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We've got a new participant, UPRtek. They are pioneers in developing high-quality solutions for light meters, flicker frequency meters, spectrometers, and spectroradiometers. “We hope to join The Good Light Group in promoting the importance of good lighting to the world, as UPRtek's mission aligns with that of The Good Light Group. Here, there are many pioneers in the lighting industry, and we believe that good lighting also requires excellent professional measuring instruments to complement it.” Hedy Lee | Deputy Sales Manager UPRtek More info about UPRtek

16 April, 15:00 - 16:30 CEST ​ The Good Light Group, together with the Society for Light Treatment and Biological Rhythms (SLTBR), the Daylight Academy (DLA), and Luger Research (LR), are organizing and presenting the “deLIGHTed Talks” lectures. The lectures are free to join. ​ Programme ​15.00 Introduction Welcome, Introduction by Charna Dibner, Geneva University ​ 15.10 by Kathryn Reid, Northwestern University ​ 15:30 Diabetes in the daylight: metabolic benefits through natural office lighting? by Jan-Frieder Harmsen, RTWH Aachen University ​ 15:50 Panel discussion Including Q&A with the Audience Panelists: Kathryn Reid & Jan-Frieder Harmse Moderation: Charna Dibner More info

Renske Lok, Ph.D. Stanford University, Department of Psychiatry and Behavioral Sciences Beyond its role in vision, light plays a significant role in shaping our physiology and behavior. Light exposure at night influences alertness, cognitive functioning, and melatonin production. The effects of light on these non-visual functions are contingent upon factors such as intensity, timing, temporal pattern, and spectral properties of light exposure, and there is compelling evidence that these dependencies may vary with age. Photo by Renske Lok Aging and light intensity Numerous studies investigating the non-image-forming effects of light intensities have been conducted in young, healthy adults (18-40 years). However, an increasing number of studies underscore that such effects may not be the same over the lifespan. For example, when investigating how evening light of different intensities (ranging from 5 to 5000 lux) relates to melatonin suppression in preschool-aged children (~3 to 5 years), researchers found that melatonin levels were suppressed across the full range of intensities examined (Hartstein et al., 2022). In contrast, in those aged 18-44, half of the fitted maximal melatonin-suppressing effect of light is estimated to be induced by ∼50 – 130 lux (Cajochen et al., 2000). While there wasn't a clear intensity-dependent response in preschool children, the lowest quartile of light intensities (5–40 lux) showed a notably lower average melatonin suppression than the higher quartiles, indicating that the chosen light intensities might have been too high for this age group. On the other side of the spectrum, older adults (~60 years and up) exhibit a lower sensitivity to light compared to their younger counterparts, suggesting that older individuals may require increased light exposure to attain the same benefits experienced by the younger population (Duffy et al., 2007). Age-related ocular conditions, such as cataracts, lens yellowing, and behavioral changes, contribute to decreased light exposure for older individuals. This population often resides in dimly lit environments and has restricted access to natural daylight, ultimately diminishing circadian light sensitivity by limiting the amount of light reaching the retina. Aging and light spectrum The prevailing consensus is that the circadian system exhibits its highest sensitivity to light at approximately 480 nm in wavelength. This particular wavelength maximally stimulates the melanopsin-sensitive photoreceptor, which plays a predominant role in the non-visual effects of light. While other photoreceptors, such as those sensitive to shorter wavelengths (S-cone) or longer wavelengths (M-cone or L-cone), also contribute to non-image forming effects, their impact is comparatively less significant than that of the melanopsin-sensitive light cells. A recent study proposes that the involvement of other photoreceptors in the non-image-forming effects of light may change over the lifespan (Najjar et al., 2024). In a within-subject design, researchers exposed young and older individuals to narrow-band lights ranging from 420 to 620 nm for 60 minutes at night to assess the effects on melatonin suppression. The study found a straightforward pattern in young adult participants (~25 years): melanopsin solely drove melatonin suppression at all time intervals. The peak sensitivity was identified at 485.3 nm after just 15 minutes of light exposure. However, in the older group (~59 years), the process was jointly driven by melanopsin, the short-wavelength-sensitive (S)-cone and medium-wavelength (M)-cone, with a stable peak sensitivity around 500 nm at 30, 45, and 60 minutes of light exposure. This suggests that as humans age, there's a shift from a reliance on melanopsin alone to a more intricate interplay of photoreceptors in regulating melatonin suppression. Future perspectives Collectively, these studies mark the initial strides toward a nuanced comprehension of the non-image-forming effects of light across diverse life stages. The shift from the reliance on melanopsin in youth to the intricate interplay of photoreceptors in older age, along with the notable impact of low-intensity evening light on children versus higher-intensity lighting in adults, opens doors for tailored approaches to light therapy. It underscores the crucial role of a well-considered lighting environment at every stage of life and emphasizes the significance of careful sample selection in research studies. However, a need remains to unravel how a combination of different light intensity and spectral composition variations influence melatonin suppression and whether these lighting effects extend to other non-image-forming effects, such as mood and cognitive performance. Further exploration in these areas will contribute to a more comprehensive understanding of the intricate, multifaceted relationship between light and well-being across the lifespan. References Cajochen, C., Zeitzer, J.M., Czeisler, C.A., Dijk, D.J., 2000. Dose-response relationship for light intensity and ocular and electroencephalographic correlates of human. Behavioural Brain Research 115, 75–83. Duffy, J.F., Zeitzer, J.M., Czeisler, C.A., 2007. Decreased sensitivity to phase-delaying effects of moderate intensity light in older subjects. Neurobiology of Aging 28, 799–807. Hartstein, L.E., Behn, C.D., Akacem, L.D., Stack, N., Wright Jr, K.P., LeBourgeois, M.K., 2022. High sensitivity of melatonin suppression response to evening light in preschool‐aged children. Journal of pineal research 72 (2), e12780. Najjar, R.P., Prayag, A.S., Gronfier, C., 2024. Melatonin suppression by light involves different retinal photoreceptors in young and older adults. Journal of pineal research 76 (1), e12930.

