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Lumens and Lux: What You Need to Know

Multiple hanging ceiling lights

Light bulb shopping used to be relatively easy. Traditionally, we would replace our light bulbs based on wattage. As governments began phasing out the use of incandescent bulbs, replacing them (with CFL, halogen, or LED bulbs) has become trickier for consumers. Rather than relying on wattage — the amount of energy needed to power a light bulb — manufacturers are now labeling their products based on other outputs. The most important specs for understanding the effectiveness of light bulbs are lumens, lux, and color temperature.

What Are Lumens and Lux?

When purchasing light bulbs, it is nice to know exactly how much light they will emit. This can be indicated in terms of lumen or lux — both of which are related to brightness, but they measure slightly different things. Simply put, a lumen is the measure of brightness from a given light source (no matter what direction the light is).  You’re probably familiar with the light output that a 60W incandescent bulb offers, for example. This wattage is not comparable to that of the LEDs that you’d find on the shelves today. In other words, we can no longer rely on solely comparing wattages to determine efficiency. Today, the higher the lumen measure, the brighter the bulb. Watts, on the other hand, measures the energy used.graphs showing which bulbs are being phased out

Lux also measures illuminance; however, it accounts for the total amount of light that falls on a given surface.

1 lux = 1 lumen × (square meters) or lx = lm × m2

A flux of 1000 lumens, for example, concentrated into an area of one square meter, lights up that square meter with an illuminance of 1,000 lux. At 10 square meters, the output is 100 lux. LUMENS vs LUX light

Measuring lux is important because it reveals how many lumens you need to illuminate any given area. Keep this in mind if you need to illuminate larger areas in your home – the larger the area, the more lumens you need, which can generally be increased by adding additional lighting fixtures. Conversely, smaller spaces require fewer lumens for proper illumination.

Lumen, Lux, and Your Circadian Rhythm

Remember that your body is biologically programmed to receive different types of light exposure throughout the day (and night).  The quality and quantity of your light exposure is essential for keeping your natural circadian rhythm (or sleep/wake cycle) on track. Below is a chart that outlines standard light exposure (in lux) while outdoors:

When choosing light bulbs for your home or office, be mindful of their light output (rather than just wattage). Ideally, you want to use bulbs that mimic natural sunlight during sunrise, midday, and after sunset. Proper lighting will help you maintain your energy and mood during the daytime, and promote deeper, better sleep at night.

Please note that color temperature is the third factor in the lighting trinity. For continued reading, be sure to check out Kelvin Color Temperature: What You Need to Know

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How to Leverage Light Color to Support Your Circadian Rhythm

Ketra Precision Optics

Article at a Glance:

  • Color is the appearance of an object with respect to the wavelengths of light that are reflected off of it.
  • Research shows that light is one of the most influential inputs to your circadian rhythm.
  • The natural phases of sunlight are naturally programmed into our biology.
  • Ideally, you want to incorporate “circadian” lighting in your home or office that mimics the color temperature of the sun’s natural light as it progresses throughout the day.

Kelvin Color Temperature: What You Need to Know

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Lighting—it’s all about color temperature, lumens, and lux.  Why? Because these measures of light not only affect the atmosphere of a room; they can also impact a person’s energy level, mental clarity, and well-being while inhabiting that space.

What Is Color Temperature?

This refers to the “warmth” or “coolness” of a light source, measured in Kelvins (K). This measurement is based on an absolute scale, which means that it starts at zero and continues to increase.

Lower temperature bulbs (1,000–3,000K) produce warm, soft white light — like that of candlelight, ambient sunsets, or standard incandescent bulbs.

Medium temperature bulbs (3200–4500K) produce neutral white light that creates a bright and inviting ambiance.

Higher temperature bulbs (5000–10,000K) produce cool white light.  Color temperatures in this range are closest to the appearance of daylight. This range of light is often described as “clinical” because it makes objects appear crisp and vibrant.

In short, the higher the Kelvin rating (expressed in K), the whiter the light will appear. For a more in-depth look at light sources and color temperature, reference the chart below:

Color Temperature chart

How to Interpret Kelvin Color Temperature Vs. Colors

While kelvin follows an absolute scale, human vision can perceive many colors that exist outside of this spectrum. Color is the appearance of an object with respect to the wavelengths of light that are reflected off of it. This attribute is determined visually by the hue, saturation, and brightness of the light reflected off of an object.  With that said, it’s common practice for businesses to use the CIE 1931 color spaces to identify specific colors. Rather than describing how colors appear to humans, this Color Matching System helps users numerically specify a measured color and accurately reproduce it (e.g. in print or illuminated displays).

Color temperature scale

There is no true conversion of nanometers to kelvin. However, within the CIE color spaces shown above, you can also see the Kelvin scale (the curved black line in the center of the spectrum).  Modern lighting technology will often produce vibrant colors which are way off the Kelvin line.  Note that any light that does not fall on this line can be classified as a (numerical) color but not a Kelvin.

