What is Human-Centric Lighting?

As a relatively new term, Human-Centric Lighting (HCL) may not yet offer a concrete definition, but the term describes lighting designs aimed to benefit human health and well-being. HCL intends to improve performance, comfort, and health through lighting. While much remains unproven about the effects of human-centric lighting, the end goal to benefit office workers’ and occupants’ health remains.

Human-centric lighting mainly concerns lighting’s effect on circadian rhythms. The National Institute of General Medical Sciences (NIGMS) defines circadian rhythms as “physical, mental, and behavioral changes that follow a 24-hour cycle.” One circadian rhythm, regulated by the body’s biological clock, controls the natural sleep-wake cycle. NIGMS cites the light from an electronic device as a factor that can confuse this biological clock and cause sleep disorders. Sleep disorders can lead to chronic health issues such as “obesity, diabetes, depression, bipolar disorder, and seasonal affective disorder.”

Human-centric lighting seeks to avoid these issues. Because many types of lighting, like fluorescent and LED, as well as phone and computer screens, give off blue light, we’re often exposed to too much blue light output during the day. This blue light reduces melatonin production and makes it harder to fall asleep. To combat this, HCL adjusts the color temperature of lights in offices and work environments to mimic natural light instead of the static, electric light we’re used to. These environments use productivity-boosting blue light in the morning and, as the sun begins to lower, gradually switch to a warmer color temperature. In theory, this keeps you productive throughout the day and improves sleep at night.

HCL in many work environments relies on LEDs, specifically tunable or SMART LED lighting. Tunable lighting offers control of the color or color temperature of the light emitted from the light source without affecting the brightness. This requires the use of different color temperature LED chips included in the same bulb.

The Correlated Color Temperature (CCT) measures the color of the white light emitted by a light bulb in Kelvins (K). They fall on a scale between 1000K-10000K. The lower the light bulbs land on this scale, the warmer the light appears. The higher they land, the cooler, or bluer, this light appears.

A few types of LED tunable options exist, such as:

• Dim-to-warm: as the light dims, the color temperature becomes increasingly warmer.
• Tunable-white: changes the color temperature of the white light from warm red tones to cool blues. The color temperature ranges from a warm white to cool white. Sometimes referred to as intensity-tuning.
• Full-color tuning: changes the primary colors of the light across the entire lighting spectrum. This changes the color emitting from the light from white to almost any color on the spectrum.

HCL and circadian lighting mostly use tunable-white bulbs or fixtures. This allows the user to adjust the color temperature as the day progresses.

Similar to dimmable lights, tunable lighting systems offer a few different control options. Some control systems allow you to adjust the temperature using a manual or touch-sensitive configuration while others use SMART technology. SMART bulbs connect to a SMART hub and may connect to Wi-Fi, Bluetooth, Zigbee, or another signal allowing you control over lighting from almost anywhere. Certain controls can even program the lighting to change throughout the day.

The Lighting Research Center at Rensselaer Polytechnic Institute (LRC) states that lighting designs for the non-visual aspects of lighting require different metrics than simple architectural lighting. This means you’ll have to consider more than just how the lighting looks. The LRC proposed a metric called circadian stimulus (CS) to create lighting designs for healthy buildings. They state that, when using lighting to affect the circadian system, you should consider “light level, spectrum (color), timing and duration of exposure, and photic history (previous light exposures).”

While research still needs to be conducted about the effects of human-centric lighting on the circadian rhythms, some studies indicate that it does help.

In a 3-week light study conducted by the U.S. General Services Administration (GSA), they used tunable LED lights placed on the desktops of participants. These lights delivered saturated blue light in the morning, white light during midday, and saturated red light in the evening. The GSA states that participants reported feeling less sleepy, having more energy, and more alertness during the workday. They also felt more alert in the afternoon when they had the LED lights turned on. Additionally, participants reported falling asleep faster and waking up earlier the next day.

As LED technology continues to improve, perhaps we can soon use lighting systems that positively impact our circadian rhythms and benefit both human health and well-being.

Interested in tunable lighting controls and other options? HomElectrical carries a vast selection of tunable light bulbs and controls so you can adjust your lights the way you want.