Blinded by Efficiency
The Hidden Costs of a Brighter Night
We have spent years making artificial light cheaper, brighter and more energy efficient. LEDs have delivered substantial electricity savings, longer operating lives and greater control over illumination.
But the consequences of a brighter night extend beyond electricity bills.
Consider headlight glare. An October 2026 RAC survey found that 83% of surveyed UK drivers were concerned about it as darkness fell. Half of those who said they had been dazzled reported that bright headlights made hazards harder to spot.
The evidence does not establish that LEDs are responsible. Headlamp aim, mounting height, vehicle orientation and road geometry can all influence glare. A small simulated-driving test comparing LED colour temperatures also found no significant effect on reaction time or discomfort-glare ratings, though its results are limited to the test conditions.
The concerns extend beyond driving.
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A 2026 systematic review found an association between greater artificial light exposure at night and sleep disturbance, although most included studies had a high risk of bias.
Wildlife presents another dimension. Research has associated artificial light at night with reduced melatonin secretion and changes in bird physiology and behaviour.
A Swiss forest experiment offers a particularly striking example. Dark plots recorded 91% fewer captures of flying insects and ground-dwelling arthropods than illuminated plots. Reducing lighting intensity by 50% cut captures by 22%. These results concern trap captures, not regional population estimates.
The common thread is not that LEDs are inherently harmful. It is that artificial light has consequences beyond the task it was installed to perform.
LEDs remain an important energy-saving technology. But producing light efficiently does not justify using it everywhere.
A 2026 review in Nature Reviews Biodiversity proposes three steps: remove unnecessary lighting, control where and when the remaining light is used, and then optimise its spectral composition.
We have made artificial light easy to produce. Perhaps it is time to recognise that darkness has value, too.
Read the full analysis:
https://structuralsignals.com/blinded-by-efficiency/
Should preserving natural darkness become a formal consideration in urban planning, alongside energy efficiency and public safety?
