Our Chairman Jan Denneman wrote the commentary of LED professional Review #116. This issue is focussing on the good light. In his commentary he explores why good light could become the next major growth story for the lighting industry. After decades of innovation focused on energy efficiency, LEDs, digital controls and intelligent lighting systems, the industry is entering a new phase. Increasing scientific evidence shows that light affects much more than our ability to see: it can influence our sleep, alertness, wellbeing and performance. With people spending almost 90% of their lives indoors, the quality of indoor light represents an important opportunity. Good light builds on the essential principles of visual comfort, aesthetics and energy efficiency, while adding another dimension: creating indoor environments that work in harmony with human biology. Rather than focusing on a single metric or technology, good light brings together daylight, electric lighting, architecture, controls and user behaviour to better support people throughout the day and night. As Jan explains, this shift could redefine the value of lighting: from infrastructure that simply helps us see to an environmental factor that actively supports health, wellbeing and human performance. At the same time, it creates opportunities for new lighting solutions, products and services, laying the foundation for sustainable growth across the lighting industry. Read the full commentary

If you've searched for ways to improve your sleep, you've almost certainly come across blue-light-blocking glasses. They come in all shapes and colours, from almost clear lenses to bright orange or deep red ones, all promising better sleep, less eye strain and improved wellbeing.But do they really work?The answer is more nuanced than many advertisements suggest. Photo by nacer eddine on Unsplash Why light colour matters Our eyes do much more than allow us to see. They also contain specialised light-sensitive cells, which we call spheres, that communicate directly with the brain's biological clock, located in the suprachiasmatic nucleus (SCN). These cells are particularly sensitive to short-wavelength (blue) light. During the daytime, this is exactly what we need. Exposure to bright, blue-enriched daylight helps keep us alert, improves mood, supports cognitive performance and strengthens the alignment of our circadian rhythm. In the evening, however, the situation changes. If we continue exposing ourselves to bright, blue-rich light from LED lighting, televisions, computers or smartphones, our brain may interpret this as daytime. This can delay the body;s preparation for sleep. The goal in the evening is therefore not to avoid all light, but to reduce the amount of biologically stimulating light reaching the eyes. Dim the lights and choose a warmer light tone. Do blue-light-blocking glasses really work? Yes, but only under the right circumstances. Blue-light-blocking glasses can reduce the amount of short-wavelength light reaching the retina. Research has shown that wearing them during the three hours before bedtime may help some people fall asleep more easily, particularly when they are exposed to bright artificial light during the evening. However, they are not a substitute for good lighting habits. If you're sitting in a brightly lit room with hundreds of lux reaching your eyes, simply wearing lightly tinted glasses may have only a limited effect. Likewise, wearing blue-blocking glasses during the day is generally not advisable, as daytime exposure to blue-rich daylight is essential for maintaining a healthy circadian rhythm. Different glasses Clear or lightly yellow lenses Many glasses marketed for computer use have nearly transparent or slightly yellow lenses. These usually block only a small percentage of blue light. They may slightly reduce glare or visual discomfort for some users, but they generally have little effect on circadian timing. For sleep improvement, their impact is likely to be modest. Amber or orange lenses Amber and orange lenses block a much larger portion of blue wavelengths. These are considerably more effective at reducing circadian stimulation during the evening and are commonly used in scientific research investigating evening light exposure. Wearing them for approximately three hours before bedtime may help support the body's natural transition into the biological night, particularly when exposure to bright indoor lighting or screens cannot be avoided. Deep orange or red lenses The darkest orange or red lenses block almost all blue light and often a significant part of the green spectrum as well. These provide the strongest reduction in circadian stimulation and are sometimes used by shift workers, people with circadian rhythm disorders or individuals who are particularly sensitive to evening light. However, they also significantly alter colour perception and are generally unnecessary for most people. Are they better than reducing screen time? No. For most healthy people, the priority should be achieving a strong contrast between day and night. That means: Plenty of bright daylight during the morning and afternoon. Bright indoor lighting when needed during the day. Dim, warm lighting in the evening. Avoiding unnecessary screen use during the last three hours before bed or switching your screens to night mode. Darkness during sleep. Blue-light-blocking glasses are best viewed as a practical tool for situations where reducing evening light exposure isn't possible, for example, if work requires computer use or if you are travelling. For most people, getting plenty of daylight in the morning is likely to be more important for healthy sleep than simply blocking blue light at night. Rather than asking, "Should I buy blue-light glasses?", a better question is: "Am I getting enough bright light during the day, and am I allowing my evenings to become progressively darker?"

