Human centric lighting (HCL) is a concept that brings natural daylight into everyday life through effective artificial lighting. It helps people to stay aligned with the natural circadian rhythms that we have adopted since time began. It is lighting that is in tune with our deeply ingrained sense of light and dark, day and night, awake or asleep - the lines of which are less distinctive nowadays.
If this sounds a little fanciful then consider that only 200 years ago our ancestors spent 90% of their time outdoors and were in complete synchrony with the earth’s changing cycles. With the advent of electricity and a reliance on artificial lighting we now spend very little time outside, comparatively, and we are far less exposed to natural light sources. The introduction of artificial light has led to a circadian disruption which potentially lies at the source of sleeping disorders, some illnesses and worse. The good news is that HCL can go some way to mitigate the negative effects of modern lighting.
Properly integrated, HCL will cleverly simulate the right time of day in our offices, work premises, homes, shops, restaurants – throughout the 24 hour clock. During the day, HCL emulates daylight and provides comfortable lighting for work. As the day draws towards evening and night time, so HCL changes to reflect this. The daytime light is designed to encourage wakefulness, productivity and learning whilst evening light takes us into a period of essential relaxation and regeneration.
The foundation of HCL is to help us navigate the way through our lives, minute by minute, hour by hour, allowing light to work in harmony with what we need to achieve at that moment. It provides solutions to physiological and biological requirements that, until recently, have been misunderstood. We have probably all been in households or work environments where changes are made as the lighting fades. We close blinds and curtains, select lighting according to our mood and needs and make the day to night transition - but much of this has been instinctive rather than technological. We probably also know of places that don't alter the lighting as the day progresses, preferring to maintain a semblance of daytime, especially if the evenings are a necessary time of productivity or study.
You wouldn’t light a bar at night in the same way you might do during the day for example. A bar in the day might be used for meetings, to watch sport, to gather after an event (pandemic permitting) or to have lunch - but a bar at night is more likely to be used for more intimate meetings where different lighting and music is expected.
Here’s the science bit, explaining what happens when the eye receives brighter light and how it makes us more alert and wakeful. Constantly living under the daylight emissions of a blue-based, higher intensity light will eventually lead to a reset of our natural body clock.
When the eye senses optical radiation at a higher intensity, the release of melatonin will be suppressed and the production of dopamine, cortisol and serotonin will be triggered. Dopamine is an endogenous catecholamine that is needed for pleasure, alertness and muscle coordination. Cortisol is a stress hormone that promotes wakefulness and makes people feel alert and active. Serotonin is a neurotransmitter that provides impulse control, enhances mood and motivation. [source: manufacturer.lighting April 2020]
The consequences of a disrupted arcadian cycle and a resulting suppression of melatonin secretion means that our sleep is altered to the point where there is potential for health risk and impacts on a number of hormone functions. A lack of sleep leads to fatigue and a reduced performance of course but it also affects our metabolism and cell regeneration. Studies have shown that disrupted circadian rhythms underpin many disorders including obesity, mental illness, cardio problems, diabetes and more.
HCL utilises energy-efficient LED technology which allows for finely balanced colour, intensity and timing to be applied to our daily lighting. When we connect HCL with smart buildings, the potential for control and design to light our lives and improve our health and performance is limitless.