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We are excited to share the release of the updated Good Light Guide, a comprehensive resource that delves into on the science of lighting to help you understand what conditions good light should meet. At the Good Light Group, we are passionate about making people aware that they need good light. Daylight, but if this is not possible, people need good artificial light indoors that imitates the sun as much as possible. We updated some of the numbers according to new research. Now we added the minimal recommended light levels. Our guide is regularly updated to align with the latest research, ensuring that you always have an up-to-date guide for developing your lighting solutions. Click here for the short version of the Good Light Guide Or here to download the Good Light Guide

On the 16th of May, our group, together with the Society for Light Treatment and Biological Rhythms (SLTBR), the Daylight Academy (DLA), the International Association of Lighting Designers (IALD), and Luger Research (LR), organised and presented the “deLIGHTed Talks” Mimicking Daylight indoors – Why, What, How? lectures. The videos of these lectures are now online, as well as the panel discussion! "Daylight – See me, feel me, touch me, heal me!" by Yvonne de Kort During the Delighted Talks webinar, Yvonne de Kort, a researcher and expert in environmental psychology of human-technology interaction, delivered a presentation on the scientific evidence for the importance of daylight and sunlight indoors for human health and wellbeing, and the different mechanisms through which these effects (may) emerge. watch the lecture here "Daylight in buildings – How much we need and get" by Joannes Zauner During the webinar Joannes Zauner presented real-world projects that successfully optimized daylight levels during the design phase and integrated artificial lighting to boost light levels during winter. Watch the lecture here Panel discussion and the Q&A. Watch it here

Science advisors and board members of the Good Light Group have written a position paper on the effects of good light and plea for including good light in norms and regulations. The summary of this paper is: Good indoor lighting is essential for enhancing healthy body rhythms, sleep quality, alertness, mood and productivity in the workplace. However, current indoor lighting practices and recommendations prioritise vision over health, leading to disruptions in our biological clock and alertness. Limited exposure to natural daylight also contributes to this problem. Scientific recommendations for people with regular daytime schedules call for higher light levels during the day and lower levels in the evening and night. Adopting these good lighting recommendations in norms and regulations will lead to improved indoor lighting and overall well-being of individuals as well as having a significant socio-economic impact. Photo by Priscilla Du Preez on Unsplash The article discusses the dark side of indoor lighting and how it’s disturbing the biological clock, with adverse effects on sleep. It also explains how indoor lighting throughout the day, boosts alertness and mood. And concludes that this is a bright idea that benefits individuals and society. You can read the article here

BakkerElkhuizen offers a range of ergonomic office solutions. Based on research and knowledge, the company's products are designed focused on healthy posture and reduce the risk of repetitive strain injuries. They realized that lighting plays a major role too in optimizing fitness, health and overall mental wellbeing of computer users. That’s why they wanted to join our Group and their dedication to improving the health and wellbeing of office workers makes them an ideal new participant. BakkerElkhuizen created an innovative bio-dynamic, human centric, lighting fixture. Called EnergyByLight. It provides the right task and ambient light at the right time for the (home) workspace. The automatically changing intensity and colour temperature, similar to the sun, promotes a sense of wellbeing and productivity by supporting your bodies natural circadian daylight rhythm. By nature, our bodies have adapted to the sun, providing us with energy throughout the day and a resting period during the night. The EnergyByLight is no different; it's not an artificial light but a biodynamic, human-centric light that mimics the colour temperature and brightness of natural daylight found at your location throughout the course of a day, regulating your circadian rhythm. More info about BakkerElkhuizen Expert video Mood video

Not only did we celebrate Kingsday last week in the Netherlands, but we also had the privilege of seeing our co-founder and board member, Marijke Gordijn, receive the Knight in the Order of Oranje Nassau award for her volunteer work in table tennis and her significant contributions to various associations focused on sleep, chronobiology, and light treatment, including the Good Light Group. Marijke's dedication to making scientific knowledge more accessible to society is inspiring, and we extend our heartfelt congratulations on this well-deserved honour! 🎖️