Have you ever noticed how different the world looks at sunrise compared to midday or sunset? In the early morning, daylight has a warm, golden glow. Around noon, it appears bright and crisp. As evening approaches, the light becomes soft, orange and eventually fades into darkness. Photo by Sasha Freemind on Unsplash These changes are more than beautiful scenery. They are powerful biological signals that have shaped human physiology for millions of years throughout our evolution. Our bodies have evolved under the predictable daily rhythm of the sun, and our biological clock still relies on these changing light conditions to regulate sleep, alertness, mood, hormone production and overall health. Understanding how the light spectrum changes throughout the day helps explain why timing matters just as much as the amount of light we receive. What is the light spectrum? Visible light consists of many different wavelengths, each perceived as a different colour. The spectrum ranges from shorter wavelengths, which we see as blue and violet, to longer wavelengths, which appear yellow, orange and red. Sunlight contains all of these colours, but their proportions change throughout the day. Our eyes use this information from the spectrum not only for vision but also to inform the brain about the time of day. Specialised light-sensitive cells in the retina, called intrinsically photosensitive retinal ganglion cells (ipRGCs), or as we call them: spheres, communicate directly with the brain's master biological clock, helping regulate circadian rhythms. Sunrise: A gentle wake-up call Just before and after sunrise, sunlight travels through a thick layer of the Earth's atmosphere. During this journey, much of the shorter blue wavelengths are scattered, allowing more longer wavelengths, reds, oranges and warm yellows, to dominate what we see. Sunrise is an important signal for the biological clock. Even relatively low levels of natural daylight are far brighter than typical indoor lighting and begin preparing the body for the day ahead. As the sun rises, the intensity increases rapidly and more blue wavelengths become available, helping promote alertness. Morning: Building biological momentum As the sun climbs higher, daylight becomes brighter and richer in shorter wavelengths. This combination of increasing light intensity and greater blue content tells the brain that daytime has fully arrived. For this reason, spending time outdoors in the morning is one of the most effective ways to strengthen your biological clock. Midday: Nature's strongest light Around midday, sunlight reaches its highest intensity. The sun is high in the sky, meaning its light passes through less atmosphere. As a result, the full spectrum reaches the Earth's surface with relatively little filtering and is rich in blue light. Even on cloudy days, outdoor light often provides many times more illumination than a well-lit office. The brightness of midday light plays a crucial role in reinforcing the difference between biological day and biological night. Afternoon: A gradual transition As afternoon progresses, the sun slowly moves lower. The spectrum begins shifting again as sunlight passes through more atmosphere. The proportion of blue light gradually decreases while warmer colours become increasingly prominent. At the same time, overall light intensity starts to decline. This gradual change acts as a natural transition, allowing the body to begin preparing for the evening without an abrupt shift. Sunset: Preparing for night During sunset, the atmosphere filters out much of the shorter blue wavelengths.The remaining sunlight appears rich in orange and red tones, creating the warm colours often associated with the "golden hour." This warmer spectrum, combined with rapidly decreasing light intensity, signals to the brain that daytime is ending. As darkness approaches, this stimulates the body to prepare for sleep. The transition from bright days to dim evenings is one of the most consistent environmental signals our circadian system has evolved to recognise. Night: Darkness is part of the spectrum tooAlthough we often think about daylight, darkness is equally important. For thousands of generations, humans experienced nights illuminated only by moonlight, starlight and fire, all relatively dim light sources with very limited biological impact compared to modern lighting. Today's homes often remain brightly illuminated well into the evening using LED lighting that contains substantial amounts of blue light. This creates an environment that no longer resembles the natural progression from day to night. Instead of experiencing a gradual reduction in light intensity, many people effectively extend their biological daytime by several hours. What modern lighting gets wrong Modern indoor lighting is remarkably consistent. Many offices, homes and public spaces use the same lighting throughout the entire day, often with similar brightness and colour temperature from morning until bedtime. This is very different from the dynamic lighting environment humans evolved under. This weak distinction between day and night can reduce circadian contrast and make it more difficult for the body to know when to be alert and when to prepare for sleep. The body's response depends on the entire daily light history, not just a single moment. Six steps to good light While we cannot always work outside, we can design our environments to better reflect the natural rhythm of daylight. Give your eyes a few minutes of bright daylight in the morning. This signals to your body that the day has begun. Spend at least two hours outdoors during the day, especially in the morning. Sit as close to a window as possible during the day. Not enough daylight? Use electric lighting that provides at least 500 lux at eye level. Keep light levels below 10 lux three hours before bedtime. Dim the lights, close the curtains, avoid bright screens, and switch your phone to night mode. Keep light levels below 1 lux at night, even when getting out of bed, and avoid screens whenever possible. These simple changes help recreate the natural contrast between biological day and biological night.