Color Temperature and Your Circadian Rhythm

Research shows that light is one of the most influential inputs to your circadian rhythm. It enters the eyes through special receptors that are especially sensitive to blue light, which provides humans with precise blueprints for carrying out important biological functions over the course of 24 hours (e.g. waking up, eating, exercising, and sleeping).  So, when it comes to regulating your sleep/wake cycle, the saying, ”timing is everything” should really also acknowledge color temperature. clock showing circadian rhythm

Now think about a typical 24-hour period. As the sun gradually changes its position in the sky, the light color temperature transforms from warm to cool, and back to warm again.  These natural phases of sunlight are naturally programmed into our biology, so when choosing lighting, be sure to consider the light sources that support your mood, energy, and natural sleep/wake cycle.

Ideally, you want to incorporate “circadian” lighting in your home or office that mimics the color temperature of the sun’s natural light as it progresses throughout the day. For example, higher temperature bulbs are ideal for midday use because they help stimulate alertness and may assist with maintaining your energy and focus. So, while you’re working on specific tasks, it makes sense to use vibrant, invigorating light.  Lower temperature bulbs are conducive for illuminating spaces after sunset, especially if you want to create a more romantic setting or prepare your body to fall and stay asleep. In short, cool bright lights promote wakefulness and warmer lights encourage restfulness.

For continued reading, be sure to check out Lumens and Lux: What You Need to Know

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What Is Junk Light and Why is it Bad for You?

Light bulb in junk light

Article at a Glance: 

  • Junk light is a common occurrence found in artificial light sources like LEDs and fluorescents. 
  • Junk light specifically refers to blue, green, and violet light. 
  • We didn’t always have junk light, our ancestors used to solely rely on natural sunlight and fire. 
  • Technological advances in lighting led to incandescent, halogen, fluorescent, and LED bulbs. Greater access to lighting has resulted in an “always-on” culture and overexposure to certain wavelengths. 
  • Artificial blue light during the daytime can zap your energy and negatively affect how you feel and function. 
  • Too much artificial blue, green, and violet light at night can suppress your body’s ability to produce the melatonin you need to fall and stay asleep. 

“Junk light” refers to specific wavelengths of [visible] light that artificial light sources — such as LEDs and compact fluorescents (CFLs) — emit.  These light sources lack many of the sun’s frequencies that our bodies and brains need, and yet, they amplify the amount of junk light they emit beyond what humans have evolved to handle.

The wavelength ranges that cause the most concern include the following: 

green light (492-577nm)

blue light (455-492nm)

violet light (400-455nm)

graph showing viable light spectrum
Source: Arch Lighting

Dave Asprey, the Father of Biohacking, coined the term junk light to emphasize the negative impacts that overexposure to blue, green, and violet wavelengths can have on a person’s health and performance. He says, “Junk light is worse than junk food; it’s the high fructose corn syrup of lighting.” In other words, exposing yourself to artificial junk light rather than natural sunlight or incandescent light, which is much warmer than the light found in LEDs and fluorescents, is akin to consuming a spoonful of sugar versus a nutritious meal.

The reason why junk light is arguably worse than junk food is that it has become so ingrained in our everyday lives. In fact, studies show that the average American spends more than 92% of his or her time indoors under artificial lighting.  People are also getting more screen time than ever before, which means even more exposure to junk light via LED screens. Overexposure to artificial junk light, in turn, negatively impacts your energy, mood, and performance.

How Does Junk Light Affect Your Health During the Daytime? 

Inside our eyes are a class of light-sensitive eye cells, called ‘intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells absorb light — especially blue light — in order to properly set our circadian rhythm in accordance with the rise and fall of the sun. That’s why when sunlight shines through your window each morning, your body temperature naturally starts to rise, and you begin to feel more alert. Conversely, when the sun goes down, the human body should naturally start to decrease in temperature and prepare to sleep.

With that said, we are no longer solely relying on sunlight and fire like our ancestors. Numerous technological advances in lighting have led us to the world we now live in, where the lights are always on and our bodies don’t really know what time it is anymore.

Think about it. The sun naturally changes its position in the sky throughout the day until it descends below the horizon at nighttime.  If you were outside during the day, your body would be exposed to different temperatures of light depending on where the sun was located at any given time.  However, since most people spend more time indoors than outdoors, we are now getting more exposure to artificial lighting than natural sunlight.

graph showing wavelength of Sunlight, LED, incandescent and CFL blubs
Source: Calories Proper

Note that there is an inverse relationship between the wavelength of light (measured in nm) and the amount of energy that specific wavelengths contain. Light rays with longer wavelengths contain less energy, and those with shorter wavelengths have more energy. LEDs and fluorescents are notorious for emitting high levels of blue light (short wavelengths).