To determine if you’re living and working in good light, its’ best to spend at least 2 hours outdoors in daylight each day. Daylight is always good for people. However, if you are indoors, how can you ensure you have sufficient light indoors? To determine if indoor lighting is sufficient to improve your health, sleep and happiness,  we need to measure the intensity of light that reaches our eyes. Light levels are typically measured in ‘lux’ which quantifies the amount of light per square meter and thus indicates the intensity of light perceived by our eyes. Lux helps to understand the brightness or dimness of a space. The recommendation is to have indoors at least 500 lux light in your eyes, which is rather easy if you are close to a window. If you are further away of a window you need to compensate the lacl of daylight with electric light to get to 500 lux. Think of it like this: if you're in a room with large windows and plenty of sunlight coming in, it will have a high lux level. But if you're in a dimly lit basement with only a small lamp, it will have a low lux level. Because our eyes adjust to the lux level of a room, they aren’t a reliable measurement tool. That's why we use a mobile app or a lux meter to measure light. Lux is important because it affects visibility and can influence productivity, health and mood. For example, in workplaces, having the right amount of light at the right time can help you work more efficiently and boost your mood. Our recommendation is to aim for at least 500 lux during the day and less than 10 lux during the night.

This Friday March 15th, marks World Sleep Day. The theme of this year is Sleep Equity for Global Health. Good light (daylight or electric light that mimics daylight) is essential for good sleep. If you think you need darkness for better sleep quality, you are completely right. You need darkness at night. But you also need bright light during the day. Daylight is the best! Consider yourself sitting in a dimly lit room during the afternoon for around half an hour. How would you feel? •             A: Bright, active and full of attention •             B: Awake, but not very alert •             C: Sleepy, hard to keep my eyes open Photo by Clint Patterson on Unsplash Did you answer not very alert, or even sleepy? So, this is what a lack of light can do to your brain! With more daytime light you feel active and you sleep better at night. So, if you want to improve your sleep, focus on the right light at the right time. Here are 4 simple rules: 1.           Go outside during daytime as much as possible 2.           Use bright light in the morning 3.           Dim your lights towards dinner 4.           Make the night as dark as possible More info on our try page

