Beyond What We See - What Could This Mean for Lighting Design?

For decades, the lighting industry has understandably focused on visibility, efficiency and visual comfort, with conversations around lighting quality centred on factors such as light levels, glare control, colour rendering, contrast and colour temperature. But as scientific understanding of light continues to evolve, questions are emerging about whether lighting design may eventually need to consider broader biological effects.

In this interview, Professor Glen Jeffery shares what these emerging ideas could mean for architecture, indoor environments, and the future of lighting design.

Improving Spectrum Rather Than Replacing LEDs

LED lighting sits at the heart of modern lighting systems. When asked whether he saw the challenge as improving spectral balance rather than replacing LEDs, Glen made it clear that the conversation is not about abandoning the technology altogether but about exploring how wavelengths could be reintroduced into artificial lighting environments. In one example, he describes modifying a standard LED luminaire by incorporating an infrared LED alongside the existing light source.

“We’ve taken the standard luminaire LED, pulled it apart, and put an infrared LED in it,” he explains. The early findings, he says, have shown promising improvements in health in areas such as blood sugar control and visual function. However, Glen is careful not to present this as a complete answer.

For Glen, the broader challenge is to understand better how the spectrum of modern indoor lighting differs from the richer, more complex conditions of natural daylight — and how future systems might begin to address that gap.

Daylight, Buildings and Indoor Environments

Daylight remains the benchmark for healthy lighting environments, and as part of his research, he tried combining LEDs to simulate sunlight, but he hasn't managed to achieve it.

As buildings have become increasingly energy-efficient and environmentally controlled, he believes there may be value in exploring how modern indoor environments differ from the richer conditions humans evolved under.

One area he highlights specifically is glazing and the way buildings filter natural light. “Glass is another big issue,” he explains. “How can we get more infrared through a window while at the same time thermal regulating the internal space?”

Glen points to infrared-blocking glass as one example of how modern buildings may unintentionally alter exposure to parts of the spectrum humans historically experienced through daylight. His research highlights a link between countries where people spend most of their time indoors and diseases such as diabetes.

“Saudi Arabia has the highest rate, followed by Kuwait. This could be because these are countries that move from place to place with little or no sunlight and infrared blocking glass in their buildings.”

For Glen, this means future conversations about healthy indoor environments may need to be more holistic — considering not only how luminaires deliver light but also how buildings themselves shape and control the daylight people experience indoors.

Lighting Quality, Spectra and Biological Balance

Glen believes future lighting conversations may increasingly move beyond traditional measures of visual performance alone.

“In the next 5-10 years, we are going to be talking about spectra.” In this context, spectra refers to the different wavelengths that make up light — not only the visible wavelengths that determine how a space looks, but also the wider wavelengths present within natural daylight.

At present, much of the industry discussion around lighting quality centres on colour rendering, colour temperature and visual comfort. He believes future conversations may increasingly explore whether modern indoor environments are missing parts of the spectrum humans historically evolved with. “Have you got the right spectrum and are you delivering it at an appropriate power?” he asks.

Could Lighting Become More Dynamic?

One area Glen believes holds particular potential is dynamic lighting systems that respond more closely to human biological needs throughout the day.

While the science is still developing, he suggests future systems could potentially evolve beyond static lighting conditions toward environments that change spectrally and biologically over time.

Much of the research is still exploratory, and many practical questions remain unresolved. But he believes the direction of travel is becoming increasingly clear.  We asked whether future lighting systems could become more dynamic in supporting the body throughout the day. He said:

“The appreciation is beginning to get there,” highlighting his appetite for solutions that support the research. “This could eventually influence how workplaces, schools and healthcare environments are approached in the future — particularly in spaces where people spend long periods indoors.”

The Challenge for the Lighting Industry

The lighting industry may now be approaching an important turning point. He argues that one of the industry’s biggest challenges will be translating emerging biological research into practical, scalable lighting solutions.

That process, he acknowledges, is complex and expensive. Questions around spectral balance, intensity, timing and long-term outcomes remain far from fully understood. At the same time, he believes this also presents a significant opportunity for innovation.

At Fagerhult, we believe that wellbeing and human health should remain central to how lighting is approached. As our understanding of light and human biology continues to evolve, discussions like these offer an opportunity for the industry to explore how lighting design can support healthier, more thoughtful indoor environments in the future.