Overexposure to blue light can have several negative impacts on your health and performance during the daytime, such as:

  • Lack of energy
  • Digital eye strain
  • Difficulty focusing
  • Decrease in productivity
  • Circadian rhythm disruption
  • Greater risk of getting macular degeneration (the leading cause of blindness) over time

Unfortunately, most office buildings (where people spend 8-10 hours a day) are flooded with LEDs and/or fluorescents. Our gyms, grocery stores, airports, and malls all use artificial light sources too. They look great for commercial purposes — and may even trick us into buying more! — but junk light does our health zero justice.

How Does Junk Light Affect Your Sleep at Night?

Each night as the sun goes down, your body should naturally start producing more melatonin, which is the key hormone that your body needs in order to fall and stay asleep.  It also plays an important role in countering infection, inflammation, cancer, and auto-immunity (NCBI).  Of course, it’s much more difficult for your body to produce this hormone if the lights are still on, or if you’re constantly glaring at screens leading up to bedtime.  Many studies have shown that blue light suppresses melatonin production, which makes sense since wavelengths in this range promote alertness.

Research has also suggested that green and violet wavelengths of light could potentially delay or disrupt your sleep, especially if they are used in the hours leading up to bedtime.

When you don’t get consistent, quality sleep at night, you’re at greater risk for many health issues, including but not limited to:

According to Matthew Walker, Neuroscientist and sleep researcher, “After just one night of only four or five hours’ sleep, your natural killer cells—the ones that attack the cancer cells that appear in your body every day—drop by 70%.”  Aside from putting your long-term health at greater risk, you’re also basically setting yourself up for failure tomorrow because you won’t be showing up as energetic, positive, or productive as you otherwise would have if you had gotten a full 7-9 hours of sleep the night before. This “sleep debt” can very quickly turn into a vicious cycle of feeling fatigued during the day and “wired and tired” at nighttime.

How to Stop Junk Light

Un-training your brain to turn the lights down or off may seem daunting, but it doesn’t have to be.  Here are some tips on how to prevent overexposure to junk light and protect your circadian rhythm:

  • Maintain a routine schedule in which you wake up and go to bed at the same time every day.
  • Get at least 20-30 minutes of natural sunlight every day (NCBI).
  • Wear blue light blocking glasses during the daytime that block up to 75% of blue light*
  • Wear junk light-blocking glasses that are specifically designed to help you hack your sleep; they should block up to 100% of blue, green, and violet wavelengths of light to help put your brain into an alpha (or meditative) state before bedtime.
  • Use blackout curtains in your bedroom.
  • Keep the lights dim in your house in the hours leading up to bedtime.
  • Use Junk Light Dots (stickers) to cover up those pesky little power source lights that you often find on computer or tv monitors, or on appliances.
  • Makes sure that you make room for 7-9 full hours of sleep every night.

*You don’t want to wear glasses that block more than 75% of blue light during the daytime because your body still needs SOME blue light in order to remain active and alert.

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

Open work space

Article at a Glance: 

  • Light directly impacts our visual and non-visual responses.
  • When we don’t get enough exposure to the sky-blue region during the day, and/or if we get too much exposure to wavelengths in this region at nighttime, we are at risk of experiencing circadian rhythm disruption.
  • Poor lighting can negatively impact mood, energy, focus, and productivity during the daytime. It can also affect your sleep later at night.
  • Circadian lighting is a healthy alternative to conventional LEDs and fluorescent light sources.
  • There are three ways to implement a circadian lighting system including intensity tuning, color tuning, and stimulus tuning.

Light is the most powerful synchronizer for the human body clock, as it affects both our visual and non-visual systems. And while this clock is deeply engrained in our biology, many experts argue that more time indoors under artificial light and in front of digital screens can throw this natural rhythm off-center.  Research indicates that circadian rhythm disruption is associated with a wide variety of adverse health consequences, including but not limited to increased risk for premature death, cancer, metabolic syndrome, cardiovascular dysfunction, immune dysregulation, reproductive problems, mood disorders, and learning deficits. (1)  Circadian light is a healthy alternative to conventional lighting that offers a real solution for improving mood, performance, and well-being.

What is “circadian light”?

The concept of circadian light stems from the human body’s natural body clock, aka your circadian rhythm, which operates on approximate 24-hour cycles.  Unlike conventional junk light – artificial light from LEDs and fluorescents — circadian lighting is scientifically designed to emit specific wavelengths that help regulate your circadian rhythm. This technology is sometimes also referred to as Human Centric Lighting (HCL) or wellness lighting.

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 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 a 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.

Which circadian light system is the most effective?

