LED lights could be ‘the new asbestos’, UCL scientists warn

Scientists fear prolonged exposure to LED lighting could raise the risk of diabetes and other metabolic disorders by disrupting the way cells generate energy, with one UCL expert describing the technology as a “clear and present public health emergency” comparable to asbestos

LED lighting in homes, schools, offices and hospitals could increase the risk of diabetes and other metabolic disorders, experts from University College London have warned.

Speaking to The European’s Steve McCauley, Professor Glen Jeffery and Dr Bob Fosbury fear prolonged exposure to LEDs may interfere with the way cells generate energy and say people should spend time outdoors in natural daylight every day to help counter the effects.

The bulbs produce relatively high levels of short-wavelength blue light while containing little or no near-infrared light, which the researchers believe plays an important role in keeping cells functioning properly.

Conventional incandescent and halogen bulbs emit a much broader spectrum, including red and near-infrared wavelengths that are also found naturally in sunlight.

Red and near-infrared light helps mitochondria – the structures inside cells that generate energy – function efficiently, while excessive exposure to short-wavelength blue light may impair them and contribute to disease.

Jeffery and Fosbury fear people who spend much of their lives indoors under LED lighting could experience a chronic form of light deficiency with potentially serious consequences for their health over many years.

They recommend spending time outside in natural daylight every day and using at least one conventional incandescent or halogen bulb in each room to restore some of the wavelengths missing from LED lighting.

Jeffery, Professor of Neuroscience at UCL’s Institute of Ophthalmology, says that the body can begin responding to exclusive LED lighting within minutes, but the concern about more serious health effects relates to repeated or prolonged exposure over time.

He says that the issue is less about the number of LED bulbs in a room than how much of the day someone spends under them with little exposure to natural daylight or longer wavelengths – such as an office worker in winter who commutes in darkness and spends most of the day indoors.

Jeffery believes the potential implications are serious enough to compare the issue with asbestos, which was widely used before its health risks became understood.

Jeffery said: “LED lighting is damaging mitochondria and therefore there is no question it is also damaging systemic health.

“Exclusive LED lighting is detrimental in a matter of minutes. Your body will certainly respond within a few minutes and this becomes damaging.

“The more serious health problems come with longer exposure, but people increasingly spend much of their time in environments deprived of natural sunlight and are therefore getting that exposure all the time.

“This is a clear and present public health emergency, comparable to asbestos, and we need to take action.

“This area of research is slowly shaking out, but I feel confident enough to stick my neck out and say that it is bad, bad news.”

The warning follows years of government efforts to replace traditional bulbs with LEDs because they consume substantially less electricity and last longer.

Most halogen bulbs for general household use were withdrawn from sale in Britain in 2021, by which point around two-thirds of bulbs sold were already LEDs. The Government previously estimated LEDs could use up to 80 per cent less electricity than halogen alternatives and help cut carbon emissions by 1.26 million tonnes a year.

Jeffery and Fosbury argue that the drive for energy efficiency may have overlooked the biological role of wavelengths that contribute little to visible illumination.

Sunlight contains a broad spectrum of wavelengths, including red and near-infrared light, while incandescent and halogen bulbs also emitted substantial amounts of longer-wavelength radiation, much of it as heat.

The pair’s concerns are backed by a human study by Jeffery and fellow UCL researcher Edward Barrett published in Scientific Reports in January, which tested whether supplementing an LED-lit environment with broader-spectrum light could produce measurable effects in humans.

Twenty-two healthy adults aged between 23 and 65 took part, with half exposed to tungsten lighting containing longer wavelengths including infrared and the other half remaining under normal LED lighting.

After two weeks, those exposed to the broader-spectrum light showed significant improvements in colour-contrast vision, with the effect persisting for two months.

Although the study measured visual performance rather than disease or broader systemic health, Jeffery and Fosbury’s theory is supported by separate experiments involving fruit flies that found daily exposure to short-wavelength blue light reduced measures of mitochondrial activity by around 50 per cent.

Research in mice, meanwhile, found animals exposed to ordinary LED lighting became less active, gained weight and developed fatty liver disease.

The wider claim that LED lighting can cause diabetes or other systemic disease in humans remains a hypothesis, with long-term studies yet to establish such a link.

But Fosbury, an astronomer emeritus at the European Southern Observatory and honorary professor at UCL’s Institute of Ophthalmology, said: “It was not until a decade after the introduction of the LEDs that we really became aware of the problem.

“Life on earth is an antenna tuned to sunlight. Life has evolved to utilise the sunlight that gets through the atmosphere to its maximum extent.

“We call it photometabolism. The human body needs components of sunlight to metabolise properly. This goes back over four billion years of evolution.”

Fosbury, who previously worked for 26 years at the European Space Agency (ESA), compares the potential problem with scurvy and describes modern indoor environments as “infrared darkness”.

“The absence of infrared light in the artificial lighting environment decreases the efficiency of your mitochondria,” he said.

“You’re less able to metabolise properly, over a timescale of days, weeks, months.

“This is what’s happening to the urban population today, all living indoors. They are living in a state of infrared darkness.”

The researchers are now exploring ways to restore the wavelengths missing from modern indoor lighting, with Jeffery’s laboratory experimenting with adding near-infrared light at around 850 nanometres to LED systems.

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