What Human Centric Lighting Is, and Why You Need It

Human beings need natural light. Sunlight boosts vitamin D, which is critical for absorbing calcium. Natural light enhances productivity, increases energy levels and combats depression. It also directly impacts the amount of sleep you get, which, in turn, affects your overall health and well-being.

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Despite the health benefits of getting sufficient sunlight, most individuals are not able to spend their days outside. On average, Americans spend 90% of their time indoors.

Humans have evolved to live in harmony with the Earth’s daily light cycle. The way the sunlight changes from morning to night signals your body to behave a certain way. For example, sunlight makes you alert in the morning, while darkness at night makes you sleepy.

Before widespread industrialization, people worked with, rather than against, the natural light cycle. Today, most people are exposed mainly to artificial light, which is static. In many cases, artificial lighting is too dim during the day and too strong at night, which disrupts the circadian rhythm and increases the risk of disease. Humans need the right light color and intensity at the correct time of day to live life optimally.

What is Circadian Rhythm


Since most people cannot move their workspaces or bedrooms onto the lawn, they need a different way to get health-promoting light. The solution is called human centric lighting (HCL). With HCL, indoor lighting no longer revolves around unchanging fixtures. Instead, it mimics the natural world’s light cycle and supports your circadian rhythm. As a result, HCL encourages productivity during the day and relaxation at night, potentially leading to an improved overall quality of life.

Scientists have much more to learn about HCL and its health benefits. In the meantime, it’s worth exploring HCL and its impact on employees, students, patients and residents. In this guide, we’ll examine HCL, what it means, how it can help individuals get better sleep and feel more motivated and where this lighting solution can be applied. We will also explore how the Internet of Things (IoT) and smart controls play an important role in bringing HCL into homes, schools and commercial buildings.

What Is Human Centric Lighting?

What is human centric lighting?

HCL, also sometimes known as circadian lighting, refers to a lighting system that benefits human health and well-being. The ideas behind HCL focus on improving comfort, enhancing mood and boosting productivity in its users. HCL is achieved via tunable light-emitting diode (LED) fixtures, which are easy to adjust to simulate sunlight. Tunable LED lights feature various correlated color temperatures (CCTs).

What Is Correlated Color Temperature?

CCT describes how yellow or blue a white LED appears. Color temperature measurements can be traced back to 1848, when William Kelvin noted color changes as he heated a block of carbon. He first noticed a red hue that changed to yellow, which eventually reached bluish-white at its highest heat. These observations formed the basis for the Kelvin color temperature scale. CCT is expressed in Kelvin (K) temperature units.

For example, blue-whites are in the 7,000 K range, while yellows and oranges fall in the 2,000 K to 3,000 K range. A setting sun, for instance, might be assigned 2,300 K, while a cloudy sky may be 7,500 K. In the natural world, light has the lowest CCT in the early morning hours and the highest in the afternoon. Tunable LEDs can be adjusted to various shades of white to replicate the CCTs found in nature as they change throughout the day. These changing color “temperatures” impact your circadian rhythm.

What Is a Circadian Rhythm?

Circadian rhythms are the mental, behavioral and physical changes that follow a regular pattern. These changes mainly respond to the surrounding environment’s lightness or darkness. Sleeping at night when it’s dark and being awake during the day is an example of a circadian rhythm. Most living creatures, including plants, experience circadian rhythms, and this pattern repeats approximately every 24 hours. Natural light is the strongest cue needed to reset the 24-hour sleep-wake cycle.


sleeping circadian rhythm cycles

A circadian rhythm is not the same as a biological clock, but the two terms are related. Your biological clock is your innate timer, which creates your circadian rhythm. It consists of molecules that exist throughout your body and interact with your cells.

A master clock in your brain controls the biological clock in your body. The master clock consists of thousands of nerve cells that form a structure located in your hypothalamus. This structure receives input directly through your eyes. When the surrounding light goes down, the master clock tells your body to produce more melatonin, so you get sleepy. Therefore, exposure to bright light before bed can suppress the release of melatonin and keep you awake.

Improper exposure to light can disrupt the circadian rhythm and lead to an increased risk of developing sleep disorders, depression, poor eating habits and various diseases. However, if you use light to create a stable circadian rhythm, you may see an improvement in your mental and physical health.

What Are the Health Benefits of Human Centric Lighting?