Truly circadian light systems infuse the sky-blue region of light (near 490nm) to pinpoint key photoreceptors that regulate your mind and body. They essentially mimic the circadian benefits that you would otherwise get from natural sunlight if you were outdoors.  So, in choosing circadian lighting for your home, office, or other building, make sure that the bulbs specifically emit sky-blue light during the daytime. If they have a nighttime setting or dimming capability, you want bulbs that completely remove all blue light to prompt nighttime signals and prepare your body for sleep.

Why is circadian lighting important?

Studies show that insufficient or inappropriate light exposure can disrupt the body’s biological rhythms which can have adverse consequences for performance, safety, and health. (3) Remember, not all blue light is bad; critical sky-blue light helps entrain your circadian rhythm, boost energy and improve mood during the daytime. At night, keeping your bedroom dark is essential for preparing your body for sleep.  Circadian lighting can help us maintain these natural oscillations between light and dark while also allowing us to live in harmony with modern technology.

What applications can circadian lighting be used in?

Circadian lighting can be used virtually anywhere, but it may be most effective for the following applications:

  • In your home
  • Office buildings
  • Hospitals
  • Restaurants
  • Nursing Homes
  • Gyms
  • Malls


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Why Light-Based Technology is Important for Connectivity, Health and More

Fiber Optic Cable, Wind Turbine, Drone,

Article at a Glance: 

  • As the world learns to navigate social distancing protocols, the demand for greater access to the Internet, information, and curriculums has grown exponentially.
  • Public health concerns around the COVID-19 coronavirus have also driven the need for more precise medical equipment.
  • Light science and light-based technology have become incredibly important in aiding a host of global issues, such as telecommunications and connectivity, better medical treatments, sustainable farming, and clean energy.
  • International Day of Light is an annual event that takes place on May 16th to honor the role that light plays across different sectors and fields, and how it positively impacts communities around the globe.

While people across the globe are spending more time at home, connectivity to others and access to information is more important than ever. Light science and light-based technology are notably at the forefront of making remote work, online schooling, and more effective healthcare possible.  Optics and Photonics may also be the innovative technology that farmers need in order to develop sustainable farming practices.

Photo Source: UNESCO

Light-Based Technology, Telecommunications, and Connectivity

Humans have a primal need to connect and communicate with one another – almost as strong as our need for food and water. Even now, while we weather the coronavirus pandemic, we see people standing on their balconies waving and singing to their neighbors.  Beyond windows and balconies, light-based fiber-optic cable technology makes social connection possible at incredibly high speeds.

Optical fiber network cables essentially use glass fibers to transmit light and huge volumes of data all over the world.  The very first optic fiber cable traveled 3,148 miles across the bottom of the Atlantic Ocean and was capable of handling 40,000 telephone calls simultaneously. (1)  Today, optic fiber telecommunication technology supports the world’s long-distance phone calls and social media activity.

High-speed connections and light-based technologies are more important than ever right now because education programs are going virtual for the foreseeable future.  In order to make the most of remote learning, students need the proper communication infrastructure and digital devices (e.g. computers and laptops) to access educational resources from home.  Lighting fixtures can also create an effective learning space for students that need to read or study at nighttime. Learn more.

Photo Source: UNESCO

Light-Based Technology, Better Diagnostics, and Medical Treatments

Researchers worldwide are frantically working on developing better diagnostic measures for those affected by COVID-19.  Fortunately, light-based optical and photonic technologies have joined the fight against SARS-CoV-2, the virus causing this disease.

You can think of optics as a branch of physics and photonics as a branch of engineering. Together, these technologies involve generating, detecting, and manipulating light to make possible:

  • rapid preliminary screening of potentially infected individuals
  • more accurate molecular diagnosis
  • reliable monitoring of disease progression
  • disinfection of contaminated surfaces (2)

Examples of optic and photonic technologies include high-quantum-efficiency multispectral cameras, visible-light laser diodes and LEDs, infrared bolometer arrays, narrowband optical filters, and wideband multispectral optical spectrometers. (3)  These technologies are now on the frontlines with doctors, nurses, and researchers playing a life-saving role all over the world in the battle against SARS-CoV-2. Learn more.

Photo Source: UNESCO

Light-Based Technology, Sustainable Farming, and Clean Energy

The current COVID-19 crisis has caused many businesses (e.g. restaurants, hotels, and airports) to stop operating.  This has subsequently led to large production cuts from farmers and distributors and major disruptions to food-supply chains.  The World Food Programme (WFP), the food-assistance branch of the United Nations, has expressed the potential for a “hunger pandemic”, saying that it could be “the worst humanitarian crisis since World War II.”  Given the concerns over commercial trading across borders amidst COVID-19, there is an even greater need for sustainable farming that uses natural resources more efficiently with less food waste and a reduced environmental footprint.  That’s where light-based technologies come in.

