Human Centric Lighting
– The 5th Layer

by Beatrice

The way we think about lighting is changing. 

The importance of light has evolved beyond how we see things – increasingly we are beginning to understand that light has a huge impact on almost every aspect of human function.

Research has shown that light has a direct impact on human psycho-physiological processes such as mood, performance, sleep regulation, hormone release (like melatonin and serotonin), eating behaviour, and even disease. Without a proper circadian rhythmicity – the 24-hour cycle in the physiological processes of all living beings – humans are increasingly prone to conditions such as cancer, diabetes and cardiovascular disease. Light, be it natural or artificial, is a key factor in circadian regulation. This goes beyond the pure visual aspects of light.

It is important to distinguish between light, the physical phenomena, and lighting, the delivery of light and the domain of architects and lighting designers. Today’s challenge is to integrate the non-visual characteristics of light into adequate lighting solutions, and for this purpose, the International Commission of Illumination (CIE) has introduced the term Integrative Lighting.

This is defined as “lighting specifically designed to produce a beneficial physiological and/or psychological effect upon humans, including both visual and non-visual effects” and is the formal term for Human Centric Lighting (HCL).

Increasing the application of HCL has become a critical consideration for the architect and urbanist but it is about much more than lamps and fixtures and energy: it is about IT, science and design, and working with researchers, scientists and manufacturers to translate the emerging knowledge into actionable benefits to our daily lives.

Here lighting designer and architect Daniela Viloria, based in Broadway Malyan’s Madrid studio, talks to Dr Octavio Pérez, Adjunct Researcher at Mount Sinai Hospital in New York and HCL Translational Scientist at Lledó Group, about his transformational work in the field and the impact light can have on human wellbeing, health and happiness.

Octavio, in simple terms, what is the relationship between light and the human circadian cycle?

Think about human life and evolution on planet Earth. Our life and our biology are critically conditioned by the dark/light cycles of the day on Earth due to the rotation of the planet around its axis. We have evolved under this rhythmicity. Light is associated with activity, and darkness with relaxation, recovery and sleep. This is our natural cycle, and it is deeply imprinted in our biology. Our eyes receive visual and non-visual (melanopic) light stimuli, and we have ambient, task, accent and decorative layers of lighting, all on the visual side. We should begin to think about HCL as the non-visual fifth layer of lighting.

As designers, we need to have a clearer understanding of how this impacts our daily performance. Looking at specific sectors, how could ‘Smart Cities’ evolve with the application of HCL principles?

This is a clashing question. On one hand we have societal evolution that runs on a 24/7 basis. Smart cities, and smart lighting, can definitely contribute to this development, adding safety, information and control to our lives. But we also have to consider that this scenario can radically disrupt our natural life rhythmicity. Adequate light spectrums and intensity, together with a reduction in glare, are critical for proper lighting in the human/natural biological night, in cities and in rural environments. We have to be respectful to ourselves and to nature. Keep in mind that darkness is the optimal biological light at night, and we are losing darkness in these modern times.

Since it is a health issue, are there any studies on HCL in the healthcare environment? 

Sure. The effects of light on human health have been known since antiquity. The Egyptians and Greeks knew about it, think about the term “solarium”. Coming into more modern times, Florence Nightingale, the founder of modern nursing, highlighted in ‘Notes on Nursing’ – published in 1859 – that light was a critical factor for healing. Dr Niels Ryberg Finsen won the Nobel Prize in Medicine in 1903 based on his discoveries about light and health. There are numerous scientific papers and studies in the field, and perhaps the title of the 1998 paper from Beauchemin ‘Dying in the dark’, is self-explanatory. In the particular case of healthcare, it is not only about basic science, but about Evidence Based Design – the “process of basing decisions about the built environment on credible research to achieve the best possible outcomes” (as defined by the Center for Health Design). Proper lighting design can improve patients’ recovery, reduce medication, and reduce length of stay in hospitals. Daylight is critical but lamentably we have moved from heliotherapy into heliophobia. I have participated in studies where we have observed a reduction of up to 35% in the length of stay depending on the patient room orientation. My doctoral dissertation was about the influence of lighting in clinician wellness and performance, to reduce clinician burnout and medical error, and improve patient safety. This opens the application of lighting in the field of “Healthcare Ergonomics”.

If we consider good lighting practices as preventive health, how should we consider artificial lighting in schools and workplaces where we spend most of our time?

The first approach has to be to maximise daylight, our evolutionary driver. When daylight is not available, then artificial light makes an important contribution. Nowadays we have full spectrum LED sources that closely resemble the indoor daylight spectrum and we can get rid of bad quality lighting sources. Think about the sleep and myopia pandemics – light, and darkness, can be a huge contributor to improve both. Light is a drug without side-effects, if properly applied, that can contribute to enhance our ‘sleep hygiene’ and therefore our performance and quality of life, from teenagers right through to the elderly.

Since one of the biological systems regulated by the body clock is wakefulness and sleep, could hotels offer a circadian-friendly experience?

Of course, and they should. I travel worldwide and there is nothing worse than hotel lighting. And you raise a good point! The challenge here is about the user interface/experience – it has to be easy to operate, standardised and the same as in other environments, particularly healthcare. User experience is the most challenging side of HCL design. 

FAN Mallorca, Spain

Science, industry and marketing are not always aligned. Is the lighting industry working to provide us with new fixtures that consider melanopic light?

The lighting industry is experiencing a tremendous paradigm shift, as the writing machines were in the 70s and 80s. We have to think that light fixtures are like printers, they imprint light into our ambient and architectural spaces. To do this properly, we need good printers (light sources, optics, etc), but a new key question is control and software. IT is going to be the next step in the lighting industry, and all the stakeholders should be aware and evolve with it. Nowadays, lighting is part of the MEP (mechanical, electrical, plumbing) budget in buildings. This means price driven and low value. It has to shift to IT for the value to be recognised and explored. Technologies such as PoE (Power over Ethernet) will certainly contribute. It is not only about hardware and software – proper design will complete the loop of actionable HCL lighting so that it is properly integrated with the built environment.

And what about government institutions, are they aware of the potential of light to improve performance, quality of life, wellness and even reduce costs of the healthcare systems?

In my opinion, society remains highly illiterate in the understanding of light and lighting and the same is the case for governments and public institutions. The field has been captured/sequestrated by the lighting manufacturers, as happened with the Phoebus cartel in 1924 where the useful life of the incandescent bulb was programmed to just 1,000 hours. Education and awareness is needed to really articulate the benefits of lighting for society to the widest possible audience, particularly in terms of HCL. There are ethical questions that will arise soon, and these must be anticipated – lighting designers, scientists and manufacturers are not doctors. We should expect regulations in the near future and there are building standards that are beginning to recognise circadian lighting.  

Related Content

We use cookies to enhance your browsing experience to deliver to you the best quality browsing experience. Accept Cookie policy