It’s time for a wake-up call for car manufacturers, consumers, and policymakers alike: while those bright, blue-shifted “cool” white headlights might look sleek and modern, they are actually having a serious negative impact on moth populations and other nocturnal wildlife.
The good news? A simple solution: switching to warmer-toned LEDs, like amber or yellow, would drastically reduce the harm to moths without compromising safety for humans. In fact, there’s no proven safety benefit for humans from the blue light specifically used in car headlights.
This has been found by researchers from the University of Exeter who have shown that these bright, blue-toned lights disorient moths, causing them to fly erratically or even directly toward the light, a behavior that makes them more vulnerable to collisions with vehicles and predators like bats.
These disruptions aren’t just a nuisance—they can interfere with the moths’ ability to feed, mate, and pollinate, which is crucial for many ecosystems.
“Moths exposed to this light were 80% more likely to fly erratically or towards the light, compared to those exposed to other lights – and 25 times more likely to fly in these abnormal ways compared to a control group not exposed to any light,” said the study.
Moths, as pollinators and prey, play a significant role in maintaining biodiversity. The good news is that a simple change—switching to warmer, amber-toned headlights—could reduce these negative effects on moths and other nocturnal creatures.
Light pollution is implicated in their declines and most studies have focused on the effect of streetlights. However, vehicle headlights create intense pulses of light along road networks that extend deep into rural and “dark sky” areas.
“Vehicle headlights are becoming ever brighter and bluer,” said Dr Jolyon Troscianko, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.
“In humans, our pupils can change size in less than a second in response to dazzling glare, but in insects the process can take tens of minutes, potentially making them highly vulnerable.
“Moths that fly towards car headlights may be killed in a collision, while erratic flight also wastes energy and may increase the risk from predators such as bats.
“Many moths are only active for a very short time at night, so this disruption could interfere with their ability to feed and find mates.”
The research team caught and released 428 moths from 64 species on the Penryn Campus, exposing each moth for 10 seconds immediately before release to “Cool” (blue-shifted) white phosphor-coated LEDs, “Warm” (amber-shifted) white phosphor-coated LEDs, “Cool” RGB (Red-Green-Blue) LEDs – light from three LEDs of different colours, “Warm” RGB LEDs and no light (control group).
On release, moths from the light-free control group typically flew either up or down. Those exposed to the cool phosphor-coated LEDs were more likely to fly towards the light, or in tight circles (something rarely seen in moths when night-lighting is not present).
“Simply by switching to warmer-coloured LEDs or different LED technology, we can dramatically reduce their impact on moths,” said Madeleine Fabusova, who collected the data as part of her MSci in Conservation Biology and Ecology at the University of Exeter.
“The phosphor-coated cool LEDs were more harmful than RGB LEDs that have an identical white colour to human vision.
“Our results were remarkably consistent across different moth species.
“Reducing the blue spectrum in headlights may therefore benefit moths, the flowers they pollinate, and the animals that feed on them.”
Commenting on the trend for brighter, bluer headlights, Professor Kevin Gaston, of the Environment and Sustainability Institute at the University of Exeter, said: “There’s no safety benefit to humans from these blue lights compared to lights with more red and green – the current trends appear to come from car manufacturers.
“Car manufacturers, consumers and policymakers could all play a role in making a fairly simple change to reduce our impact on the natural world.”
The study published in the journal Biology Letters, is entitled: “Pulsed artificial light at night alters moth flight behaviour,” was funded by the Natural Environment Research Council.
It’s a small adjustment that could make a big difference for wildlife, without compromising human safety, since there’s no proven safety benefit to the blue light from a driving perspective.
So, in a way, making headlights “cooler” for moths—by dialing down the blue spectrum—would be a win for both nature and our roads. That is, we can protect these vital pollinators and help preserve the delicate balance of our ecosystems.