Based on what we know about sunlight and how it influences our circadian rhythms and well-being, one can argue HCL restores our natural sleep-wake cycles. As a result, HCL could help individuals feel more energized during the day and more relaxed at night. However, scientists still need to determine factors, such as the required light intensity, color and exposure length necessary to benefit from HCL as one would from daylight.

Researchers must also figure out how HCL affects people differently depending on age, sex and other factors. In the meantime, consider the following studies and how they demonstrate the benefits of proper lighting:

1. Increases Productivity

How to improve productivity with lighting

If you’re wondering how to increase productivity — either in your business or home — it’s worth investigating HCL as a substitute for sunlight. Numerous studies show natural light increases productivity, satisfaction and well-being in employees. By incorporating HCL into your workspace, you can create an energizing and inspiring atmosphere, which can help your business thrive. The following studies support the potential of HCL to improve productivity levels:

  • Daylight exposure boosts mental health and improves sleep in office workers: A study published in the Journal of Clinical Sleep Medicine compared the effects of working in a windowless environment with one that received much more daylight. Those who worked in a windowless room scored lower on a self-reported health survey in vitality and mental health, and they also slept less. Individuals who worked with daylight exposure slept an average of 46 minutes more per night than those who did not work near windows.
  • Daylight with a view improves workers’ cognitive performance: According to Building and Environment article, access to sunlight and a view of the outdoors in an office improves performance, working memory and satisfaction in employees. It also reduces eyestrain. In this study, researchers used shading systems to minimize glare while allowing the sunlight to come in. The article supports the idea of utilizing carefully planned lighting, such as HCL, to improve employee comfort — and thus performance.
  • Poor lighting negatively impacts office workers: A study published in 2019 investigated the effects of poor illumination on office workers in Tanzania. The study’s participants significantly reported eyestrain, headaches and back and neck pain due to low-quality lighting, all of which could impact productivity. As a study from 2015 states, pain significantly affects productivity at work. It also makes employees less satisfied with their work environment.
  • Daylight increases alertness: A study from 2012 compared the effects of artificial light to sunlight in 29 subjects. According to its findings, subjects who were exposed to daylight in the afternoon were remarkably more alert in the early evening and performed more accurately than they did with artificial light exposure. Although HCL uses artificial light sources, it resembles natural light and may produce similar effects.
  • Cool lighting is beneficial for completing computer-related tasks: According to a study published in 2018, cool color temperatures led to significant increases in alertness when compared to warm light temperatures, regarding typing and editing tasks. Study participants also exhibited faster typing speeds and greater accuracy under cool light temperatures. Researchers believe 6,500 K is the best color temperature for office work.

Lighting Research Center states lighting strongly influences alterness

As the Lighting Research Center (LRC) states, light exposure strongly influences alertness. Dark, sleep-inducing conditions should not be replicated in the workplace with inadequate lighting. Instead, building managers should try to reproduce the bright blue sky as much as possible, either by using HCL, natural light or a combination of both.

Researchers at the LRC also conducted a study to demonstrate HCL’s efficacy in offices. As they predicted, the circadian-effective lighting led to reduced sleepiness throughout the workday, and participants reported feeling more alert and energetic during the study.

2. Improves Sleep

When your body follows the sun’s natural pattern, your sleep improves. This phenomenon allows your body to produce melatonin at the right time of day. Alternatively, if you stay up too late looking at your phone, for example, the blue light emitted from your device will simulate daylight and suppresses melatonin production, making it more challenging to get the sleep you need. Over time, lack of sleep can lead to serious health issues, including heart disease and cancer.

Under dark conditions, your brain produces the hormone melatonin, which signals your body to sleep. This process occurs a few hours before your body’s natural bedtime. Exposure to too much light delays melatonin production and sleep, which leads to poor performance during the day and the risk of developing health issues. However, it’s important to note that not all light impacts sleep. For example, warm-colored night lights will not suppress melatonin. However, a bright blue light will.

