How light affects our wellbeing
The city of Lights. Albe. Luci di domani - Ph. Ruggiero Scardigno
Ahead of Euroluce 2025, a conversation with Roberto Manfredini, Professor of Internal Medicine at the University of Ferrara. Finding out how the light-dark cycle regulates all our bodily functions
That exposure to natural light is one of the fundamental parameters of our psychophysical wellbeing is well known. Science tells us that exposure to sunlight carries various benefits, improving our mood as well as promoting the production of serotonin, guaranteeing a sufficient production of vitamin D for our daily needs and helping us to sleep well at night.
Light, artificial light included, is at the centre of our lives and regulates their rhythms. Not just as a source of illumination for indoor and outdoor environments - we also absorb a large quantity of light emitted by our smartphones, tablets and computers. Scholars have warned that we are spending increasing amounts of time in front of our displays, with clear negative effects, sparking more and more public debate.
Light, innovation, the evolution of the lighting sector, the changes and transformations, and the ways in which companies and lighting designers are facing up to the new challenges and the renewed needs for improving the quality of life of those occupying the spaces will be subjects for discussion at Euroluce from 8th to 13th April 2025. The International Lighting Exhibition will be an opportunity to reflect in the round, unveiling unprecedented ideas and proposals for lighting our homes – and other places – in the future.
We reached out to Roberto Manfredini, Professor of Internal Medicine at the University of Ferrara and Director of the UOC Medical Clinic, Sant’Anna University Hospital Trust of Ferrara, one of Italy’s leading experts in chronobiology, to discuss the new frontiers and broader perspectives when it comes to light.
The alternation of light and dark is the synchroniser of life, of the environment and of the Earth. In biology, all living things, plants included, are regulated by this cycle. Since the nineteenth century, just 200 years out of the four billion in which there’s been life on Planet Earth, artificial light has made it possible to illuminate rooms 24 hours a day, with a consequent expansion of the world of work. All this has given rise to the great desynchronisers: jet lag, shift work and seasonal time changes. The latter, even though it’s just a matter of an hour twice a year, commits 1% of Europe's GDP to health expenditure, the equivalent of 131 billion euros. Personally, I was a member of the commission of experts that collaborated with the European Union in 2019, which arrived at the decision to abolish the change. To date, the debate between Member States is still ongoing. The final great desynchroniser is night lighting, known as Artificial Light at Night (ALAN): as of 2010, when the incandescent light bulb was retired and LEDs were introduced – less polluting, better performing and less expensive - urban lighting has gone from strength to strength. This brings to mind Italy photographed by night from the International Space Station by Samantha Cristoforetti and the 2016 World Light Pollution Atlas, which shows that in parts of Europe, the United States and Asia, 90% of inhabitants cannot see the stars and the Milky Way precisely because of luminous illumination.
From a scientific point of view, we know that if used during the evening, smartphones, with their luminous screens, prevent far more melatonin being produced proportionally than natural light does. There’s a very close link between sleep deprivation and metabolic disorders, causing alterations to our hunger and satiety hormone rhythms (Leptin and Ghrelin), activating the stress hormone cortisol, and consequently lowering our sugar tolerance, which in the long term can trigger metabolic disorders or, in more serious cases, diabetes. This tells us that using light incorrectly can have extremely negative consequences, especially in young people. A 2016 study showed that 95% of American youngsters use their devices an hour before going to sleep, which has a direct correlation with the high rate of childhood obesity.
Synergy between the world of science, manufacturers and designers is fundamental, and is precisely why I gave a number of lessons, along with Stefano Capolongo, Professor of Hospital Design and Urban Health at Milan Polytechnic University, to architects, engineers, doctors to ensure that awareness of the use of light in the context of our health became part of the creative and design process. It’s an important factor because it is geared to disseminating scientific and clinical knowledge to integrate into design, and is a constantly evolving element that helps to improve the quality and wellbeing of our lives.
Speaking of public spaces, there are a lot of projects under way at the moment because the subject is slowly making its way into the agendas of our institutions. In Ferrara, for example, a project to train light flows downwards was carried out, with a view to curbing light pollution. Entitled “Torniamo a vedere le stelle” [Let’s See the Stars Again], it made it possible to install new LED lights directed downwards, making for up to 70% greater efficiency. Looking abroad, the Netherlands is another virtuous example, which has redesigned urban and street lighting geared to greater sustainability. As regards the private dimension, these days home automation has made it possible to achieve lighting similar to the physiological kind. The morning light is able to synchronise the body for the rest of the day. This means that it’s important to use light sources reminiscent of sunset during the evening, by means of dimmerable, warm toned LEDs.
Certainly. It’s a matter that concerns not just the wavelength of the light flows, but also the temperature of the light sources. If we look at healthcare facilities, for example, patient needs and priorities need to be taken into consideration. When treating Alzheimer’s, for instance, it’s important to use white light during evening hours because patients with cognitive decline tend to sleep during the day, so you have to restore correct circadian rhythm by means of careful use of light. The same reasoning is applied within cardiology areas, where light is modulated in relation to the pathology: this is because some light spectra, the coldest ones in particular, can trigger inflammation.
The principle behind the LED is precisely this: less pollution and lower consumption costs. I believe the key lies in dissemination and consequently in our awareness of how we use light, being mindful of its impact on our health and our wellbeing. Speaking of innovation, the virtuous example of Corgan, an American company specialising in airport construction, springs to mind. Last year it was awarded the contract to build a new 100-gate terminal in Shanghai that will be designed according to the circadian rhythm. The human-centred design approach puts people at the centre – all the lighting is modular and respects the human organism to reduce travellers’ psychophysical stress.