Optic and photonic technologies are becoming more popular for efficient, sustainable agriculture and clean energy. Indoor farms can now use sensors to measure plant growth and improve the cultivation of crops and livestock. Farmers can also use drones with imaging sensors to scan for signs of drought, pests, and disease. These light-based technologies are contributing to what is now known as “precision agriculture” because they help increase crop yields while also minimizing the use of resources like land, water, and fertilizer.  As we continue to navigate the economic influxes associated with the COVID-19 pandemic, it will be imperative for farmers to utilize light-based technologies for efficient, sustainable, and clean agricultural practices. Learn more.

Honoring the History of Light-Based Technology

On May 16, 2020, UNESCO will host the 3rd annual International Day of Light — a global initiative that recognizes the important role light plays in science, culture and art, education, sustainable development, and diverse fields such as medicine, communications, and energy. (3)  

May 16th is a significant date because it is the anniversary of the first successful operation of the laser in 1960 by physicist and engineer, Theodore Maiman. Today, lasers are everywhere — in research labs, medical clinics, supermarkets, just to name a few places. They are also used regularly for manufacturing automobiles and plastics.  The invention of the laser is a perfect example of how a single scientific discovery can positively impact society beyond its original scope in healthcare, engineering, communications, and many other diverse fields.

Despite the current global challenges that we are facing, light-based technology is providing efficient and affordable solutions across many different sectors.  Light science is without a doubt impacting virtually all areas of our lives, and that’s why we’ll hope you’ll celebrate International Day of Light with us.

For continued reading, click here for additional articles about leveraging healthier light for healthier living.


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Proper Lighting Can Improve the Quality of Your Sleep

Sleeping woman on bed

Article at a Glance: 

  • Humans have long relied on the sun’s energy as well as fire and candlelight for illumination; however, we now have other technologies that allow us to stay up later into the evenings. 
  • Modern technology has led to fluorescents, LEDs, and an ever-growing array of digital devices with LED screens. 
  • More time indoors means more time exposed to artificial lighting, which directly impacts circadian rhythms and sleep patterns. 
  • The human body needs warmer (redder) lighting in the hours leading up to bedtime as the wavelengths in the red light spectrum are closest to the wavelengths emitted by the sun during sunset.
  • In contrast to short blue light wavelengths that suppress melatonin production, warm red light is better suited specifically for evening hours because it helps the body produce more melatonin (the sleep hormone).

Centuries ago, our ancestors relied solely upon the sun and fire to illuminate the space around them. This was conducive was regulating their circadian rhythms naturally. Conversely, modern technology has pushed society indoors, which means more exposure to junk light and chronic sleep problems.  Too much light, especially at night time, prevents your body from producing melatonin naturally, which, in turn, makes it more difficult to fall and stay asleep. Redder (warmer) lighting is more appropriate to use in the hours leading up to bedtime because it is closer to the natural light spectra at dusk. This lighting promoted better, deeper sleep.

How Light Influences Your Sleep

Your body perceives light and darkness through the eyes, which contain blue-light-sensitive cells called intrinsically photosensitive retinal ganglion cells, or ipRGCs. These cells are directly responsible for communicating how bright it is in the environment to the brain’s master clock. So, it’s no coincidence that humans systematically rest at night when it is dark outside.  As the sun descends below the horizon each evening, the color temperature of the sky changes accordingly, and your body begins to produce melatonin – the key ingredient (hormone) for falling and staying asleep. Resting in a cave-like environment (like our ancestors used to) is essential for helping the body wind down and recover overnight.

How the Lighting Revolution Has Affected the Way We Sleep

For many centuries, humans relied on candlelight at night. Then came the development of incandescent bulbs. These light sources emit “warmer” light (reddish in color), which is conducive to illuminating the space at night around you without affecting your sleep.

Today, we not only have new advances in lighting technology (thanks to fluorescent and LED bulbs), but we also have greater exposure to it. In fact, many people — labeled as the “Indoor Generation” — spend as much as 90% of their time indoors under artificial lighting and/or using digital devices with LED screens. These light sources emit “cooler” light (bluer in color) that mimics daylight when the sun is at its highest point in the sky.  Given that blue light promotes alertness, exposure to blue wavelengths at night is not ideal.

See the chart below which shows the spectrums of different light sources: graph showing Light Source spectra

Light and Sleep: The Bottom Line

“Lights out!” at night isn’t just a pastime; it is necessary for regulating your circadian rhythm and hormones.  In a world where the lights are always on, it’s important to be mindful of their color temperature and brightness, especially in the hours leading up to bedtime. With that said, red light is an appropriate option for those that need to get up in the middle of the night.

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LEDs: Are They Really Better for the Environment?

Lightbulb sitting in leaf

Article at a Glance: 

  • Lighting has seen a profound evolution from fire to incandescent, halogens, compact fluorescents, and now LED technology.
  • The light bulb plays an integral part in how humans and the world live every day.
  • There are very clear benefits of using LED light bulbs; however, there is also evidence that the abundance of bright LEDs, especially at nighttime, can have dramatic ripple effects on wildlife and the ecosystems that plants and animals inhabit.
  • To protect the Earth, it’s important to find a healthy balance between using energy-efficient LED lights and knowing when to turn them off.