Symptoms of too much light exposure

The following studies demonstrate how exposure to light can impact sleep, for better or worse:

  • Daytime light exposure increases sleep quality: study published in Sleep Health examined the impact of circadian-effective light on office workers’ moods and sleep quality. The study found workers who received high levels of light in the morning fell asleep faster and enjoyed better sleep at night than participants exposed to low morning light levels. High doses of circadian-effective light during the day are also associated with reduced depression. Morning light resets your circadian rhythm, so you can wake up easily at the start of your day and be ready to fall asleep at night.
  • Evening light suppresses melatonin production in children: A study from 2018 investigated the effects of bright light exposure on preschoolers in the evening. By looking at the study participants’ saliva samples, researchers found melatonin production was suppressed in response to a bright light stimulus and remained at low levels for nearly an hour after they removed the light source. Parents might consider HCL to help their children get the sleep they need and promote healthy development.
  • Blue light is an alerting stimulus: In a study conducted by the LRC, participants were exposed to various blue light levels in 50-minute durations at night. After light exposure, researchers measured alertness. They found a strong correlation between blue light exposure and melatonin suppression. According to the study’s findings, the circadian system plays a vital role in nocturnal alertness.
  • Light controls when we sleep: Another LRC study asked subjects to set their alarm clocks 90 minutes earlier than their regular wake-up time. Half of them were exposed to bright light in the morning and dim light at night. The other half received the opposite — dim light in the morning and bright light at night. What the researchers found wasn’t too surprising. The first group was more awake in the morning and more tired at night than the second group, further demonstrating how light impacts sleep.

The evidence is pretty clear — exposure to bright light at night makes it more difficult to fall asleep. Lighting should be less intense and warmer at night to promote relaxation, resembling the setting sun. One of purposes of HCL is to help individuals wind down before bedtime and gradually transition into a state of sleepiness. Homeowners with HCL can also mimic the rising sun in the morning to help them wake up more easily.

3. Boosts Mood

If HCL can help you sleep better and be more productive at work, chances are, you’ll feel happier, too. HCL may also directly boost someone’s mood, particularly if they suffer from seasonal affective disorder (SAD). Roughly half a million Americans experience SAD during the winter, though the condition can occur in the summer, as well. Although women are more likely to experience SAD than men, anyone can have this condition, including children.

Causes for seasonal affective disorder

Although the exact causes of SAD are unknown, it’s believed to be affected by a lack of sunlight that occurs during the winter, which shifts the circadian cycle. SAD may also be influenced by daytime melatonin production due to a lack of daylight, which can lead to sleepiness in the afternoon. Lastly, when some individuals miss out on sunlight, they might experience decreased serotonin levels in the brain, leading to SAD and depression.

People with SAD experience symptoms such as a greater need for sleep, anxiety, sadness, irritability and a lack of energy. Many of these side effects overlap with standard forms of depression — including loss of interest in daily activities and changes in appetite. Though it typically responds well to common treatments for depression, like antidepressants and therapy, doctors can remedy it with other methods. One way to treat SAD is with light therapy.

Light therapy has existed since the early 20th century to treat various conditions, from sleep disorders to infections. Today, individuals use light boxes to replace sunlight and ease SAD symptoms. Light boxes create a bright white light that tricks the brain into thinking it’s being exposed to sunlight. Doctors recommend getting this dose of “sunlight” in the morning, or before 10 a.m., and for at least 30 minutes a day.

Considering what we know about sunlight, SAD and light therapy, it may be safe to assume HCL can be part of a mood-boosting environment. Whether used at home, in the office or both, HCL may help individuals feel happier and more energetic all year long.


Benefits of human centric lighting

The Benefits of Human Centric Lighting and IoT

Imagine working in a windowless office all day. When you start work, the lights in your cubicle are bright as a cloudless sky. As the day progresses, the lights gradually, and automatically, get dimmer and change from an energizing bluish-white to a warm, amber glow. On your ride home, you notice how the lighting in your personal workspace matches the world outside, and you feel yourself becoming more relaxed and ready to enjoy some downtime.

Even though your co-workers prefer working in brightly lit cubicles all day, you find your setup works better for you. All of this, plus the customization, is possible with HCL and IoT.

IoT allows you to control the lighting system in your entire home, office or individual space by using an app on your phone or another device. Your IoT device communicates with the connected LED fixtures and tells them to change color and intensity to match your desired effect.

For example, if you’re just waking up and want to feel alert as you make coffee, you can control LEDs with your phone and tune them precisely to the color temperature and intensity you want, which, in this example, might be a bright stimulating white. Before bedtime, you can adjust your bedroom’s lighting to look like candlelight or gradually fade like the setting sun.

If you wish, you can set the lighting to change automatically, according to a certain schedule. For example, maybe you want the lights in your kitchen to be brilliant and inspiring at noon when you’re ready to make lunch. Or perhaps you want your home to resemble a movie theater when you arrive at 6 p.m. every day. A smart home will sense when you walk through the door and automatically turn your living room into a dimly lit cinematic palace.

