Did you know that light does far more than just help us see? In our recent “Meaning of Light” series, Dr. Geoffrey Guy and Alistair Nunn of the Guy Foundation took us on a fascinating exploration into the profound and often overlooked connection between light, quantum biology, human health, and even our potential for space travel. Their message was clear and compelling: light is a fundamental force in biology, shaping everything from the intricate workings of our mitochondria to the very process of ageing, both here on Earth and beyond.

Dr Geoffrey Guy, a pioneer in cannabinoid research and a leading voice in quantum biology, kicked things off by highlighting the often-underappreciated power of photons in human biology. He emphasised that modern indoor environments—dominated by artificial light and insulated from natural infrared—may be quietly undermining our health. The Guy Foundation, established in 2018, aims to bring attention to such overlooked biological fundamentals by bridging the gap between physics and medicine.

Alistair Nunn then took us on a rather compelling journey through the science of mitochondria. He detailed how light, particularly in the infrared spectrum, influences mitochondrial health and therefore, overall metabolic resilience. Mitochondria don’t just power our cells; they regulate inflammation, determine how cells respond to stress, and may even emit their own biophotons as part of an internal regulatory mechanism.

He posited that ageing may partly result from being chronically out of sync with the evolutionary “Goldilocks zone” for light exposure. Our mitochondria evolved under specific environmental conditions, including a full spectrum of natural light, and depriving them of these cues may accelerate dysfunction and disease.

Perhaps the most fascinating part of the talk was its implications for space travel. In space, humans are deprived not just of gravity, but also of Earth’s protective magnetic field, atmospheric pressure, and full-spectrum sunlight, especially red and infrared light. NASA research already shows astronauts experience accelerated ageing, mitochondrial dysfunction, and immune changes. Could disrupted light exposure be a root cause?

Nunn discussed how correcting this with artificial lighting that mimics Earth’s spectrum, especially the inclusion of red and near-infrared wavelengths, might protect astronaut health and slow down the effects of ageing in space.

But this isn’t just about astronauts, not at all. As Nunn and Guy noted, most people on Earth now spend around 90% of their time indoors under blue-heavy LED lighting. This “infrared starvation,” they argue, may be quietly impacting public health, contributing to chronic inflammation, metabolic disorders, and reduced resilience to stress.

Their recommendation? Re-evaluate the lightscape in our homes, schools, hospitals, and offices. Incorporating more naturalistic lighting—with attention to spectrum, intensity, and timing—could be a low-cost strategy to enhance healthspan and reduce the burden on healthcare.

If you missed this rather thought-provoking discussion or any of our previous sessions, head over to our YouTube channel.