What is Human Centric Lighting?

Human Centric Lighting (HCL), also known as circadian lighting, or lighting for health and wellbeing, is a hot topic amid lighting designers and scientific researchers alike. The basic idea behind what some would regard as a philosophy is this: since the dawn of electric light, humans have been able to “see” whenever they want to. Daytime and night time mean nothing, and lights can be on full blast 24 hours a day if we would like them to be. While historically speaking, electric lighting is considered a major technological advancement (we no longer have to go to bed at 5:30 pm in the middle of the winter!), many studies also show the negative effects electric lights have on our body’s circadian rhythm. (Our physical, mental, and behavioral changes that follow a daily cycle.)

These rhythms respond primarily to light and darkness within our environment and working under certain kinds of light during the day can have a direct impact on how well we sleep at night, our personal health, and even our emotional stability. Human circadian studies have increased in research and importance, as evidenced by three US scientists recently receiving the Nobel Prize in Physiology or Medicine for their work explaining how the circadian clock works.


LEDs and Human Centric Lighting

Many of the recent articles and studies that surround Human Centric Lighting cite LEDs as the driving force. They can deliver light at made-to-order color temperatures, spectral power, color, and brightness. Luc Schlangen, senior principal scientist at Phillips Research is quoted in LED Magazine as saying, “Human-centric lighting is about being able to personalize and control your lighting to suit your needs and increase your wellbeing”. The importance of the control afforded by LEDs is key for Schlangen as their digital nature makes them relatively easy to tune to settings that might support human circadian needs.

Through the Internet of Things, our lighting can be controlled and customized in real-time. Office lighting fixtures can be connected to a building’s IT network and employees can control their own light levels and color temperatures using smartphones and digital applications. (Read more about the advancement of digital lighting controls and the cloud here.) As such, Human Centric Lighting can be used to stimulate people during the day (with bluer frequencies) and relax them at night (with amber and red frequencies). While daylighting has been proven time and time again as the best source of interior light for productivity and health sake, Human Centric Lighting, through the use of LEDs, can be tuned to the same levels of light that the sun delivers, reinforcing our natural circadian rhythm.

The ideas behind human centric lighting are applicable across the board – in offices, factories, warehouses, schools, hospitals, homes – you name it. A notable study was recently published in Europe that tested Human Centric Lighting in many of these spaces with results that very much support this movement to make lighting a more natural part of our day. Here are two examples pulled from the article entitled: Research Assesses the Value of Human-Centric Lighting, from LED Magazine.

In industrial settings: the study looked at a factory of 750 workers performing repetitive tasks. Typical LED-based factory lighting was replaced with 2000-lx LED lighting. It was found that while annual electricity costs rose from €42,000 (approximately $47,000) to €54,000 (approximately $60,000) for HCL, the effect was that productivity increased by 4.5%. The study also reports fewer accidents (1%) due to increased alertness, together with 1% fewer sick days, and one-year improved retention of staff.

 In education, the study looked at a school with 1,000 pupils and 80 teachers. The annual electricity costs rose from €8,000 to €11,000 (approximately $8,900 to $12,240) when HCL was installed. Following installation, there was a 15% improvement in cognitive performance in some pupils and a 10% reduction in the healthcare and education costs of the 5.3% of pupils suffering from ADHD (attention deficit hyperactivity disorder). From a staff perspective, there was also an 18% improvement in efficacy for mental disorders, which had accounted for 11.7 sick days per teacher (as a result of stress and burnout) and employees’ duration at the school was extended by two years.

Of course, lighting isn’t the only common environmental factor that’s affecting our circadian cycles. Heating and air conditioning (temperature), physical activity or lack thereof, eating habits, and much more all play a role. Regardless, our world is now comprised of people who spend the majority of their time inside amid bright lights no matter the time of day – and this is impacting our health. Scientists will continue to study lighting’s circadian effects, and how LEDs can support human health improvement both within the workspace and our homes as well. 

To learn more about Human Centric Lighting, check out the following resources:



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