I have subscribed to New Scientist for several decades and trust it as a highly reputable source of scientific news and information.

I was therefore very interested to see that the print edition published on 15 August 2026 featured a stark image of a light-emitting diode (LED) bulb with the disquieting headline:

Why this bulb is wrecking your health

The lead article explained that the worldwide drive to make our buildings more energy efficient by replacing incandescent bulbs with LEDs may have come at a cost nobody anticipated.

And some scientists are very concerned about it. Dr Glen Jeffery, Professor of Neuroscience at University College London, goes so far as to say, “This is an issue on the same level as asbestos.”

The problem with LEDs

For most of the twentieth century, we lit our homes with incandescent bulbs. They weren’t particularly energy efficient, but the light they produced had a broad, continuous spectrum containing plenty of red and infrared wavelengths.

Then along came the drive to save energy.

Incandescent bulbs were labelled inefficient, governments around the world began phasing them out, and we were encouraged to switch to more energy-efficient alternatives. LEDs eventually became the most popular choice because they use much less electricity and last longer.

But there was a problem that had not been thoroughly investigated: What happens to human health when you radically change the spectrum of light people are exposed to for hours every day?

Most people followed their governments’ advice, but Richard and I didn’t make the switch in our home. We could feel that LED lighting didn’t have the same etherically nurturing quality as incandescent light, so we bought as many halogen bulbs as we could while they were still available. Their light is much closer to incandescent light, and we still use them today.

What’s missing from LED light?

For virtually all of human history, our main source of light has been the sun, and after sunset, we used firelight and later candles. All these forms of light contain plenty of longer red and infrared wavelengths.

Incandescent and halogen bulbs also produce substantial quantities of these longer wavelengths.

But LEDs don’t.

This difference may matter far more than anyone realized when incandescent bulbs were phased out.

Warm-white LEDs contain visible red light but usually emit little or no infrared. They typically have a pronounced blue peak around 450 nm. Some LEDs also produce substantial flicker, which may not be consciously detectable but can cause eyestrain, headaches, migraines, and other effects in some people.

Light doesn’t just illuminate our surroundings, though. Longer wavelengths of light can penetrate biological tissues and influence cellular processes, which is why there is growing concern about the restricted spectrum of LED lighting.

This is where mitochondria enter the story.

Why mitochondria matter

You may remember mitochondria from school biology lessons, or perhaps you’ve never even heard of them.

But you couldn’t live without them.

Mitochondria are tiny structures inside nearly every cell in your body. One of their most important jobs is to convert energy from food and oxygen into adenosine triphosphate (ATP) — the usable form of energy that powers your cells.

And you need an astonishing amount of ATP.

An adult human generally recycles an amount equivalent to their own body weight in ATP every 24 hours.

ATP is powering your heartbeat as you read this. It’s powering your breathing, your brain as it makes sense of these words, your muscles as you move, your digestion, your immune system, and the constant repair and renewal taking place throughout your body.

In other words, if your mitochondria aren’t working properly, your health is likely to suffer.

What does all this have to do with light?

Scientists have discovered that mitochondria respond to light.

Long-wavelength red and near-infrared light, particularly in the 650–900 nm range, can stimulate mitochondrial activity and increase ATP production. Blue light can have very different effects, with some experimental studies finding impaired mitochondrial function.

What this means is that for most of human history, we spent our days exposed to sunlight containing abundant red and infrared wavelengths. Today, many people spend most of their waking hours indoors under LED lighting that contains little or no infrared.

This has led some researchers, including Jeffery, to investigate whether the widespread loss of long-wavelength light from our indoor environments is affecting human metabolism. In particular, they are investigating whether this may contribute to diabetes, dementia, cancer, cardiovascular disease, obesity, and other conditions.

Why red-light therapy is not the answer

Even before this new research about the effects of LED lighting was published, increasing numbers of people started experimenting with red-light therapy, with the aim of improving skin health, assisting wound healing, reducing signs of aging, boosting vitality, and so on. One proposed mechanism is that red and near-infrared light stimulates mitochondrial activity and ATP production, which can support cellular repair.

This raises two obvious questions:

Would this treatment even be needed if people weren’t spending their days bathed in blue-rich artificial light that contains little or no infrared?

Wouldn’t it be better to treat the cause of the problem instead of trying to artificially replace what’s missing?

The crux of the issue is that in our modern world, many people spend up to 90% of their time indoors, exposed to LED lights and glued to blue-light-emitting screens. Trying to compensate for the lack of long-wavelength light with red-light therapy is like spending all day in a stuffy room and then taking an oxygen treatment instead of opening the windows. Surely it makes more sense to change the environment we live in.

What can you do?

The purpose of this article is to make people aware of the problem. Scientists and lighting manufacturers will need to find solutions, which may include re-engineering LEDs, creating more energy-efficient halogen bulbs, changing the properties of window glass so that more beneficial long-wavelength light can enter our buildings, and changing the way screens are lit.

But we don’t need to wait for all that before doing something ourselves. There are some simple changes you can make right now.

• Let “daylight before dopamine” be your mantra for how you start your day. Before you check your phone or use another internet-connected device, aim to spend at least 20 minutes outside in natural daylight each morning, preferably before 11 am. Research suggests that mitochondria are markedly more responsive to long-wavelength light earlier in the day.
• In the areas of your home where you spend the most time, replace LED bulbs with halogen lights, if you can. They are still available in many countries, if you search for them.
• In the areas of your home where it’s not possible to replace LED lights, use them as little as possible.

Copyright © Clear Space Living Ltd 2026

Resource
If you have poor-quality sleep or difficulty sleeping, my Change Your Bedroom online course includes a range of tried-and-tested remedies, including changes to bedroom lighting, Wi-Fi exposure, and more.

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