So, even when a small headlight is emitting the same amount of light as a bigger headlight, it still looks brighter to oncoming drivers, Stern said.
And most LED headlights emit a cool blue-white light, which looks brighter and harsher to our eyes than warmer yellow-white light, even at the same measured intensity of light.
Automakers choose blue-white headlights because consumers think they make it easier to see the road – but that advantage is “an illusion,” he said.
“There is no seeing advantage [with bluer light],” he said. “You get zero per cent better seeing, but 60 per cent more discomfort glare.”
Switching to warmer-toned LEDs could reduce the level of discomfort glare experienced by oncoming drivers, Stern said.
“We could keep intensity the same and reduce glare by going to a warmer white,” he said. “Or, we could keep glare the same and greatly improve seeing [by going to a warmer white and increasing the intensity].”
Looking ahead?
Stern worries that governments could respond to public frustration by deciding to make headlights dimmer.
“If they pursue this path of letting subjective perceptions drive their regulations, I don’t think it’s hyperbolic to say they will wind up killing people,” he said.
Instead, we need more research into discomfort glare and whether it’s distracting enough to cause crashes, he said. Transport Canada said it conducted glare tests on a track earlier this year, but the results haven’t been published.
There are some tools to potentially reduce glare – including requiring warmer-toned LEDs and setting a minimum size for headlights – that won’t necessarily make it harder for drivers to see, but there’s no way to eliminate glare entirely, Stern said.
“There will always be some level of headlight glare,” he said. “Because the simple fact is that other drivers’ eyes coincide with areas of the road that need to be lit so we don’t hit things or people.”