The Good Light Group, in collaboration with the Society for Light Treatment and Biological Rhythms (SLTBR), the Daylight Academy (DLA), the International Association of Lighting Designers (IALD), and Luger Research (LR), is set to host the 5th edition of the "deLIGHTed Talks" webinar. "Mimicking Daylight indoors – Why, What, How?", will take place on May 16th from 16:00 - 17:30 CEST and is free to join. Attendees can listen to several talks from lighting experts on the importance of mimicking natural daylight indoors for health and wellbeing, as well as designing spaces with optimal daylight levels. The webinar will take place as part of UNESCO's International Day of Light 2023 event. This edition of deLIGHTed Talks is an interesting opportunity for anyone interested in lighting design, architecture, or health and wellness to learn from experts in the field. More info and register here

The right lighting can make a world of difference in your daily life! That’s why we, together with Johan Krijl developed whiteboard animations that highlight the importance of good lighting. Many people spend much of their day in semi-darkness, even with the lights on. This lack of proper lighting can have a significant impact on our biological clock, affecting our sleep, mood, and overall well-being. Indoor lighting provides no more than 150 lux, while outside on a sunny day, the lux level can reach 125,000. Good light in your eyes is crucial to set your biological clock properly, and that's why it's essential to get at least half an hour of sunlight in the morning. If that's not possible, installing electric light that mimics daylight can also help. Working on the animations has opened Krijl's eyes; before this project, he did not know how important good light is. He now has two desk lamps on the sides of his desk. This way, on busy days when he doesn't have time to go outside, he still has enough light. His sleep improved and can concentrate better. Now when he doesn't turn on the light he really misses it, the sunny atmosphere. Not to mention what light does to your mood. There is a reason why people can get dejected in autumn and winter. Taking a walk every day can help. On the one hand through the exercise, but certainly also through the light falling into your eyes. The blog of Johan Krijl

Good light is essential for our health and well-being, and actually to realise . That is why we have launched our 30-day good light challenge. We want to encourage people to take steps to improve their lighting situation and share their experiences. We know that not everyone is ready to commit to these 30 days. But with these three simple steps, you can still enjoy good light by simply making small improvements in your own home or office. That is why we have added a new feature on our website that allows you to upload a photo of your lighting situation so that we can share it on our website and social channels. Whether it's a well-lit workplace with daylight or electric light during the day or a dimly lit living room in the evening. Maybe you will inspire someone else to take the next step towards good light and better health and well-being. Please let us know if you are happy with your indoor light situation and what you would like to improve.

Using Forced Desynchrony designs to investigate the impact of circadian rhythms and homeostatic sleep pressure on human sleep. A blog by Renske Lok Sleep and wake are tightly regulated by an interplay of the circadian system and homeostatic sleep pressure, more info. Many of our bodily processes including alertness, cognitive performance, physical performance, and sleep, are influenced by both systems. To better understand and design targeted interventions, it is crucial to determine the contribution of each of these systems. For example: Suppose sleep was only driven by homeostatic sleep pressure. In that case, one could fall asleep at any time of day as long as one has been awake for long enough. Simultaneously, suppose sleep was only driven by the circadian system. In that case, one could only fall asleep only when the internal clock dictates to do so. We now know that sleep, in fact, is driven by a combination of circadian clock phase and homeostatic sleep pressure; one can only fall asleep when one has been awake for long enough, and their circadian clock tells them to do so. Photo by Kinga Howard on Unsplash To determine the influence of homeostatic sleep pressure and circadian clock phase, a complicated experimental design is necessary in which one can separate these effects. One of the ways to do so is by conducting a Forced Desynchrony (FD) experiment. FD experiments investigate the impact of the internal clock, or circadian rhythm, and the duration of prior wakefulness, homeostatic sleep pressure on a desired output measure. In an FD experiment, participants are subjected to an artificially imposed sleep-wake cycle that is longer or shorter than 24 hours and, in part, is out of sync with their natural circadian rhythm. For example, in a typical FD experiment, participants might be subjected to a 28-hour day, where they are kept awake for 16 hours, followed by 12 hours of sleep. This means that their sleep and wake times will gradually shift later over time, while the circadian clock free runs, unsynchronized with the 24-hour day. Researchers can use a variety of measures to study the effects of forced desynchrony on the body. For example, they might monitor the participants' sleep, hormone levels, or alertness throughout the experiment. They can then use mathematical calculations to calculate the contribution of the circadian clock and homeostatic sleep pressure, as they know precisely at which circadian clock time a measurement took place, as well as the amount of build-up homeostatic sleep pressure at that time. One of the key findings from forced desynchrony experiments is that the body's natural circadian rhythm is not precisely 24 hours long. In fact, the average length of the circadian rhythm is slightly longer, closer to 24.2 or 24.3 hours. This means that the body needs to constantly adjust to the timing of external cues in order to stay in sync with the 24-hour day. FD experiments can also shed light on the effects of disrupted sleep-wake patterns on health and well-being. For example, FD experiments have shown that people who work night shifts and thus are awake when the circadian system promotes sleep may be at increased risk of various health problems, including obesity, diabetes, and cardiovascular disease. Understanding how the circadian clock and homeostatic sleep pressure contribute to these disruptions can help researchers develop better strategies for mitigating these risks.