Another possible option is to synchronize the lighting system with nature, so the inside light always matches the outside environment — you don’t even have to think twice about it. If you need to change the lighting momentarily, you could still do so manually with IoT. You can find settings that work for your needs and lifestyle.

LED fixtures are perfect for HCL and IoT because they are precise and easily adjusted. LEDs are also favored for longevity, efficiency and flexibility, making them easy to incorporate into an HCL system at work or home. LEDs can be controlled by IoT devices with outdoor fixtures, as well.

Overall, when you combine the ideas of HCL with smart technology, you face endless options regarding customization and lighting solutions that fit your needs. You can truly create a home or workspace that uses lighting to support your circadian rhythm and daily activities, and it can all be automatic. Anyone who is concerned with improving their well-being should consider the potential of HCL and IoT.

Where to Use Human Centric Lighting

When to use human centric lighting

Similar to sunlight, HCL can make any environment more comfortable and suitable for the tasks at hand. For example, schools, health care facilities, employers and homeowners are currently experimenting with HCL and how it impacts productivity, comfort levels and health. Let’s explore the various settings and how the people in these environments might benefit from HCL. As you’ll see, in many cases, HCL simply makes sense.

1. Health Care Facilities

HCL may play a vital role in health care because it can potentially help patients heal more quickly by supporting their circadian rhythms and assisting their sleep. HCL may also improve patients’ moods and help them fight depression.

A report published in 2018 discusses data regarding the impact of daylight on patients. The data, which had been collected over 15 years, shows that patients who had beds near windows experienced shorter hospital stays than those with beds near doors. This phenomenon suggests that HCL, when mimicking daylight, may help all patients heal faster — not just those with window-side beds.

Another study, published in the Journal of Sleep Research, examines lighting impact on cardiology ward patients and how it affects sleep and mood. In the study, some patients occupied rooms with standard lighting, while others stayed in rooms with dynamic 24-hour light systems. The dynamic spaces exposed patients to low light at night and two hours of bright light during the day.

Patients in the dynamic rooms slept better and longer than those in the standard areas. This study suggests HCL could help patients sleep and heal more quickly.

Benefits of personal human centric lighting

HCL may be especially helpful in assisted living facilities where residents spend a substantial amount of time indoors and are less likely to experience the light-dark cycles they need to support their circadian rhythms. With personal HCL systems, residents may enjoy improved mental health and enhanced well-being.

HCL can also serve individuals with Alzheimer’s disease. People with Alzheimer’s disease often experience depression and sleep disturbances along with memory loss, all of which reduce their quality of life. Researchers have shown that customized LED solutions positively impact sleep and mood in individuals with Alzheimer’s disease living in long-term care facilities.

Lastly, HCL might benefit health care staff by providing a stimulating environment to keep them alert. Light can be a better alternative to coffee since its effects do not last as long as caffeine. This factor means health care workers can feel energized at work but still be able to rest when their shift is over. A study published in 2013 compared caffeine’s effects with blue light regarding alertness in humans. The researchers found that both enhance accuracy, but blue light outperformed caffeine when a distraction was present.

HCL is also used to help health care employees feel more comfortable at work because they regularly face high-stress situations. Additionally, staff members require proper lighting to do their jobs well. According to the Journal of Environmental and Public Health, inadequate lighting conditions impact staff performance and cause headaches and eye fatigue. However, when lighting improves, so does job performance.

2. Schools

It can be difficult for kids to wake up early and feel motivated to get to school on time. It’s even more challenging to sit in a poorly lit classroom all day and learn. Most schools lack access to natural light, and many students spend their days under fluorescent lamps. Although fluorescent lighting has been the standard for a long time, studies have found it has negative effects on humans. Therefore, it may be time to replace fluorescent lighting with LED fixtures and bring HCL to schools.

HCL can potentially help students transition out of sleepiness, feel more awake and have an easier time learning. According to some studies, cool blue light, in particular, can help students perform academically. Consider a study published in Optics Express. In this study, researchers explored the effects of CCTs on elementary school students to determine the potential of dynamic lighting.

According to their findings, light set at 6,500 K positively affects academic performance, and light set at 3,500 K encourages recess activities. This evidence supports the idea that cool light is stimulating, and warm light is relaxing.