Most people think our eyes exist for one purpose: to help us see. In reality, our eyes have another equally important job. Besides creating vision, they constantly measure the light around us to help regulate our biological clock, hormones, alertness, mood and sleep. To do this, the retina contains three different types of light-sensitive cells. Two are responsible for vision: rods and cones. The third type, known scientifically as intrinsically photosensitive retinal ganglion cells (ipRGCs), but which we’ll simply call spheres, doesn't contribute to vision. Instead, it helps our body understand when it is day and when it is night. Rods: Seeing in the dark Rods are the most sensitive light receptors in the eye. They allow us to see when light levels are very low, such as at dusk, under moonlight or in a dimly lit room. Rods are excellent at detecting brightness and movement, but they cannot distinguish colours. That's why the world appears almost black and white at night. You have around 120 million rods in each eye, making them the most numerous light-detecting cells in the retina. Their job is simple: help you see when there isn't much light. Cones: Seeing colour and detail Cones take over when there is plenty of light. They allow us to perceive colours, read text, recognise faces and appreciate fine details. Humans have three types of cones, each responding most strongly to different parts of the visible spectrum: S-cones are most sensitive to shorter (blue) wavelengths. M-cones respond primarily to middle (green) wavelengths. L-cones respond mainly to longer (red) wavelengths. Your brain combines information from these three cone types to create the rich colour vision we experience every day. There are approximately 6 million cones in each eye, concentrated mainly in the centre of the retina where visual acuity is highest. Spheres: Your body's light sensors Then there are the spheres. Unlike rods and cones, spheres don't help you recognise faces, read books or distinguish colours. Instead, they measure the overall lighting environment and send that information directly to the brain's master biological clock, located in the suprachiasmatic nucleus (SCN). You could think of them as your body's built-in light meter. Their primary task is to let the body know: Is it morning or evening? Is it bright enough to be daytime? Should you stay alert? Is it time to get ready for sleep? Rather than creating vision, spheres help synchronise your body's daily rhythms with the outside world. A well-synchronised circadian rhythm helps you sleep better during the night, have more energy during the day and brighten up your mood. This is why it’s so important to spend time outdoors during the day so your spheres can do their job.