Last week our 14th group meeting was held online in which two new board members were introduced and Joachim Stormly Hansen from Ocotune took the stage to present a fascinating presentation about measuring how much light people do actually receive. Joachim Stormly Hansen talked about measuring and logging good light, the minimum recommendations for light we need during daytime, evening and night and a new light sensor they are developing that can measure good light, is small and gives you insight in your light history and amount of good light. He elaborates further on how this sensor measures light. You can watch all three parts of the meeting here: Virginie Gabel Roger Sexton Joachim Stormly Hansen

It is almost daylight saving time, also known as summer time. This weekend in most countries in Europe and next weekend in most countries in America, we have to set our clocks ahead one hour. It was introduced in Europe during World War I and adopted again during World War II to extend the amount of daylight in the evening. But morning light is the most important thing for our health and sleep! Waking up and tuning your biological clock to the time of day is most important. During summer time, we have too little morning light and too much evening light. This disturbs our biological clock and has a negative effect on the quality of our sleep, energy level and alertness during the day and on our mood. It may even lead to health problems. The shift of the clock with one hour in itself also causes problems. 1. We lose one hour of sleep, which is difficult to adjust to for many people. This can lead to daytime fatigue, moodiness and reduced productivity. Especially for children. 2. A disrupted sleep pattern can also lead to more accidents. Especially in the early days after the shift there is an increased risk of accidents because people are more tired and less able to concentrate, leading to errors in judgement and reduced reaction time. While Europe continues to debate the benefits of daylight saving time, Mexico has already abolished it. In April 2021, the Mexican government announced that it would no longer observe daylight saving time, based on health concerns and the disruption of sleep patterns. The decision was welcomed by many Mexicans, who had long complained about the confusion and problems caused by the clock changes twice a year.

I first came across the GLG a couple of years ago when Jan Denneman (Good Light Group board member) gave me a call about it. It’s an area I have been interested in for well over 20 years since I was lucky enough to be involved in a small way with some early research. Through the years I have kept myself up to date as more evidence is consolidated and was particularly excited to read the metanalysis last year from ‘The Manchester Group’ leading to specific lighting design advice, now I gather included in a draft version of ISO 8995. The company I work for, Stoane Lighting, are sponsors of the Good Light Group. They are also active members of the industry associations Lighting Europe and the Lighting Industry Association. They produce dedicated luminaires mostly for the lighting design fraternity. The foundation aim of their manufacturing approach is minimum environmental impact, whether considering the efficiency of the active components involved or the through-life embodied carbon. Experience in all these areas with Stoane gives me I think an interesting bucket of experience to put on the table at meetings within the Good Light Group, and with a feeling of honour I have accepted the invitation to join their Board. What are my feelings about the Good Light Group? Some of their actions are already tackled by the other organisations I have mentioned above. But what I don’t see outside of the Good Light Group is one independent organisation focused entirely on this one topic. Connecting university research; lobbying for legislation; spreading awareness via its own events and SM; championing good lighting practice on its website; producing good light guides aimed at different sectors; supporting initiatives in the care home segment (is there one crying out more strongly for its lighting to be thought through?,)…. I could go on. I always enjoy working with people who believe strongly in a subject and find the energy to do something about it. What will my specific contribution be? I don’t know what will happen further down the road and will put my shoulder to any cause that makes sense to me. But at this juncture I can think of three things: practical, in the market, trials of The Manchester Group’s daytime lighting advice with University College London; an initiation of links between dementia organisations and the Good Light Group and working with the Good Light Group’s Work Group Science to produce lighting design healthy light guidance - here interfacing with the IALD will be essential.