Humans Need Natural Light 

For millennia, the 24hr cycle of the sun was the only light we had. As a result, we evolved to rely on the sun's signal to set our circadian rhythm. 

This regulates our sleep-wake cycles, metabolism, hormone production and other physiological processes critical to human health. 

In modern society, where people often spend long hours indoors during the day and night, our relationship with natural light is broken.

Daytime artificial lighting is too biologically dim for our brains to get a proper daylight signal. This is coupled with artificial light at night, which is too biologically bright to signal our brains to prepare for sleep. 

This creates a misalignment, and the result has been termed social jetlag. 

The time to fix the issue is now.




What Is Our Circadian Rhythm & Why Is It Important?

The circadian rhythm we have is dictated by our internal body clock - the SCN. This circadian clock is kept in time by external light entering our eyes and is most sensitive at 490nm - the colour of our blue sky.

During the day, as our eyes are exposed to sunlight which stimulates our brain and signals our body to stay alert and awake. As it gets darker, our body produces melatonin to prepare our bodies for sleep, thus keeping our bodies aligned with day and night for optimal health.

To improve interior artificial lighting to fix this problem, first we need to understand what circadian lighting really is. 

Built to mimic the biological part of natural daylight, circadian lighting is spectrally tuned artificial light implemented to support the precise stages throughout 24hr.

Using the example of an office, where people spend long hours indoors during the daytime. Current standards and typical best practice in lighting design focuses on delivering visual light to perform a task as efficiently as possible. Typically little or no consideration is given to the human biological requirement. 

Specifically blue light at 490nm (good blue) has been engineered out of modern light fixtures to increase their efficiency at delivering light to the task. 

Studies support the effect blue light has on our circadian rhythm. Our bodies need this light as a signal to maintain a healthy circadian rhythm in a normal 24-hour pattern of a sleep-wake cycle. 

Recommendations now exist for how lighting designers can deliver truly effective circadian lighting to building occupants. This requires a combination of sky blue spectrum & optical control from the light fixture, integrated spatial design and lighting controls. 

In 2019 - experts in Chronobiology, sleep and light came together to make recommendations for the lighting industry to be able to follow. Energylight have adopted these recommendations as a pathway for the future of interior circadian lighting design. 

Check out the recommended daytime light exposure

The parameters of these recommendations are based on metrics provided by the CIE in CIE SYSTEM FOR METROLOGY OF OPTICAL RADIATION FOR IPRGC-INFLUENCED RESPONSES TO LIGHT

Recently leading figures in New Zealand health and wellbeing, have shared these recommendations in an effort to make a change. 

Check out this Stuff interview about new studies on light


How Does Circadian Lighting Work?

True circadian lighting can effectively be achieved from both a technical and cost perspective by considering Spectrum, Timing, and Placement.

Technology such as tunable Skyblue spectrum incorporated in light fixtures from Energylight & Energyline, used with integrated spatial design in pragmatic locations and combined with building lighting controls. The Skyblue spectrum should be at a high level throughout the day and reduced at night with minimal visual change. 

Brighter days, Darker nights - Biologically. 

To understand what's missing, we must review the spectral power distribution of a light fixture and understand the differences; this is demonstrated here:


Traditional 3500K LED spectrum vs Peak Circadian sensitivity.


SkyBlue Tunable spectrum LED - daytime.

SkyBlue Tunable Spectrum LED - night time.

Natural Daylight spectrum.


Solutions for truly effective circadian lighting require not just product. The following elements are essential for effective circadian lighting:

  • Skyblue tunable LED spectrum
  • Optical control to avoid glare and deliver vertical illuminance
  • Lighting & spatial design by Engineer or Lighting designer
  • Lighting control system to deliver circadian light at the right time


Want to learn more about Circadian Lighting and how to apply this to your project?

Contact our team today.



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