LIGHTING
Light and health: beyond compliance
Evidence suggests that LEDs might be causing harm to our cells – meaning that the health of the population is being adversely affected by spending lots of time indoors without daily exposure to daylight or full spectrum lighting. However, there are measures that designers and facilities managers can take to improve the situation, as Lorraine Calcott, director and principal designer at it does Lighting Ltd, explains.
For centuries, sailors suffered from a mysterious decline in health during long voyages. Fatigue, poor wound healing, cognitive decline, and premature death were common. The solution, once discovered, was almost embarrassingly simple: citrus fruit. The absence of one essential nutrient had silently undermined human physiology. Today, we may be facing a parallel problem. Not with vitamin C, but with light. Modern healthcare estates are extraordinarily efficient. Energy targets are met. Maintenance cycles are optimised. LED systems deliver consistent illuminance with minimal power demand. On paper, this looks like progress. But what if we have engineered a different kind of deficiency?
The spectral shift no one talks about Over the past decade and a half, lighting has undergone the fastest technological transition in its history. Incandescent and discharge sources, rich in longer wavelengths, including red and near infrared, have largely disappeared. In their place sit blue-based LED systems engineered for photopic efficiency. These systems are not ‘bad’ – they are compliant,
controllable, and efficient. However, they are spectrally incomplete. Most white LEDs are built upon a high-energy blue pump. Phosphors convert part of this into longer wavelengths, but near-infrared content, present in natural daylight and traditional thermal sources, is largely absent. In the drive to maximise lumens per watt, we have optimised for the visible response of the human eye, not the full biological response of the human body. That distinction now matters.
Light does more than help us see The science of non-visual light effects is no longer emerging – it is established. The International Commission on Illumination (CIE) formalised this through CIE S 026, recognising melanopic and other photoreceptor influences on physiology. Subsequent technical notes and workshops have reinforced the need to consider biological light exposure alongside visual metrics. Similarly, European technical developments through CEN and national standards such as DIN/TS 67600 have begun embedding non-visual criteria into lighting guidance. This is not fringe science – it is standards-level evolution. The IALD (International Association of Lighting Designers) European Regulatory Affairs Working Group
recently published Lighting Design for Health, Wellbeing and Quality of Light – A Holistic Approach to Integrative Lighting White Paper. The document is clear: lighting that focuses solely on visual metrics is incomplete. Integrative lighting must balance visual, emotional, and biological effects.
And that is before we even address mitochondria.
Natural daylight includes red and near-infrared wavelengths.
Healthcare estates teams routinely commission specialists for fire engineering, acoustics, and infection control. Lighting deserves similar scrutiny.
April 2026 Health Estate Journal 51
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