Code Finder

Find the product codes you need by filtering from our whole product range.

Find Codes
Code Finder


Light and well-being: lighting to accompany our circadian rhythms

Interview with Maurizio Rossi, the Director of the Master’s course in Lighting Design & LED Technology at the Milan Polytechnic

Published: 11 Jul 2019
As a result of intensive telephone or tablet use, many people have now realised, at an empirical level, that our sleep-wake cycles are affected by the quantity and quality of light our eyes are subject to. However, it is not only intense, direct blue screen light (now often filtered by specific software) that influences our circadian rhythms and health, as we are also affected by the artificial lighting of the environments we live and work in.

In his latest book Circadian Lighting Design in the LED Era (Springer Nature, 2019), Maurizio Rossi, Director of the Master’s courses in Lighting Design & LED Technology and Color Design & Technology at the Milan Polytechnic, presents a number of theoretical and practical elements in favour of lighting systems that accompany our biological rhythms. To create a “zero impact” system, there are numerous variables to take into account, but thanks to LED technologies and the development of domotics, today, this target can be reached.
Light and well-being: lighting to accompany our circadian rhythms

Circadiam scheme

Lets begin with a definition of “chronobiology”.
Chronobiology is a science that studies biological functions which have a daily or similarly regular time span.

Did the Nobel Prize for Medicine awarded to Young, Rosbash and Hall in 2017 for their studies on Circadian rhythms, attract greater interest in chronobiology?
The main merit of that Nobel prize was to confirm the scientific basis of circadian rhythms. Previously, a lot of people were sceptical, not to mention those who simply confused circadian and biorhythms out of ignorance. The existence of the former has been proved scientifically for more than thirty years now, whereas biorhythms are simply a hoax invented in the 1970s in the United States to sell programmable calculators [here an old advert of a computer indicating a biorhythm calculation function, ndr].

The human circadian rhythm is a serious business. The general health of the individual depends on it, and it is affected by light. In the United States numerous studies are currently being conducted on this issue and what has emerged is that people who have difficulty regulating their circadian rhythms are more likely to develop a wide range of illnesses, including tumours.
The human circadian rhythm is a serious business. The general health of the individual depends on it, and it is affected by light.
So, is the aim to use artificial light sources that imitate natural ones?
I think the real target is to integrate natural light with artificial light when natural light is insufficient, or to use it completely when it is dark, to guarantee lighting cycles that are similar to those our ancestors had. Since the second industrial revolution, 90% of the population have ended up working in closed spaces instead of open ones or the country.

In addition to raising awareness of circadian rhythms, today we can also try to solve this problem, because we have the technology to do so.
Exactly: LEDs are a fundamental tool. These days it is certainly easier to achieve good or let’s say human-centric lighting that is based on the physiology of the individual and more efficient in terms of energy consumption.

At a concrete level, what needs to be assessed to create human-centric lighting?
First and foremost, the spectral composition of the light, as it is important to understand its chromatic content.

Are we talking about so-called light temperature?
Colour temperature is a useful simplification for describing the visual aspect of light, but natural white light is white because it contains all colours. However, some lights are seen as white, even if they do not contain all colours. Artificial light sources are required that have a more comprehensive spectrum and that reproduce a part of the characteristics of natural light, as, at present, it is impossible to reproduce them all. A second important aspect is that a good lighting system must be fitted with sensors to detect the degree of light in the environment (and the presence of people, as energy can be saved when no one is there). Whoever designs a lighting product cannot know what kind of environment it will be installed in, and light behaves differently in different locations, depending on the layout of the windows and the materials the furniture and floor are made of, etc. Light changes, even in the same environment. A person sitting near a window, for example, may pull the curtain slightly because the natural light is too strong and therefore uncomfortable. But this will mean that a person sitting a couple of metres from the window will receive a lot less light.

Yes, it’s true. It’s impossible to pre-program a system considering that a different type of light enters the same environment every day.
Exactly. Another fundamental element is that natural light is never the same and therefore artificial lighting must never be static either. It must be dynamic in terms of both colour temperature and direction. The first product at a worldwide level to be based on these principles was iGuzzini’s SIVRA (Automatic Adjustment Variable Lighting System), at the end of the 1990s.
Light and well-being: lighting to accompany our circadian rhythms

iGuzzini’s SIVRA (Automatic Adjustment Variable Lighting System)

But aren’t sophisticated solutions also extremely expensive?
Human-centric lighting is slightly more expensive, that’s inevitable, because there’s more Technology, like sensors, control systems, smartphone connections, IoT etc. We are talking about projects of a certain size, such as large workplaces, retail outlets or reception areas. It is therefore essential for the user to understand that this kind of lighting is good for them, but unfortunately, today, people are still very poorly informed. Users often aren’t aware that they even have a circadian rhythm and lighting designers know very little about these things. The best informed are those in Northern Europe and the United States.

What would be required to raise awareness?
Information. When newspapers report that the artificial lighting we have used for more than a century in our homes and workplaces is unhealthy and may have stimulated illnesses like headaches, migraines, diabetes, obesity, irritability and so on, then people will begin to worry. You can draw parallels with the food sector. In the 1970s, no one knew what organic produce was. No one gave it a second thought. Today, however, people are ready to spend a little bit extra to enjoy food with an “organic” label. It’s the same thing.

Do you think governments will pass legislation to encourage this transition?
I know there is an UNI commission on light and lighting and there are commissions at a European Union level too. In the United States a number of standards have already been defined, but in Italy there are still no standards governing the individual’s physiological well- being. Without doubt, a European standard establishing health requirements for lighting would help designers and companies significantly.