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:

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 c

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 evoluti

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 ganglio

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 t

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: Ho

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. P

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

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 relatio

Light is more than something you see. When it enters your eyes, it reaches parts of your brain that regulate your sleep, your mood, your alertness, and your long-term health. This happens every time you step outside, sit under a lamp, or look at a screen, whether you notice it or not. And the pattern of light you live in, bright or dim, day or night, shapes how well your body works. How light shapes your body clock Every cell in your body follows a roughly 24-hour rhythm. Thi

Jeroen Bosch Hospital (JBZ) in Den Bosch, the Netherlands, has reported encouraging early results from a new night-shift system called a “chrono-schedule”. In a pilot study, nurses working under the new system said they felt less exhausted after night shifts, had less difficulty staying awake, and recovered more quickly afterwards. Photo by Amir Arabshahi on Unsplash Instead of working a full night shift, staff worked shorter shifts from 8.00 pm to 4.00 am or from 4.00 am to

Sleep is fundamental to our health, performance, and wellbeing — yet it is increasingly disrupted by our everyday’s actions and the way we design and light our buildings. This CIBSE-approved CPD course explores the science of sleep, our internal body clock, and how integrative lighting design can actively support healthier sleep–wake rhythms. Photo by Gregory Pappas on unsplash Understanding sleep: more than just “switching off” A clear overview of what sleep actually is, bre

Sleep doesn’t start when your head hits the pillow, it begins hours earlier with the signals you send your brain. One of the most important signals is light. To support deep, restful sleep, it’s recommended to keep light levels below 10 lux starting three hours before bedtime. Photo by Giorgio Trovato on Unsplash How Light Affects Your Sleep Your brain uses light to decide whether it’s time to be awake or asleep. Bright light in the evening, especially artificial lighting a

Last week, Jan Denneman had the opportunity to speak at Light + Building in Frankfurt as Chair of the Good Light Group. What continues to strike him is this: we spend around 90% of our time indoors, yet the light around us is fundamentally misaligned with our biology. The impact is not subtle. It shows up in poor sleep, low energy, reduced wellbeing, and long-term health risks. And still, we treat this as normal. The reality is simple. During the day, most indoor environments

Spending time outdoors is ideal, but many of us still spend large portions of the day inside. When natural daylight is limited, optimizing your indoor light environment becomes essential for maintaining energy, focus, and a healthy daily rhythm. These two simple steps can make a big difference. Photo by Surface on Unsplash Step 2: Stay within one meter of a window When you’re indoors, your proximity to natural light matters more than you might think. Light intensity

In our busy, screen-filled lives, it’s easy to spend most of the day indoors. But making time to step outside, particularly in the morning, can have a huge impact on your overall health and well-being. In fact, scientists recommend spending at least 2 hours outside during the day, with a good portion of that time in the morning if possible. Photo by cal gao on Unsplash The power of morning light Morning sunlight plays a vital role in setting your body’s brain clock, also k

A blog by Ivo Habets “Natural daylight during office hours improves glucose control and whole-body substrate metabolism” The circadian timing system regulates many processes in the human body. While it is best known for controlling our sleep–wake cycle, metabolism also follows a strong daily rhythm. This includes processes such as glucose regulation, insulin sensitivity, and substrate use, which vary across the day in a coordinated manner. The main entrainment signal for the

A blog post by Dr. Aida Farshadi For millions of years, humans lived under the full spectrum of sunlight. Our physiology evolved not just with visible light, but also with near-infrared light (NIR), an invisible wavelength that makes up nearly half of the sun's energy reaching Earth. Photo by Todd Rhines on Unsplash What is near-infrared light and why we're missing it? Near-infrared sits just beyond the red end of the visible spectrum, in the 700–1100 nm wavelength range. Un

Summary of Ulysse Dormoy’s article “What Is Light?” “It occurred to me that since I started posting articles and thoughts about light, I haven’t yet raised the question - ‘ What is Light? ’ – actually, in 30+ years in the lighting industry it's not a question I've challenged myself with.” – Ulysse Dormoy Light exists in a state of duality. It behaves both as a wave and as a particle, a phenomenon known as wave–particle duality. Like the classic “chicken or egg” question, it c

It’s Blue Monday, often described as the “most depressing day of the year”. Three weeks in the new year, mostly in cloudy, rainy of snowy weather has brought the mood down of many. Photo by Pars Sahin on Unsplash Here are some tips and tricks to help you get through this day. Boost your mood naturally Get a lot of daylight: We recommend spending up to two hours outside, especially in the morning. But every short walk outside does already help. Move your body: If you’re goi