Is a ‘light deficiency’ quietly ageing you faster? – with Professor Glen Jeffery

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Wellbeing Team

12 March, 2026
Is a ‘light deficiency’ quietly ageing you faster? – with Professor Glen Jeffery

One of the most powerful tools for healthy ageing might be something you’ve barely thought about: light. Most of us spend the majority of our time under LED lighting that’s stripped of the very wavelengths our bodies need to function well – and the impact on our metabolism, energy and long-term health is only just being understood.

Professor Glen Jeffery, neuroscientist at UCL’s Institute of Ophthalmology, joins Liz to explain why a light deficiency could be quietly accelerating ageing, what it means for your mitochondria, and the simple changes – starting with your light bulbs – that could make a real difference to how you feel and age.

Stream the episode below, or download the recording via Apple Podcasts or Spotify.

5 ways light deficiency could be ageing you faster

Here are five surprising ways a lack of natural light could be influencing how we age.

Your cells depend on light for energy

At the heart of Jeffery’s research is the role of mitochondria. These are the tiny structures in our cells responsible for producing energy.

“Mitochondria regulate the vast majority of your metabolism,” Glen explains. “And the super-interesting thing is they respond to light.”

Certain wavelengths, particularly in the red and infrared spectrum, appear to help mitochondria produce more cellular energy.

Modern lighting is very different from sunlight

Natural sunlight contains a broad spectrum of light, including ultraviolet and infrared wavelengths that our bodies have evolved with over millions of years.

But most modern indoor lighting — particularly LEDs — produces only a narrow slice of the spectrum.

“We’ve evolved under solar light for billions of years,” Glen says. “When we move into the built environment, we’re a long way from solar light.”

We may be experiencing ‘infrared starvation’

One of the biggest differences between sunlight and artificial light? The absence of infrared wavelengths indoors.

Glen and his team have even coined a phrase for this: infrared starvation. Researchers are exploring how this imbalance may influence metabolism, ageing and disease.

Too much blue light can disrupt metabolism

Many LEDs and artificial lights emit strong peaks of blue light — particularly wavelengths between 420 and 450 nanometres.

When that blue light isn’t balanced by longer wavelengths, it may affect how mitochondria function.

Glen says these wavelengths can “slow mitochondria down”, which may influence how the body regulates blood sugar and energy.

The simplest solution is also the best

While high-tech red-light devices are gaining popularity, Glen’s advice is surprisingly simple.

“Outside is best,” he says. This is because natural sunlight contains the balanced spectrum of light our bodies evolved to use.

“Get a dog — then you have to go outside twice a day!” says Glen.

Also in this episode:

  • Why infrared light is the most overlooked wavelength for human health
  • How LED lighting creates a “light deficiency” – and why Glen calls it modern-day scurvy
  • The profound effect light has on your mitochondria and energy production
  • Why morning light matters
  • What the research really says about red light face masks and infrared saunas
  • How changing your light environment could help regulate blood sugar and metabolism
  • The simple practical changes to make at home – and why Glen’s first recommendation is to get a dog

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