“The rapid adoption of LEDs in lighting marks one of the fastest technology shifts in human history.” – Goldman Sachs(1) 

The humble light bulb is arguably one of the most transformative inventions since man-made fire.  Throughout its history, it has undergone several technological advances to make it more energy and cost-efficient.  The biggest shift in adoption has notably taken place over the past decade as more people have begun trading traditional incandescent bulbs for LEDs. Proponents of this trend point out that LED light bulbs save consumers money and are eco-friendly, but the truth is that this issue isn’t so black and white. While LEDs effectively power the world’s homes and cities, they also contribute to light pollution that disrupts wildlife and the ecosystems that they inhabit.

What are the Pros of Using LEDs?

Compared to their incandescent and fluorescent counterparts, LEDs are long-lasting, reliable, and flexible. Key differences include the following:

  • LEDs typically use 25%-80% less energy than traditional incandescent bulbs and can last 3-25 times longer. So, it could be said that LEDs actually help you lower your carbon footprint. (2
  • LEDs emit much cooler light and less heat than incandescent bulbs. This makes them somewhat safer because there’s a lower risk of combustion.
  • Given their long lifespan, LEDs don’t need to be replaced as often and are considered lower maintenance than other bulbs.
  • LED lights can be used in many applications, such as street and road lighting, industrial lighting, security lighting, as well as residential and commercial lighting.
  • The rapid development of LED technology leads to more products and improved manufacturing efficiency, which also results in lower prices. (3

For all of these reasons, LEDs are projected to comprise 69% of the global market by 2020, up from 9% market penetration in 2011. (4

What are the Cons of Using LEDs?

Despite how cost and energy-efficient LED lights are, there are considerable drawbacks to note about these bulbs, including:

  • LEDs emit short blue wavelengths of light, also known as junk light. The concentration of blue light found in these bulbs is actually much higher than what the human body is naturally built to handle.
  • Similar to how overexposure to junk light can lead to circadian rhythm disruption in humans, the excess light we dump into our environments is endangering ecosystems by harming animals whose life cycles depend on oscillations between light and darkness. (5)
Document explaining how LED lighting interacts with wildlife
Source: International Dark-Sky Association

Tips on How to Leverage the Benefits of LEDs and Protect the Environment

In today’s “always-on” culture, we typically don’t think twice about flicking a switch to illuminate our space, but perhaps we should.  Here are a couple of tips to live in harmony with technology and wildlife:

  • Save your cooler LED bulbs for inside your home and opt to use warmer incandescent bulbs for outdoor lighting so that you don’t disturb the natural biological functions of the insects and animals nearby.
  • You can also use red LED bulbs that specifically emit warm red light rather than cool blue light.
  • Be mindful about keeping your lights on after the sun goes down in the evenings. Consider investing in dimmers and/or turning lights off completely if you aren’t using utilizing them.


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How to be More Compassionate with Your Lighting

4 people next to campfire at night

Article at a Glance: 

  • Humans once solely relied on sunlight to illuminate their surroundings. Natural light/dark cycles helped entrain biological rhythms.
  • The history of light, from the discovery of fire to modern LEDs, has transformed the way people live by essentially giving us more time each day for different activities.
  • Despite the many benefits of the lighting evolution, it’s important to acknowledge that the light bulb may have a dark side: it has stolen the night sky and negatively impacted the biological rhythms of humans and biodiversity.
  • Warmer (redder) lighting is more conducive and compassionate for nighttime use because it won’t throw off circadian rhythms.

Artificial light has become an integral part of everyday life for people all over the world. The spread of electricity has literally transformed how we communicate, travel, work, and much more — even at nighttime. As a result, society has shifted away from the natural cycles between light and dark that our ancestors once lived by. (1Keeping the lights on not only impacts human health, but studies show that this can also have sizable environmental consequences. Excessive blue-rich illumination from LEDs and fluorescents disrupts the natural rhythms of humans and biodiversity created by millions of years of the earth’s steady axial rotation. (2Alternatively, warmer colored light bulbs – especially at night – are more appropriate and compassionate outdoor lighting options for humans and the environment.

How Lighting Has Changed Over Time

Our earliest ancestors lived in a world where, when the sun went down, almost everyone lived in the dark.  It is estimated that between 400,000 – 1 million years ago, the discovery and use of fire by humans provided light and warmth at night. It also helped scare off predatory animals, and the smoke would have been effective in keeping insects away. (3) Since then, artificial light has taken many forms, including but not limited to: candles made from animal fat/wax, gas lamps, incandescent bulbs, fluorescents, and the efficient LED lights that are most used today.