When shopping for a light bulb or reading about good light, you've probably come across the terms lumens and lux. They sound similar, but they describe two very different things. Understanding the difference is essential, especially when it comes to lighting for health and wellbeing. Jan Sleepman What are lumens? Lumens (lm) measure the total amount of light a lamp produces. Think of lumens as the light output of the source itself. The higher the lumen value, the more light the lamp emits in all directions. However, lumens don't tell you how much light actually reaches you. What is lux? Lux (lx) measures how much light, or how many lumen, falls on a surface. For the health aspects of light, that surface is usually your eyes. One lux equals one lumen spread over one square metre. This means lux depends not only on the lamp's output but also on factors such as, the distance from the light source and the direction of the light. In other words, lux tells you how much light is actually available where you are. Why lux matters more for health For your biological clock, it doesn't matter how many lumens a lamp produces; it matters how much light reaches your eyes. Imagine sitting beneath a very bright lamp. If the lamp is high above you or poorly directed, only a limited amount of light may actually reach your eyes. Conversely, sitting close to a window on an overcast day may expose you to thousands of lux, even though the sky doesn't appear particularly bright. This is why chronobiologists and lighting professionals often talk about lux at eye level, rather than the lumen rating printed on the packaging. A practical example Imagine you buy a lamp that produces 2,000 lumens.If the light is spread across a large room, the illumination at your desk might only be 200 lux. Move the same lamp closer or focus the light more effectively, and your desk could receive 500 lux or more. The lamp hasn't changed; only the amount of light reaching the surface has.

During the Guangzhou International Lighting Exhibition (GILE 2026) , deLIGHTed Talks Asia brought together an exceptional group of scientists, clinicians, lighting designers, architects, manufacturers, building professionals and industry leaders. Their backgrounds differed, but they shared one ambition: to accelerate the transition from conventional lighting to Good Light that genuinely improves people's lives. The central question throughout the event was straightforward: How can Good Light move from promising concepts to measurable, verifiable and scalable solutions? Across keynote presentations, panel discussions and Focus Group sessions, speakers explored topics ranging from circadian science and brain function to healthcare, senior living, healthy homes, integrative lighting, lighting design, building performance and owner value. Although the subjects varied, a common theme emerged. The lighting industry has reached a new stage in its development. Technical innovation alone is no longer enough. Future value will increasingly be created by improving sleep, wellbeing, health and the overall human experience inside buildings. That transition also requires a different way of working. Good Light cannot be built on marketing claims alone. It requires scientific evidence, thoughtful design, practical implementation and objective verification. It calls for collaboration between science, medicine, lighting design, manufacturers, building owners and standards organisations. Only then can Good Light become a trusted and widely adopted part of healthy buildings. The discussions during deLIGHTed Talks Asia demonstrated that this transition is already underway. Across disciplines there is growing agreement that lighting should no longer be evaluated only by energy use, efficiency or visual performance, but also by the value it creates for people and for society. The programme featured presentations by leading international experts, including: Robert Lucas: Measuring and Manipulating Light to Support Healthy Rhythms Marijke Gordijn: Good Light, Rhythms, and Circadian Health Jan Denneman: A Wake-Up Call — From Illumination to Human Outcomes Kei Haraguchi / Nichia: Dynasolis™ — Moving Beyond LPW to Create New Value Anne Berends: SunLED Life Science: Near-Infrared Light and Wellbeing Jeff Miller: Beyond Aesthetics — How Designers Translate Science into Human Experience Kevan Shaw: Practical Aspects for Implementing Integrative Lighting Martin Klaasen / VLDC: Future Forum Debrief — Trends, Opportunities and Recommendations for Life Centric Lighting Amardeep Dugar: Lighting Design for Wellness — A Salutogenic Framework Oliver Stefani: Evening Light, Sleep, and Family Wellbeing Zhao Hongyi: Light in Healthcare — From Compliance Lighting to Clinical Environment Design Professor Yandan Lin: Healthy Homes — The Next Upgrade Beyond Smart and Aesthetic Lighting Zheng Hongcheng: No Verification, No True Healthy Light — A Scientific Interpretation Based on EEG Dr. Wei-Jye Lin: How Light Acts on the Brain — From Visual Circuits and Brain Clearance to Verifiable Application Value IWBI / WELL Perspective / Richard Wei-Shun Chang: From Wellness Story to Asset Value Together, these presentations illustrate how rapidly the field is evolving and how Good Light is becoming a multidisciplinary movement. The challenge now is no longer understanding why Good Light matters, but how to implement it responsibly, verify its impact and deliver measurable value for people, buildings and society.