We have a new partner! Utilicht, with over 35 years of experience in lighting advisory and plan development for diverse projects and clients – ranging from individuals to hospitality, retail, and large utility projects. Through collaboration with our group, Utilicht can offer innovative and effective lighting solutions tailored to the preferences and requirements of different users while giving the health and well-being of the users also a priority. Utilicht also supports our mission to enhance the quality of life for millions of people worldwide by good light. utilicht.nl

Jan Denneman says, "There's hardly a living creature that willingly stays indoors, with a few exceptions." We're all familiar with the benefits of exercise, a balanced diet, and enough relaxation for good health. But did you know that light plays an equally crucial role? Those who maintain a healthy exposure to good light tend to sleep better, experience reduced stress, more energy and happiness. "The influence of light on our health," Jan Denneman informs you about the effects of light on human well-being and shares practical advice. The masterclass is in Dutch, for the link please see the end of this article. In winter, when daylight hours are shorter, how does this impact us as humans? "At this time of year, we often feel more tired, down, and our circadian rhythms are frequently disrupted. Scientifically proven, people tend to be less happy during the winter compared to summer, simply because you get insufficient daylight." Why is daylight essential for a happier life? "It's how nature operates. Just as a compass aligns with the Earth's magnetic field, humans are designed for daylight. All life on Earth – plants, animals, and even microbes in the sea – relies on daylight. With a few exceptions (like moles), no living creature voluntarily chooses to stay indoors. However, centuries ago, humans started spending more time indoors, which goes against our natural instincts and internal body clocks." How does our biological clock function? "The biological clock, located in our brain, prepares our bodies for upcoming events, such as a good night's sleep. Synchronization with real-time is crucial for a properly functioning biological clock. If you naturally wake at 7 am and sleep at 11 pm, your biological clock is likely in good shape. But, if you consistently wake up tired and rely on an alarm clock, your biological clock may be disrupted. Scientific studies indicate that you can only synchronize your biological clock with light. Apart from rods and cones, which enable vision, our eyes also contain spheres linked to the biological clock and mood regulation. These cells require more light than those responsible for vision. Therefore, I always carry a light meter to ensure I'm exposed to sufficient light to stimulate these cells." How do we know if we're receiving sufficient light, and if these spheres are doing their job? "According to research, during daylight hours (between 7 am and 6 pm), you should receive at least 250 lux of natural light or 400 lux of artificial light through your eyes. Convenient apps like Light Meter for the iPhone can measure illuminance. Outdoors, you'll naturally receive 250 lux or more when the sun is up, but indoors, unless you're near a window, you'll need to adjust lighting. However, in the evening, aim for much lower light levels, ideally less than 10 lux, to prepare your body for sleep." What are some practical tips for increasing daylight exposure during dark days? "Morning light is most effective, so go outside when the sun rises. Even on dark, rainy days, outdoor light is significantly stronger than indoor light and adequate for our eye spheres. Staying indoors? Ensure sufficient artificial lighting. Secondly, opt for a workspace with a window view, as you can benefit from daylight without stepping outside. Also, take regular breaks to gaze out the window for at least 20 seconds every 20 minutes; it relaxes your eyes and provides light exposure. Do you struggle to wake without an alarm clock? Consider using a light-based alarm clock. This allows your body to awaken naturally from deep sleep without being startled of the jarring sound of a traditional alarm." And thirdly, install extra light during the day if you are not able to be close to a window with natural daylight. You should at least get a light intensity of 400 lux in your eyes during the whole day, and less than 10 in the evening. What's the goal of The Good Light Group foundation? "To raise awareness about the impact of light. I believe it should be integrated into every wellness program because it's as important as healthy eating, exercise, and relaxation. Plus, getting enough light requires less effort than hitting the gym, doesn't it? So, go for it!” Original Dutch tekst by: Djaydee Kraus Watch the masterclass (in Dutch)

