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Three Approaches to Human-Centric Lighting
June 01, 2022

Our circadian rhythm (approximating a 24-hour cycle) is like an internal “clock”, regulating our biological functions depending on light levels (and the corresponding signals sent from our eyes to our brain). This in turn impacts our daily waking, eating, and productivity cycles. Any disruption negatively affects these functions—and especially disrupts the timed release of melatonin, which provides the sleep/wake signals to the body—leading to various physical and mental health problems. A daily light-dark pattern in the form of ample daytime light and extremely dark nights can enhance nighttime sleep—improving overall mood, well-being, and most chronic health issues.

The color, spectrum, intensity, direction, and the duration of exposure of light can have an effect on our daytime energy levels and nighttime sleep quality. Ideally, daily exposure to natural daylight—either by spending most of the day outdoors, or from close proximity indoors to filtered light from windows—is the optimal way to help our biological functions to stay on track.

Unfortunately, most indoor spaces lack properly-designed windows or even skylights. The main sources of light are from predominantly electric systems, which can be too dim or fixed to provide effective daytime stimulation, or conversely too bright after sunset to allow for a good night’s rest.

Circadian-effective human-centric lighting not only targets our eyes’ visual-based photoreceptors to add brightness and contrast, but also targets non-visual photoreceptors to promote stable circadian rhythms, aid in the timely release of melatonin, and mirror natural day/night cycles. Such systems should also ensure that sufficient daytime light is falling vertically on the eyes (current research recommends at least 350 Ix during the day and less than 30 Ix during the night).

Most manufacturers utilize one of three ways to implement human-centric lighting:

Intensity Tuning – The most cost-effective method, in which luminaires maintain a fixed correlated color temperature (CCT), but the brightness (intensity settings) can be adjusted using dimming controls. Ideally, lights should be programmed to turn on at a lower intensity in the early morning, switch to a higher intensity during peak daytime hours, and dim down as it gets dark—similar to natural daylight progression.

Color Tuning – Users can change the intensity, while also having the ability to change the CCT—warmer whites in the early morning and before sunset; cooler/bluer whites during peak daytime hours or in designated spaces—to try to be more in tune with the changing “colors” of sunlight over the course of the day.

Stimulus Tuning – Recent research has established that our circadian system achieves peak sensitivity in a ‘sky blue’ (around 490 nm wavelength) region of the visible spectrum—which sends the strongest circadian signal to our brains to help reduce chronic sleep and health issues related to perpetual “indoor lifestyles”. Such spectrally-optimized sources create white light with high circadian stimulus during the day (targeting non-visual photoreceptors in our eyes) without necessarily changing the CCT, thereby closely mimicking the natural daylight spectrum. Stimulus tuning systems should reduce this “blue” peak during the evening (ideally along with intensity tuning) to limit melatonin suppression.

Sensitively designed human-centric lighting systems can provide better sleep due to “brighter days and darker nights”—which in turn leads to better productivity, well-being, and overall health benefits for a wide range of applications (including workplaces, nursing homes/senior centers, residences, healthcare facilities, and educational institutions).

Advanced search functionality on LightAZ enables you to find the human-centric lighting solutions suitable for your application. Start your search today!