Circadian Light: What Is It & Why Should You Care?

How does circadian light work?

There are three ways to implement a circadian lighting system: intensity tuning, color tuning, and stimulus tuning. 

Intensity tuning involves maintaining a fixed correlated color temperature (CCT) and adjusting the intensity (brightness) of the light through a controlled dimming system. This gives you the ability to transition between lower lighting intensity in the early morning, higher intensity as the day progresses, and the lowest intensity in the evening. 

Color tuning involves adjusting the CCT to mimic the natural oscillations between light during the daytime and darkness during at night. During the daytime, when the sun is at its highest point in the sky, we experience cooler color temperatures (from 4000K–10,000K). This is typically when we feel most alert. So, cooler CCTs are most effective to use in designated spaces (and at certain times) when you need to feel energized and focused. Warmer (redder) color temperatures (from 1000K–3500K) more closely represent what we experience when the sun rises and sets.  

Stimulus tuning is lighting technology that emits light in your circadian system’s peak sensitivity region (near 490nm) (2).  It essentially replaces the “bad blue” that can cause retinal damage with “good blue” light wavelengths that entrain circadian responses.  Stimulus tuning fixtures can be programmed with dimmers to either infuse or minimize the amount of blue light they emit depending on the time of day.  That means you can proactively transition between promoting alertness in the daytime and preparing your body for sleep at night.

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