In an era where we spend up to 90% of our lives indoors under artificial lights, a silent public health emergency is unfolding.

Professor Glen Jeffery, a leading academic at University College London, warns that our reliance on LED lighting is starving our bodies of essential infrared light, leading to mitochondrial dysfunction, slowed metabolism, and a cascade of age-related diseases. This isn't a distant threat; it's happening now, exacerbating conditions like diabetes, vision loss, and frailty in our ageing populations.

The science is clear, and the solutions are astonishingly cheap and straightforward, but inaction could turn this into a ticking time bomb for global health systems.

Mitochondria, the powerhouses of our cells, are at the heart of this crisis. As Jeffery explains, these organelles "regulate our metabolism and regulate loads of other things, regulate the pace of our aging." They require glucose and oxygen to produce ATP, the energy currency of life. However, modern LED lights disrupt this process. "That lighting really undermines mitochondria. They really don't like it and the consequence is there's a slowing of metabolism," Jeffery states. 

In a recent study, his team replaced LEDs with old-fashioned incandescent bulbs in a windowless workspace at University College London. The results were striking: "Everyone's vision improved and it improved significantly."

This isn't just about eyesight. Jeffery's research shows systemic effects. In one experiment, exposure to deep red light mimicking the infrared component of sunlight lowered blood glucose levels by stimulating mitochondria to consume more glucose and oxygen. "The red light stimulates the mitochondria... which grabs the glucose out of your serum and consequently your blood glucose levels go down. Likewise your oxygen consumption goes up," he notes. 

Another study revealed that sunlight's infrared wavelengths penetrate straight through the body, are detectable on the opposite side of the chest, and improve visual function the next day. These findings extend to motor skills: researchers at Westminster University found that adding infrared to LEDs boosts grip strength, a key marker of overall health and ageing.

The urgency stems from our evolutionary mismatch with modern environments. Humans aren't designed for prolonged indoor life under blue-heavy LEDs, which block the infrared light our bodies crave. Jeffery draws a powerful analogy: "Our current situation is analogous to scurvy." Just as sailors suffered and died from vitamin C deficiency on long voyages, we're now in "infrared starvation" due to infrared-blocking windows and artificial lights. "We as a population have evolved such that we're going into a strange environment. We sit in buildings for vast amounts of time with infrared blocking glass on our windows and we get sick," he warns.

Population data underscores the peril. "All cause mortality is higher in those individuals that spend less time in the sunlight than those that spend a lot of time in sunlight," Jeffery emphasises. In the Northern Hemisphere, deaths peak just after Christmas; in the Southern Hemisphere, at the end of June, perfectly aligned with reduced sunlight exposure. Blood sugar control is markedly better in sun-exposed populations, based on studies involving tens of thousands across Europe. Even skin cancer statistics flip expectations: those affected often have low vitamin D levels despite sun exposure, suggesting we've misunderstood sunlight's role. 

"We've really got it wrong." says Jeffery.

Diseases like Parkinson's and macular degeneration, primarily mitochondrial, are rising, alongside diabetes epidemics worsened by poor blood sugar control. The ageing global population is exacerbating the crisis. The decline in mitochondrial function with age significantly reduces ATP production, by as much as 70%. As Jeffery explains, "As you age, your mitochondria just start to pack up... the whole system is starting to become frail and then it only takes a small knock and the pack of cards goes over."

Yet, the fixes are straightforward and low-cost. Incandescent bulbs, now harder to find due to energy policies, emit beneficial infrared. In one accidental experiment, a single infrared-emitting bulb in an LED-lit office improved vision for everyone. "You don't need much infrared light to improve the situation," Jeffery says. Nature offers even better: "Go grab a leaf in strong sunlight... the reflection of the infrared light is very close... to a therapeutic dose." 

A 20-30 minute walk in a park floods the body with reflected infrared from plants, which "shout" it back at us invisibly.

Exercise compounds the benefits, as mitochondria thrive on both.

Clinical environments demand immediate change. Patients near windows recover faster, yet many wards use harmful LEDs. Jeffery is engaging with bodies like NICE (National Institute for Health and Care Excellence) on the subject of light. 

"We've got traction," he says, but commercial hype around unproven red light devices muddies the waters. 

His advice: Avoid gimmicks. Instead, prioritise sunlight and rethink built environments.

This is a public health imperative, not a fringe theory. "It's a time bomb and it's ticking," Jeffery declares. Governments pursue net zero with LEDs, overlooking the unforeseen health costs. Architects and lighting engineers are listening faster than medics, incorporating "well-being" through daylight. 

But we can't wait for policy shifts. Start today: Swap an LED for an incandescent bulb (available for ovens), step outside, and demand better lighting in offices, homes, and hospitals. Our mitochondria and our future are at stake. If we ignore this now, the burden of frail, diseased populations will be catastrophic.

Light is literally the key to healthier, longer lives; let's not let it fade.