The Good Light Group is pleased to welcome Kevan Shaw as an advisor. Kevan is an internationally respected lighting designer with more than 40 years of experience in architectural, museum and urban lighting, and currently serves as a Director of the International Association of Lighting Designers (IALD). Sunset in Iceland Kevan will strengthen our work particularly in the field of lighting design, helping to further integrate health and wellbeing into design practice. His extensive international network, close ties with the IALD, and experience in developing industry guidance and white papers will be invaluable as we expand our practical recommendations on integrative lighting design. We are delighted that Kevan is joining our growing team of advisors and look forward to working together to help make good light an integral part of healthier buildings and healthier lives. Kevan Shaw

Daylight saving time gives us longer, brighter evenings, but it can also disrupt our natural body clock. Even weeks after the clocks change, many people still feel more tired, find it harder to fall asleep, or struggle to wake up in the morning. The reason is simple. Our body clock is primarily regulated by light. When the clocks move forward by one hour, our social schedule changes overnight, but our body clock does not. It needs time and the right light signals to adjust. Photo by Solving Healthcare on Unsplash One of the best ways to adapt is to get plenty of light in the morning. Morning light is the strongest signal that tells your body the day has started. Try to get outside as soon as possible after waking up. A short walk, breakfast on the terrace, or cycling to work can make a significant difference. Research suggests that most adults need at least 500 lux at eye level during the day to support alertness and help regulate their body clock. Outdoor daylight easily exceeds this level, even on a cloudy day. If spending time outdoors is not possible, sit close to a window or use bright, high-quality electric lighting to reach approximately 500 lux at eye level during the first part of the day. The challenge with daylight saving time is that your body may still be running on the old schedule. If you normally go to bed at 22:00hr, your body may feel as though it is only 21:00hr. As a result, you may not feel sleepy when you want to go to bed. Late evening daylight can make this adjustment even more difficult. Bright light in the evening tells your body that it is still daytime. This delays your body clock and slows down the natural processes that prepare you for sleep. The result can be difficulty falling asleep, poorer sleep quality, and increased tiredness the next day. To help your body prepare for sleep, keep the three hours before bedtime as dim as possible. Close curtains or blinds, dim indoor lighting, avoid bright screens, and switch your devices to night mode. Ideally, keep light levels below 10 lux at eye level during the last few hours before bed. A darker evening environment allows your body to produce melatonin naturally and prepare for a restorative night's sleep. Most people adapt to daylight saving time within a few weeks. You can speed up this process by following a simple rule: get as much light as possible in the morning and as little light as possible in the evening. Daylight saving time changes the clock. Good light helps your body catch up. The right light at the right time supports better sleep, more energy, a better mood, and a healthier life.

A summary of the article by Jan Denneman and Dave Hollingsbee, published in Arc, a magazine for architects and interior designers. For years, the lighting industry has focused on three key goals: functionality, design, and sustainability. We have made remarkable progress in energy efficiency, circular manufacturing, and smarter lighting controls. But there is a fourth dimension that deserves equal attention: sleep, human health and performance. Photo by copernico on Unsplash One of the most compelling arguments comes from the “3-30-300 rule,” which highlights how organisations typically spend around €3 on utilities, €30 on space, and €300 on people for every square foot of building space. While lighting is often evaluated based on energy savings, the greatest financial impact may come from its influence on employees. Even a 1% improvement in productivity or reduction in absenteeism can save hundreds of thousands of euros annually, far exceeding typical lighting energy costs. Recent discoveries in chronobiology support this perspective. Researchers have shown that light does much more than enable vision; it regulates our internal body clock, sleep quality, alertness, and overall health. Modern indoor lifestyles often expose us to too little daylight during the day and too much artificial light in the evening, disrupting natural circadian rhythms. The result can be poorer sleep, reduced concentration, and lower workplace performance. We introduced the concept of a “light diet,” comparing light exposure to nutrition. Just as a healthy diet supports physical wellbeing, the quality, intensity, and timing of light exposure play a critical role in human health. This means lighting should no longer be considered background infrastructure, but an active contributor to wellbeing and productivity. We advocate for greater access to natural daylight, and for electric lighting that compensates the lack of natural daylight. We want to encourages architects, designers, developers, and policymakers to move beyond compliance and energy metrics and instead focus on measurable human outcomes. Ultimately, the message is clear: sustainability is not only about reducing energy consumption. Truly sustainable buildings must also support the health, resilience, and performance of the people who use them. The challenge facing the industry is no longer whether healthier lighting is possible, it is about entering this new chapter of the lighting industry. Read the full article here