A second study from 2014 explored the effects of blue-white light on high school students and their academic performance. According to this study, students who spent time in a room with blue-white illumination demonstrated faster cognitive processing speeds and improved concentration compared to those in a space with standard lighting. Both of these studies show how HCL can promote learning and positivity in schools.

HCL may prove valuable for teachers as well, who can use the lighting as a behavioral cue and teaching tool. With intuitive controls in place, teachers can energize students with cool blue lights that mimic sunlight and help them calm down with warm color temperatures.

3. Commercial Buildings

HCL has a lot of potential in offices, factories and other commercial settings. By creating an environment that replicates nature, employees can enjoy more comfortable workspaces that promote concentration, focus and motivation. If workers can control the lighting in their individual workspaces, they may also enjoy greater satisfaction. Anyone who feels happier at work is likely to experience a boost in productivity, regardless if they clock in at an office or warehouse. Happy employees also make more supportive co-workers, which can ultimately help a company thrive.


Benefits of human centric lighting for night shift workers

HCL might be particularly helpful to night-shift workers, making a positive impact on their performance, comfort levels and job satisfaction. Companies might use LEDs to help employees adjust to working while it’s dark outside, thus improving production levels and accuracy. For example, in a study provided by the International Labour Organization, better lighting led to a 10% increase in productivity and a 30% decrease in errors in some factories.

Appropriate lighting can also combat fatigue associated with repetitive tasks. Overall, HCL can be another element of creating an inspiring, comfortable workplace for employees in all industries.

4. Homes

Americans are spending more time at home than ever before. At home, people can shop, be entertained, work out, socialize and much more, thanks to technology. People can also make their homes more inviting and satisfying with the right lighting. While indoor lighting shouldn’t wholly replace time spent outdoors in the sunlight, it can be a great option for promoting health and happiness for all those moments spent inside.

how to use human centric lighting in the home

HCL can serve several purposes in a home. People might use it to gradually fill a bedroom with “sunlight” and help them wake up more naturally. At night, HCL can mimic the sunset and slowly fade to darkness to help homeowners fall asleep. This effect may help individuals coping with sleep disorders — which consists of an estimated 50 to 70 million Americans — get the rest and rejuvenation they need to lead healthy, productive lives.

HCL can also help homeowners complete tasks in the kitchen or get ready for work in the bathroom with stimulating color temperatures. Individuals can adjust it to set a particular mood or increase aesthetic appeal throughout the home.

Homeowners have exciting, flexible options when it comes to lighting fixtures, too, allowing them to beautify their living spaces as they implement HCL. For example, they might choose innovative recessed lighting, color-changing LED tape or under-cabinet task lights to bring HCL into their houses in unique ways. Attractive pendants and wall sconces allow homeowners to embrace HCL while also adding visual appeal to their rooms.

Individuals have various outdoor lighting options as well, which can increase security and curb appeal with attractive and intuitive light sources. There’s virtually no limit to the kinds of indoor and outdoor lighting solutions homeowners can choose to liven up their abodes and boost their well-being.

Regardless of someone’s decorating style, HCL allows individuals to easily control the comfort, usability and desirability of their living spaces. HCL is tailored to each person and changes as the user’s needs and wants change. No matter the time of day, users can adjust the light settings to suit their preferred brightness levels and color temperatures. With HCL, the home environment is no longer a stagnant indoor space. Instead, it becomes a dynamic setting that brims with life.

Should I Buy a Human Centric Light Fixture?

Although there’s still much to learn about light and how it impacts human health and well-being, many experts would agree the future is bright with HCL. This lighting solution is undoubtedly one worth exploring. With most people spending a majority of their days indoors, they must find a way to get the light they need at the right time of day. Based on what researchers know so far, HCL seems to be an effective alternative to natural light.

With this knowledge, it’s impossible to ignore the potential of HCL and IoT and how we can use light technology to improve our lives at work and home both effortlessly and automatically. While scientists continue conducting research, architects, interior designers, contractors and other professionals should consider using HCL as a new way to approach lighting. Clients will likely appreciate HCL’s many benefits.

At WAC Lighting, we are proud to provide our clients with cutting-edge technology and automated HCL solutions using long-lasting integrated LED fixtures. We offer affordable, customized lighting products for both commercial and residential applications. If you would like to learn more about human centric lighting and how we can help you achieve your business goals, please reach out to us today.

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