Designing light for healthier lives

New technologies are helping drive understanding of the biological effects of light on human health, transforming global standards in health, design and policy.

Light doesn't just help us see - it regulates our body clock, influencing sleep, mood and wellbeing. But in a world of artificial lighting and constant screen exposure, natural rhythms are increasingly disrupted.

To tackle this, researchers have developed technologies that measure light's biological effects. These tools are shaping policy and practice worldwide, from healthcare and urban design to animal welfare.

Beyond brightness: measuring light biologically

Traditional lighting measures like lux are based on human visual perception. But this overlooks the non-visual effects of light - especially how certain wavelengths, like blue light, interact with light-sensitive cells in the eye that control the circadian rhythm.

When people are exposed to bright, blue-rich light in the evening, it can delay sleep, disrupt hormonal cycles and increase the risk of long-term health issues including diabetes, depression, and heart disease. Yet until recently, there was no practical way to measure these effects.

That changed with the development of α-opic equivalent daylight illuminance (EDI) - a new international standard that quantifies how light influences non-visual pathways in the body. Researchers helped shape this standard, which is now embedded in the global guidelines, informing best practice in lighting design and regulation.

Technology for everyday use

To make these standards usable beyond the lab, researchers developed a suite of wearable light sensors and a free online tool to calculate real-world EDI exposure. These technologies allow for day-to-day monitoring of biologically meaningful light levels across homes, workplaces, schools and healthcare settings.

Data collected using these tools shows that most people are routinely exposed to poor lighting - when lighting is too dim during the day, and too bright at night. This has direct health and economic consequences. Poor sleep is forecast to cost the UK economy 2.1% of GDP annually by 2025. In the United States, even modest improvements in sleep patterns could result in over $300 billion in annual GDP gains.

Findings from this work are already informing how lighting is specified and implemented in buildings to promote sleep quality, concentration and overall wellbeing.

Global relevance and scalable solutions

Designed for affordability and adaptability, these tools are suited to low-resource settings and scalable across a wide range of environments. They support public health initiatives and evidence-based interventions in both high- and low-income countries.

The technology also has applications in animal welfare. Researchers have created species-specific models for measuring biologically effective light exposure in animals, supporting better standards in agriculture, labs and conservation.

Informing policy and environments worldwide

This research is already influencing international guidance across healthcare, education and urban planning. It equips governments, designers and regulators with tools to create lighting environments that actively support wellbeing, productivity and sleep.

By translating cutting-edge science into scalable, real-world technologies, this work is redefining how light is measured, and how it can be used to create healthier environments for people and animals worldwide.