Finding the Connection Between Tunable White and Circadian Lighting

Finding the Connection Between Tunable White and Circadian Lighting

Key Concept to Understand

Tunable white LED lighting systems afford us the ability to shift color temperature within a lighting fixture at-will, turning off one or a series of LEDs in the fixture.  The implications of this technology are clear: when we can shift the color temperature in a lighting system, it can restore our relationship with sunlight, changing the way indoor lighting affects us. Though, not all tunable white lighting systems are the same, which is why we cannot assume that they all offer the benefits of circadian lighting.

Let Sunlight Guide Artificial Light

SPD of daylight and sunet

SPD of natural daylight & sunset – NOTE DAYLIGHT peak at 482nm

To understand the differences between tunable white lighting systems and circadian lighting systems, and whether or not they can be classified in the same manner, we can start by looking at the SPD (Spectral Power Distribution) of sunlight, which describes the power of light at a given wavelength. Daylight SPD, as we will see, is extremely important to our circadian rhythms, the pattern of waking up and falling asleep that we follow every day.

Let’s think about what our most natural and healthy lifestyle would look like in terms of our circadian rhythm: we would take in sunlight during the day and then lay down in total or near-total darkness at night. When we lay down, our bodies produce melatonin as part of a natural reaction to the darkness, which keeps us running on approximately the same schedule as the sun.

In our modern world, we have disrupted this process completely. Most notably, we are now often substituting natural daylight with artificial light. Knowing how much we rely on daylight, it makes sense if possible to model artificial light after sunlight.

Blue Light is a Blight on The Typical LED

Energy-efficient and lasting almost forever, LED lighting has quickly become one of the more popular types of artificial light, but there is a secret about them that most people do not know: white LEDs are actually blue.

SPD of daylight versus LED

Daylight versus LED – NOTE BLUE spike at 450nm and trough at 482nm

It’s true.

White light from an LED is merely the result of a white phosphor coating placed over a blue LED.

When we look at and compare the SPD of LED light with the SPD of the sun (our model for healthy circadian lighting), there are some alarming differences in the “blue-light” region.

To illustrate this, compare the SPD graph shown of a typical LED with daylight; you see that there is a noticeable low point in the LED graph at 482nm.  This low point is important because science has proven that the non-visual ipRGC (intrinsically photosensitive retinal ganglion cell) receptors in our eyes are most sensitive to blue-light at this 482nm wavelength.

SPD of sunset

SPD of Sunset – NOTE low blue light level helps promote sleep

What this means is daylight from the sun helps to suppress melatonin, increasing our energy and productivity during the day.  Conversely, the blue-light level of sunlight during the evening is much lower, which encourages melatonin production and promotes sleep.

This is a good time to note that all blue light will suppress melatonin. Even the blue-light spike in a typical LED at 450nm will still disrupt your circadian rhythm at night. We cannot avoid that completely. A tunable white system using typical LEDs and trying for a circadian affect will need to make a compromise.  By adjusting the color temperature or just the light intensity, you will wind up either suppressing melatonin too little during the day or creating an uncomfortable setting high in glare and brightness.

This is because typical LEDs have a trough at 482nm and can’t achieve the power levels required to suppress melatonin without over-lighting a space and creating a glare. Take a typical neutral-white color temperature LED: if you want to use this to suppress melatonin during the day, you would need to “over-light” the space, creating glare that makes people uncomfortable.  If you choose a higher “blue-light” cool-white LED to suppress melatonin, alternatively, you would make people uncomfortable because of the blue-ish color temperature of 6500K.

A New Solution

Nichia Optisolis LEDs Used in PERFKETLIGHT

PERFEKTLIGHT uses high CRI Nichia Optisolis LEDs

It is true that LEDs represent the cutting edge of lighting systems, and tunable white lighting systems are the most innovative application of LEDs. There are distinctions that we need to draw, though: a tunable white lighting system is only as powerful as the LEDs that we find inside it. To enhance the impact of a tunable white lighting system on our circadian rhythm, we can look at the wavelengths that the LEDs are emitting.  Tweak the wavelength to the optimal point of 482nm and you can suppress melatonin without making anyone uncomfortable.

This is why tunable white lighting is such a major improvement over monochromatic white LEDs – by using the right technology, we can change the wavelengths, aligning them with the perfect wavelengths for your circadian rhythm. Next, let’s look at the specific and industry-leading way that we are accomplishing this.

The Impact of a 482nm Peak

Thanks to Nichia’s Optisolis LED, we have eliminated the trough at 482nm and filled it in with the optimal wavelength to encourage alertness. This may seem like a small difference from the wavelengths that you would find in typical white LEDs, but on the scale that your eye works, it is huge. Unlike typical white LEDs, which disrupt the circadian rhythm, the 480-490nm-peak wavelength that you find in Nichia’s Optisolis LED does not, as it suppresses melatonin during the day but facilitates low blue light in the morning and evening.

PERFEKTLIGHT SPD with Nichia Optisolis LEDs

SPD of PERFEKTLIGHT – NOTE low blue light level of warm color temperature for morning and evening versus the higher blue light level of neutral and cool-white color temperatures during daytime

When we compare Nichia’s Optisolis LED with typical white LEDs, we see that it is minimizing the blue peak and trough. On top of that, it equals the SPD of sunlight without emitting any UV radiation. For art galleries and museums, which need to avoid UV because of its damaging effect on their art and artifacts, this is good news, just as it is good news for you as you work to keep your circadian rhythm timed properly.  Thanks to tunable white lighting featuring Nichia’s Optisolis LEDs, you can take charge of your circadian rhythm, discover all the sleep that you have been missing, and step into a new and healthier life for yourself. You can wake up each morning feeling refreshed and energized, laying down in your bed at night confident that sleep troubles are not going to keep you from the rejuvenation you need.

LEDdynamics, PERFEKTLIGHT, and You

At LEDdynamics, we believe wholeheartedly in working on the cutting edge science in the lighting sector. That is why we have not only pioneered tunable white lighting – we have also sourced our LEDs from Nichia, refusing anything but the very best, knowing the impact that our tunable white lighting systems can make on all of our customers. Researching these LEDs extensively, we are championing a new ideal in tunable white lighting through PERFEKTLIGHT.

Contact us about PERFEKTLIGHT

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