Note that fire has a very warm (reddish) color temperature that is very similar to that of a sunrise or sunset. So, starting a fire at night during primitive times would not have negatively impacted circadian rhythms or sleep. Today’s LED and fluorescent bulbs differ significantly — for humans and biodiversity – in that they emit high amounts of short blue wavelengths of light. In humans, blue light stimulates the brain more than other light — halting melatonin production and promoting alertness. This also means that blue light can disrupt the natural rhythms of humans and biodiversity during what should be periods of [natural] darkness.

In short, light is something that society has always needed. You can actually trace 4,000 years of economic growth through its history, but the lighting evolution has also had adverse effects on public health and the environment(4).

Skyline view of a city at night
Photo by Babak Tafreshi

Why Your Lighting Matters

With the spread of electric light, the night sky is no longer filled with just natural light from the moon and stars.  In fact, artificial light (from streetlights, car headlights, and office buildings, for example) causes the sky in urban areas to be six times brighter than the sky in rural locations that are only 9–20 kilometers away. (5) This excessive use of artificial light is also known as light pollution.

According to the International Dark-Sky Association (IDA), components of light pollution include:

  • Glare – excessive brightness that causes visual discomfort
  • Skyglow – brightening of the night sky over inhabited areas
  • Light trespass – light falling where it is not intended or needed
  • Clutter – bright, confusing, and excessive groupings of light sources(6

Many species of plants and animals rely on light/dark cycles to help regulate important biological functions and life cycle activities (e.g. mating, molting, migration, and blooming).

Here are just a few examples showing how artificial light can impact the world’s ecosystems: 

  • Light beams (from high-rises, towers, or lighthouses) can throw off migratory birds that rely on the moon and stars for navigation.
  • Turtles that seek beach areas to lay their eggs now often must compete with tourism and new developments whose bright lights deter females from nesting. The lighting can also disorient newborn hatchlings away from the ocean, often putting them at greater risk of dehydration or predation. (7)
  • When a species can no longer survive in a given area, it may experience habitat loss.
  • Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day. (8
  • Light pollution can disorient insects that rely on bioluminescence or reflections of light to find food or a mate. (9)
TrueLight lighting wave lengths comparison

How Your Lighting can be More Compassionate for Humans and the Environment

Protecting the night sky is a simple yet effective way of conserving biodiversity. Of course, complete darkness is best at night, but opting for warmer lighting is the next best thing since it supports the biological rhythms of humans, plants, and animals.

The TrueLight Luna Red™ Sunset Sleep Light Bulb has adjustable color temperature settings between 3000K (equivalent to evening dusk), and 1000K (a warm red for late at night). This specific color range, combined with built-in dimming, provides ideal light exposure for regulating circadian rhythms and helping the body wind down at night. Unlike conventional lighting solutions that emit junk light and negatively impact melatonin production, this special late-night spectrum does not emit wavelengths that lessen sleep quality.  The TrueLight Luna Red™ Sunset Sleep light bulb simulates natural, relaxing light from candles and is ideal for a variety of indoor and outdoor living spaces (e.g. bedrooms, bathrooms, hallways, nurseries, porches, decks, exterior lighting fixtures, and outdoor walkways).

For those weekends when you’re out camping, having a portable and warmer light source on hand is extremely convenient and compassionate too! The TrueLight Luna Red® Nightlight + Flashlight is a motion-sensing device that minimizes brightness and emits red light only to help keep your sleep/wake cycle on track in the evenings.

In thinking about the light around your home or campsite, just remember this: 

“Light can make people feel good and bring people together, but we need to think carefully about when and where we use it.” – Christopher Kyba, a researcher at the German Research Center for Geoscience(10)


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How Healthy, Signaling Blue Light Boosts Energy and Improves Focus

Home Office Space

Article at a Glance: 

  • Nearly all facets of life depend on the sun’s energy. 
  • The sun produces natural blue light that is responsible for regulating circadian responses. 
  • The 460-500nm range is considered the healthy, signaling blue light spectrum because that is where the human body’s circadian system has peak sensitivity. 
  • Modern technology has caused a noticeable shift to more time indoors under artificial light sources; conventional lighting emits too much of the toxic blue light spectrum that can throw off the body’s circadian rhythm.
  • TrueLight Luna Red lighting is the missing link between natural sunlight and artificial lighting as it harnesses the critical healthy blue light spectrum for greater energy and focuses during the daytime while entraining circadian cues.

All living organisms depend on the sun for nutrients, energy, and survival.  Within the sun’s spectral distribution, the sky-blue range of light is associated with circadian cues that help regulate hormones, mood, and your sleep/wake cycle.  But modern technology has increasingly moved society indoors where artificial junk light often leads to fatigue, stress, and poor sleep.  This calls for a new standard of lighting that harnesses critical sky-blue light to help keep you calm and focused during the daytime while also entraining your circadian rhythm.