Health coaches play a big role in advising people about a healthier lifestyles. Their advice often includes these two essentials: a balanced diet and regular exercise. These are indeed cornerstones of good health, influencing everything from physical fitness to mental well-being. However, two crucial elements of a healthier lifestyle go unnoticed or are, wrongly, undervalued by health coaches. Photo by Jacopo Maia on Unsplash The power of daylight Daylight is more than just a cue for our daily routines; it's vital for our physical and psychological health. Exposure to natural light, or as we call it ‘good light’, during the day helps regulate our circadian rhythms, the internal process that manages our sleep-wake cycle. This regulation is essential not just for, here it comes, a high quality of sleep but also for mood, energy, well-being and to reduce the risk of conditions like seasonal affective disorder (SAD). And we didn’t even talk about vitamin D! Sleep Sleep, the other often-overlooked aspect of health, is fundamental to our well-being. It's the body's time to repair, regenerate, and reset. Quality sleep contributes to a lot of health benefits! It's during sleep that the body undertakes essential processes such as clearing out toxins from the brain, repairing cells, and consolidating memories. Chronic sleep deprivation is linked to an increased risk of numerous conditions, including cardiovascular disease, diabetes, and depression. Furthermore, inadequate sleep can impair cognitive functions, reduce physical performance, and diminish the body's ability to fight infections. So to all health coaches, don’t forget the fundamental roles of daylight exposure and sleep! And if daylight is not possible, it’s possible that adequate electric light compensates for the lack of daylight to a large extend.

Last week marked the annual council meeting which is also the 18th Good Light Group meeting! At every council meeting, we discuss our achievements so far and the future plans of our group. Please see the overview of the meeting below. You can watch all five parts of the meeting here: Opening, agenda and review 2023 Financials 2023-2024 Plan 2024 Socio-economic impact and Lighting Designer Guide Health, Well-being and HRM community & Alliance and Lobby

When we think about dangers in the office, we often worry about immediate and visible hazards, such as fires, which result in clear protocols and substantial insurance claims in the aftermath of such events. However, there are other dangers in the office that might not be immediately noticeable but can still harm our health over time. Insufficient lighting, poor air quality, and improper desk setups can lead to problems such as difficulty sleeping, increased illness, or headaches. Photo by Damir Kopezhanov on Unsplash For instance, inadequate lighting can strain our eyes and disrupt our body clocks, making it hard to get a good night’s sleep—and good sleep is essential for our well-being! Poor air quality in the office can lead to breathing difficulties, reduced focus, and feeling sick. These issues are often symptoms of "sick buildings," which lack clean air, proper lighting, or comfortable arrangements, though we might not notice these problems until they affect our health. People who work in ‘sick buildings’ are able to make insurance claims if they become ill due to poor air quality and incorrect temperatures, but what about light which is equally important. Currently, many building owners do not implement changes until they are required to do so. If workers could voice their concerns about becoming ill because of the building, it would encourage owners to pay more attention to the building's health. Ensuring our offices have clean air, sufficient light, and proper setups is crucial. It can make everyone healthier and happier at work and save the business money on sick leave.

When the sun comes out on a cloudy day, it often makes people happy. This isn't just a coincidence; it's the profound impact that natural light has on our mood and mental state. But did you know that sunlight can also spark a surge in creativity? Sunlight plays a crucial role in regulating our biological rhythms, and when in sync, it uplifts our mood, well-being, and happiness. This improved mood can open the doors to enhanced creativity. If you wish to bring good light into your life, watch our latest animations, click here: Try | Home | Good Light Group | Foundation Good light supports us in everything we do. Good light has a great positive impact on our experience of energy, sleep, happiness and health.

Bright light can make us feel immediately more alert and focused. Exposure to sufficient bright light during the day makes you feel more productive, focused and energetic. Go for a walk, sit within one meter of a window when inside and use artificial light that mimics daylight. If you wish to bring good light into your life, watch our latest animations, click here: Try | Home | Good Light Group | Foundation Good light supports us in everything we do. Good light has a great positive impact on our experience of energy, sleep, happiness and health.