This article is part of our special report Lighting.
Until recently the lighting industry has focused on creating a lighting environment that facilitates the visual task, is integrated with the building architecture and fulfils requirements on sustainability and energy efficiency. However, recent research demonstrates the impact that the quantity and quality of light can have on human health and well-being.
One key impact is the disturbance of the biological clock and therefore of sleep patterns due to disruption to the Circadian rhythm. Indeed, for thousands of years, human beings spent their life mostly outside.
Exposure to the natural cycle of light in the past has forged a natural clock in us like all other creatures. To put it simply, bright intense daylight in the morning signals our bodies that it is time to start the day and conversely yellower, dimmer light in the evening tells us we are due for rest.
Most people have a biological clock either longer or shorter than 24 hours, which is tuned to the light of the sun’s daily cycle that daily corrects it to 24 hours. We call this the Circadian rhythm. In our modern lives, we spend more than 90 % of our time indoors, under electric light. In doing so we can severely disrupt this natural biological clock.
Lighting manufacturers and designers join forces to provide lighting quality, which takes into account variables such as colour rendering, vertical and horizontal illuminance, uniformity, glare and colour temperature, and generally to create comfortable and enjoyable lit spaces. It is clear that lighting needs to combine excellent visual, biological and emotional effects for human beings.
While electrical light in the past lacked the ability to mirror the intensity, timing, color and dynamics of natural light such as we know it, today the right lighting technology and design can take into account all the visual and non-visual effects of light to improve health, well-being and performance of human beings in the built environment.
“Human Centric Lighting” (or HCL) refers to lighting that brings such benefits to the users. For example, tuneable and dynamic LED luminaires, intelligent lighting systems together with dedicated lighting design can simulate the appearance and effects of natural light in a designed space. By including natural light, establishing light contrasts and changes in colours and intensities over time we can create, in humans, some of the circadian effects of natural light.
Light can improve cognitive performance and mood, it can energize, increase alertness or ease relaxation. Practically, this means that lighting can be designed to support specific user needs, thanks to a combination of technology including sensors and controls that result in the right light at the right time and at the right place. Working and living in a healthy environment is an important aspect of our daily lives. Ensuring that buildings become healthier and more energy friendly should thus rightly be a key concern for the EU.