By Terry John of Photonstar LED
What is Human Centric Lighting?
Put simply, Human Centric Lighting (or Circadian Lighting) is where the intensity, colour temperature (CCT) and the spectral distribution of artificial lighting is adjustable so that your lit environment follows as closely as possible the natural daylight as it changes from morning to evening. This helps your body’s hormone balance to adjust naturally throughout the day so that you feel alert when required and sleepy and relaxed at the right time.
How does it work?
When the sun rises in the morning we naturally receive a dose of light in the blue part of the spectrum (typically around 460 to 480 nm). This encourages the production and release of serotonin which is the hormone which makes us feel alert and alive. This makes us feel ‘good’ and aids our concentration levels which, in turn, makes us more productive.
In contrast, as the sun sinks in the West, we naturally receive light that is much stronger in the red part of the spectrum. This allows the production of melatonin which is the hormone that encourages good quality and restorative sleep.
Why is it important?
As we are rapidly becoming aware, a healthy sleep/wake balance is one of the essential requirements for a happy, healthy and productive life. As ‘the Human Animal,’ our body clocks are still controlled and regulated by these daily changes in the light spectrum that we receive. If we are stuck indoors in an office, factory, school room, hospital or warehouse, our bodies still crave this daily cycle of short wave (blue) to long wave (red) light from morning to evening. If we don’t get this cycle however, it can upset our circadian rhythm and can cause us to feel listless during the day while reducing our ability to get a restful sleep at night. This can adversely affect our ability to concentrate which has Health & Safety implications when driving or operating machinery. So that can’t be a good thing, right?
How do we know it works?
Let’s be clear. We know that we all have non-visual receptors (the retinal ganglion cells) that receive light signals and transmit to the pineal gland which controls our hormone production. In addition, there have been several studies in various situations as schools, workplaces and hospitals as well as numerous studies under laboratory conditions which have clearly demonstrated the positive effect that dynamic lighting can have on our emotions and feelings. It is known that the light that we receive daily has an important influence on our physiology and our attention is being drawn to how we may now use lighting, along with other biological triggers, to improve our feelings of health and wellbeing whatever your daily routine may include. But (and this is a BIG but) we must also be aware that we are all different and each of us will also have different feelings depending on the time of day, the task we are doing or our general health. It is difficult therefore to pin down a quantifiable benefit which might satisfy an accountant! What we DO know however is that people who are benefitting from HCL report that they FEEL better – more alert, more productive and, well, happier!
How do you feel?
This simple question probably is the very best thing we could do! We acknowledge that our hormone production follows the rhythm of the day but of course there are various influences on how much we react to these stimuli at various times. This could be through our age, our metabolism, our physiology, illness or otherwise or just our general well-being. It can also be affected by such temporary issues such as a late night or two or any causes of stress at work or home. There is also the fact that various academics are querying the intensity of light exposure that is likely to have a significant effect on hormone production – some say you need exposure to 1,000lux (easily attainable outside on even a dull day) but others say that even exposure to the ‘wrong’ colour temperature at 30 lux for a period of 30 minutes or more can have an effect. This all leads me to conclude that the best indicator is that question ‘how do you feel?’
Bearing all this in mind what do we actually know?
Well, we know that our bodies react to different light spectra and that hormones significantly affect our performance either during the day or at rest.
We also know that emotion has a significant effect on how we feel – just think of how you feel in a scary film with dark lighting or how happy you feel on a bright sunny day!
The figures might be difficult to pin down as we are all different but one thing is for sure – light quality has a massive effect on our general performance and sense of wellbeing (or otherwise!).
Surely therefore it is incumbent upon all employers, schools, colleges, hospitals – you name it – to ensure that their lighting is as close to the natural environment as they can get it?
We have the technology and it is easy to apply and control and often confers other benefits such as reduced energy and maintenance costs over traditional lighting. So what’s stopping you?
Ask a lighting consultant or designer how such Human Centric lighting might benefit you or your organisation and you might be surprised.
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