What is healthy blue light?

Our eyes detect wavelengths of light between approximately 400-750 nanometers (nm). This is also known as the visible light spectrum.  Within this spectrum, blue light is defined as 380-500nm, which we can further divide into beneficial or harmful wavelengths based on how they affect our vision and health.  Healthy, signaling blue light refers to wavelengths from 460-500nm. (The harmful blue wavelengths live between 380-460nm.)

Graph showing the harmful light vs beneficial light
Photo Source: Blue Light Exposed

Why is signaling blue light important?

When blue light enters the eyes, it stimulates intrinsically photosensitive retinal ganglion cells (ipRGCs) in the back of the eyes and sends signals directly to the suprachiasmatic nucleus (SCN) in the brain.  Research shows that this signaling suppresses the production of melatonin (also known as the sleep hormone), which then promotes greater alertness, focus, and productivity. (1

Our circadian system notably has its peak sensitivity between 460-500nm. (2)   Signaling blue wavelengths are critical for cueing circadian responses — like when to wake up, when to eat, and when to go to sleep. This is an evolutionary function that is hardwired into our DNA to help keep us healthy.

Toxic blue light (within the 400-450nm spike) can have adverse health effects, such as:

  • Fatigue
  • Eyestrain
  • Damage to the retinas, can lead to macular degeneration
  • Social jet lag
  • Stress and anxiety
  • Sleep deprivation
  • Secondary health concerns that stem from poor sleep (e.g. weight gain, mood disorders, heart disease, diabetes, and even cancer)

How TrueLight Luna Red Lighting Supports Energy and Focus During the Day

Most LED lighting technologies to emit large amounts of toxic blue light and have a trough signaling blue light spectrum.  As a result, they fail to communicate daytime accurately to our bodies and misalign our circadian rhythms.  The TrueLight Luna Red light bulb infuses healthy, signaling blue light to promote better energy, focus, and mood during the daytime. With that said, it is intentionally designed without a trough in the toxic blue region. This bulb is a simple yet effective tool for illuminating your home office without disrupting your sleep/wake cycle or leaving you with headaches and eye strain. It can be used in conjunction with or as an alternative to blue-light-blocking glasses.

That’s not all.  The TrueLight Luna Red isn’t just a daytime hack; it comes with complete day-to-night functionality that allows you to adjust the color temperature from 3000K to 1000K. This specific color range, combined with built-in dimming, provides ideal light exposure for both daytime productivity and better sleep at night. In other words, when you use the TrueLight Luna Red light bulb, you have more control over the light in your environment.  The daytime and nighttime settings essentially mimic what you would otherwise be exposed to outdoors, and support your circadian rhythms, as nature intended.


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The Most Effective Nightlight for Promoting Better Sleep

TrueLight Nightlight on a wall

Article at a Glance:

  • Light directly impacts circadian rhythms and sleep patterns.
  • Humans are especially sensitive to blue light; when we are exposed to wavelengths in the blue light spectrum, photosensitive cells in our eyes send signals to the brain to either start or stop producing specific hormones that help keep the body functioning properly.
  • Too much blue light, especially at night, can negatively impact the quality and duration of your sleep. That’s why it’s better to use redder (warmer) lights that support your natural body block.
  • The TrueLight Luna Red Nightlight + Flashlight is a unique 2-in-1 tool that functions as both a nightlight and flashlight for your convenience. It also only emits red like to support your sleep patterns and well-being.
  • This product has both dusk-to-dawn and motion sensors for better functionality and efficiency.

Tired of flipping light switches and tripping over the dog at night? We get it. Climbing out of bed to turn on the lights is inconvenient, somewhat jarring, and can make it difficult to return to sleep. Fortunately, there’s a new solution for illuminating your surroundings without disrupting your circadian rhythm. Introducing the TrueLight Luna Red® Nightlight + Flashlight — a motion-sensing device that minimizes brightness and uses specific wavelengths of light to help keep your sleep/wake cycle on track.

How the TrueLight Luna Red® Nightlight + Flashlight Supports Your Sleep

If you need to illuminate your home at night, the key is to use warmer, redder wavelengths. These are the most effective option because they have a low color temperature — far lower than regular sunlight. This means that you can immerse yourself in red light at night without feeling disoriented or altering your internal clock in the way that exposure to blue light would.

The TrueLight Luna Red® Nightlight + Flashlight emits red light by design to help preserve your body’s melatonin production and promote better sleep.  The device features motion and dusk-to-dawn sensors that automatically shut off with the presence of light. For your convenience, this nightlight can also be used as a flashlight – allowing you to walk around your house late at night without bumping into things or disrupting your sleep.

The TrueLight Luna Red® Nightlight + Flashlight is ideal for:

  • Bathrooms
  • Hallways
  • Nurseries
  • Bedrooms
  • Travel
  • Outdoors and camping