We’ve organised our 25th Good Light Group meeting. The topics included: Jan Denneman with the Good Light Group news. Lawrence Lin presents an update on the Good Light Group Asia & more info about the deLIGHTed Talks Asia. Maarten Voorhuis shares his insights into the use of the light-measuring function on the Apple Watch. Photo by Jonatas Daniel on Unsplash Missed the Good Light Group Meeting? Watch the presentions online here: Jan Denneman - Good Light Group news Lawrence Lin - Good Light Group Asia Maarten Voorhuis - the light-measuring function on the Apple Watch Lawrence Lin - deLIGHTed Talks Asia

An epidemiological study (Stevenson et al., 2024) with participants from the UK found that people who had more ultraviolet, or UV, light exposure tended to live longer compared to people with less UV exposure. That finding might sound strange, because exposure to UV light – which is part of sunlight – is commonly communicated as a health risk factor. In fact, too much UV exposure can increase the risk of skin cancer. These new findings, however, suggest a more nuanced relationship between UV light and health, especially in cloudy, low-sunlight countries like the UK. Photo by Elizeu Dias on Unsplash The findings are based on data of 395,086 people from the UK Biobank study. For their study, the researchers quantified UV exposure from two proxies: (i) behaviour in terms of visits to solariums or sunbeds, and (ii) meteorological data of sunlight reaching the participants’ residential area. These data in turn were analysed with respect to the prevalence of deaths from heart disease, cancer, and other causes. The main finding was that people with higher UV exposure had a lower risk of dying overall, including a lower risks of dying from cardiovascular disease and cancer. Solarium users had about a 15% lower risk of death overall compared with non-users, and people living in sunnier parts of the UK also had lower death rates. In their publication, the authors discuss the mediating role of vitamin D, which is produced by the skin when exposed to UV-B light. An additional possibility discussed is UV-A light, which may help release nitric oxide in the skin. Nitric oxide, in turn, is suggested to relax blood vessels, lower blood pressure, and thereby support heart health. Importantly, these results do not mean tanning endlessly is a good idea. The researchers mention that higher UV exposure could be linked to more melanoma cases. Hence, the take-home message is not “go and bake in the sun.” Rather, it means that overly strict avoidance of sunlight might carry negative rebound effects for health, which should be considered in the communication of health risks associated the UV – sunlight – exposure. Since public health advice often focuses on the dangers of UV exposure, a more nuanced view might be warranted. Place of residence should be considered, as these findings from a UK cohort show, since countries like the UK, are limited in sunlight exposure with an increased prevalence of low vitamin D. Based on research from the UK Biobank cohort study: Stevenson, A. C., Clemens, T., Pairo-Castineira, E., Webb, D. J., Weller, R. B., & Dibben, C. (2024). Higher ultraviolet light exposure is associated with lower mortality: An analysis of data from the UK biobank cohort study. Health and Place, 89. https://doi.org/10.1016/j.healthplace.2024.103328

We are delighted to welcome ClearLight as a new participant in our Group. At ClearLight, they believe that the way we approach lighting is fundamentally flawed. For decades, lighting has been designed around standards, efficiency, and cost reduction, while the human perspective has largely been overlooked. Good lighting, however, does far more than simply illuminate a space. It affects our biology, our natural rhythms, and our overall wellbeing. It influences how we feel, how we perform, and how we recover. “In the Good Light Group, we have found like-minded professionals who share this belief. Together, we are working towards a necessary paradigm shift: from lighting designed for standards and energy efficiency to lighting designed for people,” says Maurijn, co-founder of ClearLight. More info about ClearLight