How switching your old lightbulbs for new LED lights increases your risk of diabetes, obesity and even dementia – as experts reveal disturbing link between modern lamps and disease

It sounds almost too good to be true, but researchers think that shining red light at patients could be a powerful and drug-free way to treat everything from sight loss and type 2 diabetes to paralysis and even dementia.

This type of light, just one part of the light spectrum that our eyes see all the time, is gaining a reputation among some scientists as a simple, safe therapy for illnesses that affect millions.

The NHS spending watchdog (National Institute for Health and Care Excellence) already recommends it for the treatment of oral mucositis, a painful and distressing side-effect of the chemotherapy and radiotherapy used to treat head and neck cancer.

Just 20 to 30 minutes of exposure to red light from a toothbrush-sized probe, two to five times a week, has been shown to dampen inflammation (and therefore pain) in the gums triggered by cancer treatment.

And in January this year the US Food and Drug Administration authorised the use of red light in the treatment of dry AMD (age-related macular degeneration), the leading cause of sight loss in the UK. There is currently no treatment for the condition, which causes steadily deteriorating eyesight.

In dry AMD the light-sensitive cells of the retina progressively die. These cells are essential for central vision and seeing details.

As part of a trial, reported last year in the journal Retina, patients were given six series of treatments with red light – five minutes in each eye, delivered every four months. After 13 months, around 55 per cent of treated eyes experienced a notable increase in vision by at least five letters on a standard optician’s chart. A larger study is under way to see if these results can be confirmed.

But while red light is proving beneficial in tackling some hard-to-treat conditions, are other forms of light to blame for ill health?

A number of experts fear exposure to light from screens and LED lamps (the modern type of bulb we use in our homes) is fuelling a rise in obesity, anxiety, blindness and certain cancers.

That’s because they emit mainly blue light, a high-energy form of light which, in excess, can disrupt our body clocks, damage the retina and play havoc with the release of melatonin, the hormone we rely on to regulate sleep.

(In contrast, the old-style incandescent electric lightbulbs – which were banned in the UK in 2016 to reduce energy use – provide the same spectrum of light as sunshine.)

Research published this year in Scientific Reports found that mice exposed to high levels of blue light rapidly gained weight and showed significantly raised levels of anxiety.

And a 2020 study of 2,000 people by the Barcelona Institute for Global Health, published in Epidemiology, found those with the highest exposures to nocturnal blue light had a 60 per cent higher risk of bowel cancer – thought to be a result of sleep disruption.

But what is it that makes red light good, and blue light bad?

The answer, some experts believe, is the way they affect the mitochondria, the tiny ‘battery packs’ inside every cell that generate the energy needed to survive.

‘Red light boosts our mitochondria energy, blue light depletes it and harms our cells’ function,’ says Glen Jeffery, a professor of neuroscience at the University College London Institute of Ophthalmology, who has conducted several clinical trials exploring the curative potential of red light.

‘Modern lighting is undermining public health. LED lights have almost no red light and a lot of blue. Mitochondria don’t like it.’

He says, for example, that animal studies show a much better recovery rate from stroke with exposure to red rather than blue light, due to the effects on mitochondria in brain cells.

He told Good Heath: ‘Red light boosts the energy inside our mitochondria, which provide the energy inside all human cells, enabling them to function.

‘Mitochondria are effectively batteries with a charge – and red light increases that charge.’ This happens because chemicals inside mitochondria become energised by power from the specific energy-carrying photons (a type of particle) in red light.

In turn, the mitochondria increase the energy that they produce inside our cells.

As we age, mitochondria energy wanes. In diseases such as dry AMD, problems can be driven by falls in energy production by mitochondria in the retina cells, so they stop working properly.

Research by Professor Jeffery suggests staring at a deep red light for three minutes a day can significantly improve declining eyesight that comes with age.

His 2020 study, in the Journal of Gerontology, asked 24 healthy volunteers to shine a red light torch – with a specific wavelength of 670nm – into their eyes for three minutes a day for two weeks. Their eyes were closed, because eyelids don’t block red light.

In those aged over 40, the ability to see in low light improved significantly and their ability to detect colours improved by up to 20 per cent.

Professor Jeffery says: ‘These red light exposures can recharge the energy system that has declined in the retina cells, rather like recharging a battery. The technology is simple and safe. Our devices cost us only about £12 to make.’

(Such lights are available online, though there is no guarantee they are safe or correct, so it is a case of buyer beware.) More recently, Professor Jeffery found red light therapy might combat damaging sugar spikes in people with type 2 diabetes.

His study, reported in the Journal of Biophotonics last year, involved exposing the skin on the backs of 15 patients to red light for 15 minutes, before giving them a sugary drink and testing blood sugar levels over two hours. The results showed spikes were lower – as were total sugar levels – compared to those given the drink but not exposed to red light.

‘Our mitochondria need blood sugar in order to get the energy to charge their batteries,’ says Professor Jeffery.

‘If we make the mitochondria work harder [by exposing them to red light] they take more blood sugars, which stops the sort of spikes in the bloodstream that can lead to type 2 diabetes.’

Meanwhile, scientists at the Technical University of Denmark are deploying a different light to tackle dementia. The technique involves beaming a flickering light through the eyes to induce beneficial gamma waves in patients’ brains.

Previous studies found this can reduce the brain’s production of toxic amyloid plaques associated with the disease. Furthermore, gamma brainwaves invigorate cells in the brain responsible for destroying the plaques.

Early clinical trial results suggest patients with mild to moderate Alzheimer’s who were exposed to the lights for 30 minutes daily for three months experienced improved speech and memory abilities.

The Alzheimer’s Society says the technique is ‘promising’ but warned it’s too soon to recommend light therapy.

At the University of Birmingham, red-light therapy is being pioneered as an emergency treatment for people with potentially paralysing spinal injuries.

Lab tests show it stimulates mitochondrial energy in damaged nerve cells, enabling them to regrow and significantly restore sensation and movement.

One of the device’s developers, Zubair Ahmed, a professor of neuroscience at the University of Birmingham, told Good Health that a red light device could be implanted rapidly into the backs of spinal injury victims.

‘In spinal trauma the physical damage causes an energy crisis in the nerve cells. This sets off lots of degeneration in the nerves, which can lead to paralysis. Red light therapy balances that.’

But not everyone is convinced that red light is really a panacea for so many ills.

Russell Foster, a professor of circadian neuroscience at the University of Oxford, told Good Health: ‘These studies have major flaws, and too many assumptions are being made.

‘Extrapolation from lab mice to humans is deeply problematic as the light sensitivities between mice and humans differ hugely.’

Is there a simpler way to get the red light we need? ‘My red light therapies don’t provide anything you can’t get from sunlight,’ says Professor Jeffery. ‘We need about one hour’s sunlight exposure per day to be healthy – the equivalent of a good walk in the park.

‘Plant matter strongly reflects infrared to protect it from overheating. This means that green spaces are full of this light being bounced around. So it is much better to be in natural environments than in concrete jungles.’