Lighting is key to human life and it affects wellbeing in several different ways.
This is becoming increasingly recognized in lighting design and the latest evolution in the field is the so-called Human Centric Lighting.
Human Centric Lighting has been one of the lighting innovations seen at Euroluce 2019 and is part of the WELL Building Standard (opened in a new window/tab) – the international reference for interiors and buildings that focus on health and wellbeing.
Human Centric Lighting has been defined as
“lighting devoted to enhancing human performance, comfort, health and wellbeing”
Cit. Peter Boyce
To understand how and why it works, we need to take a step back and look at how we relate to light as human beings.
The impact of light on wellbeing
Light influences our overall wellbeing in 3 different ways:
- Visually, as it allows us to get a clear perception of the space around us and perform even meticulous tasks effectively.
- Biologically, as it influences our production of hormones, which in turn impacts on our sleep-wake cycle (the so-called circadian rhythm).
- Emotionally, as it affects our mood and overall comfort.
Natural vs Artificial
Sunlight is not static and varies during the day in both intensity and colour. From low and warm at dawn, to very bright and cool during the day, back to low and warm again in the evening.
The way our body works is strictly linked to the variations in natural light. In particular, exposure to cool light (or blue light) inhibits the production of melatonin (the hormone of sleep) and stimulates the production of cortisol and dopamine (the hormones that make us feel awake). Which is why we naturally feel awake during the day and sleepy at night!
These days, we spend 90% of our lives indoors, and this makes the quality and the effects of artificial lighting systems extremely important. Until now though, artificial lighting has never really considered wellbeing and – when compared to sunlight – standard artificial lighting tends to:
- Provide too little light during the day (about ¼ of natural light levels!) and too much light at night.
- Expose people to too much blue light at night time.
Overall this messes up with our hormonal balance, which is likely to cause sleep problems. And poor sleep can have a number of wellbeing and health consequences from bad mood and low memory, to lazier metabolism and immune system, up to cardiovascular diseases...just to name a few.
What Human Centric Lighting does is replicating sunlight variations in artificial lighting, creating a lighting system that:
- Provides optimal eye comfort
- Follows the human biological cycle
- Makes the environment comfortable and pleasant to live in
The knowledge about the effects of sleep on health has been around for quite a while, so it might be fair to ask why this Human Centric Lighting concept is gaining traction only now.
One reason is that today we have the technology and knowledge to make this both possible and efficient.
The introduction of LED lights has made spectrum tuning (i.e. making light cooler or warmer) easily accessible and the efficiency of LED allows adding sophisticated functions to standard lighting solutions without having energy bills skyrocket as a consequence.
Also, smart lighting technologies are making it extremely easy to control light. We can literally customize all the relevant aspects of light at the touch of a button!
On top of this, we now have a better understanding of how our sight works. In particular, experts have discovered the existence of a third light receptor in our eyes, which comes into play in the regulation of our circadian rhythm.
How does Human Centric Lighting work?
Human Centric Lighting acts on the 5 aspects of light, adjusting them for our wellbeing.
Just like sunlight, Human Centric Lighting fades up gradually when we wake up, shines bright during the day and gets – gradually – less bright as the evening comes.
This considers where the light comes from (overhead, wall flush etc.) and makes sure we get a comfortable environment without glare, dark areas or unwanted shadows.
Human Centric Lighting changes in colour (otherwise called spectrum content) during the day, delivering more blue light at daytime and getting warmer in the evening. For the records, this feature is often called tunable white.
Light colour also changes according to the time of the day. Sensors can detect the level of light outdoors and adjust indoor light accordingly, allowing considerable energy savings as a plus.
How long we’re exposed to light makes a difference. In particular, light exposure at night can affect sleep quality. Which is why light intensity should decrease as the night approaches.
Some examples of Human Centric Lighting
Let's finish off with a few examples of fixtures that reflect the Human Centric Lighting concept!
Cover image by Thomas Allsop(via Unsplash) (opened in a new window/tab)