One in 10 drivers said they were typically unable to see clearly for six seconds or more when faced with oncoming SUV headlights, according to a UK study, reports The Telegraph.

Things may even be worse here in America. While it has been the subject of little research, high-mounted headlights glaring straight into the eyes of other road users has become a safety concern on U.S. roads — where SUVs are very prevalent. .

For example, Streetsblog USA points to a 1993 study. It found that 12-15% of car crash deaths were "caused by glare from the high-beam headlights of oncoming traffic at night." The article notes: That was back when the bestselling Ford F150 sat five inches shorter than it does today.

Simply stated, people driving low cars — which are also very popular in the U.S. — have their eyes subjected directly to the blinding lamps mounted up high on the SUVs or pickup trucks.

Addressing Glare

Improving headlight performance has been a major focus for the Insurance Institute for Highway Safety (IIHS) in recent years, and addressing headlight glare is a big part of that.

“To do well in those tests, a vehicle needs to put light down the road effectively without exceeding glare thresholds. Some automakers have gotten the message quickly, while others have taken some time,” said Joseph Young, director of media relations, Insurance Institute for Highway Safety. “Some vehicle types, like SUVs and pickups, have struggled to find the right balance because they tend to sit higher.”

Even so, noted Young, manufacturers are consistently making improvement in terms of both visibility and glare, and more and more vehicles are earning the IIHS’ highest headlight rating of “good” each year.

Headlight aim is another concern. Aim is an important part of performance, and improper aim is often responsible for glare. Many vehicles have transitioned to LED headlights in recent years, which are brighter and have the potential to produce excessive glare if aimed incorrectly, so these can be particularly concerning. That said, the glare problem is getting better.

“When we launched the program in 2017, about one in five headlight systems tested produced excessive glare,” said Young. “We’ve seen improvements, and in 2023 only 5% of tested vehicles cause excessive glare. In some cases, vehicles have shifted a poor rating to a good rating solely by re-aiming headlights and reducing glare.”

Moreover, Young noted that the average age of a vehicle on U.S. roads is about 12 years. So like any safety challenge, it’s going to take time for improvements to be widespread. The IIHS expects to see real-world glare improve as older vehicles are replaced with newer ones.

Better Headlights Reduce Crashes

The bottom line is that better headlights — including those that cause less glare — are proving effective at preventing crashes. A recent study of vehicles that have been rated in IIHS evaluations found that good-rated headlights have nighttime crash rates about 19% lower than those with poor-rated headlights.

Moreover, an IIHS data evaluation of headlights from 2015 to 2020 found that compared with poor ones, good-rated headlights reduced the rate of crashes in which the driver was injured by 29% and the rates of tow-away crashes and pedestrian crashes by about a quarter each.

Why does headlight performance make such a difference in safety? The IIHS explains it this way: It takes 1.5 seconds for a driver to react to an unexpected event under ideal conditions. At a speed of 55 mph, a car travels about 120 feet during this brief period. Once the driver applies the brakes, it takes more than 144 feet, on average, to stop at this speed

The low beams of many headlight systems with poor ratings don't provide enough light for a driver going 55 mph on a straight road to stop in time after spotting an obstacle in his or her lane. They provide even less illumination on the left side of a straight road and when driving on a curve.

However, glare — like that coming from many of today’s SUV headlights — is an equally troubling problem. Properly aimed headlights can illuminate the road ahead without getting in other drivers' eyes. It's also possible to have headlights that provide poor visibility and also cause excessive glare.

As automakers continue to tackle the problem of excessive glare from headlights on taller vehicles like SUVs and pickups, drivers need to remain vigilant, That means sticking to the speed limits, slowing down especially on curvy roads, and staying focused on the road — particularly at night when blinding headlights can suddenly appear at any time.