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a blog by our science advisor Mariana Figueiro Circadian rhythms are internal recurring cycles that find expression in a multitude of physiological, psychological, and behavioral processes across myriad animal and plant species. The master clock that generates these circadian rhythms would otherwise free-run at a natural period that is slightly longer than the solar day, and external environmental cues maintain synchrony—or entrainment—between the master clock and the time of day at our local position on Earth. The master clock’s primary environmental entrainment cue is the 24-hour pattern of light and dark incident on the retinae that is associated with Earth’s axial rotation. The circadian system sends an alerting signal throughout the body during the day and sleep signal at night in all diurnal animal species, predominantly through the regulation of hormones. The cyclical rise in melatonin levels in the hours preceding bedtime, for example, triggers the onset of sleep. Conversely, the rise in cortisol levels in the hours before waking informs the body of the night–day transition from inactivity to activity. In an entrained individual, these two signals or processes work in a homeostatic relationship that balances daytime alertness with consolidated nighttime sleep. Misalignment of this relationship through inadequate or poorly timed circadian-effective light exposures is strongly associated with risks for various major diseases, declines in performance, and sleep and mood disorders. These risks demonstrate a clear need for applications that promote circadian health in an indoor built environment where lighting has typically been specified to benefit the human visual system rather than the circadian system. This four-week, within-subjects, crossover design field study investigated the effectiveness of electrochromic (EC) glass windows on measures of circadian phase, sleep, vitality, and mental health in a residential environment. (EC glass changes from clear to tinted via the application of low-voltage electric current to a thin electrochromic coating embedded within its layers, reducing glare and thermal discomfort but not the penetration of circadian-effective light.) The study’s 20 participants were healthy office workers (median age of 33 years) who spent most of their time working at home due to restrictions associated with the COVID-19 pandemic. They experienced two experimental conditions (separated by a six-day washout period) in randomized order: (1) one eight-day intervention period with functionally standard (i.e., clear) windows with blinds partially drawn and (2) one eight-day intervention period with functioning EC glass windows. We hypothesized that compared to baseline measures, the EC glass condition would increase participants’ access to daylight and thereby lead to stronger alignment of rest-activity patterns with the day–night cycle and improved objective and subjective sleep and mental health outcomes. We found that the study’s participants showed greater circadian alignment (as shown by the consistent dim light melatonin onset times), earlier and more regular sleep times, and improved vitality and mental health when living in an apartment fitted with the EC glass compared to traditional glass windows and blinds. In sum, the study confirmed that architectural designs effectively and comfortably incorporating daylight can yield tangible benefits for daytime office workers, even when working from home. Short Summary: Circadian system disruption from inadequate or poorly timed light exposures is strongly associated with risks for various major diseases, declines in performance, and mood disorders. Our study found that electrochromic glass windows that reduce glare and thermal discomfort but still permit the penetration of circadian-effective light promoted circadian system alignment, earlier and more regular sleep times, and improved vitality and mental health. Publication link https://www.mdpi.com/1660-4601/18/19/9980

We got together online for the eleventh Good Light Group meeting on Tuesday the 28th of June. In these meetings we always let a couple of participants talk about their business or new research. This meeting: Renske Lok of the Stanford University and our Science Advisor talked about the impact of daytime illuminance on cognitive functioning and alertness. Merijn Wegdam the founder of Sunshower talked about ‘low dose UV for healthy vitamin D level in wintertime’. #1 Renske Lok, her presentation was about the effect of light on subjective alertness, mental performance and how these depend on homeostatic sleep pressure and the circadian clock. She talked about the alerting effects of light occur during the night and how we can improve daytime alertness. You can watch her presentation here #2 Merijn Wegdam, his presentation was about ‘Low dose UV for healthy vitamin D level in wintertime’ he talked about the fact that in the wintertime the sun is not powerful enough for health benefits, so Sunshower combined sunlight with the daily shower. They developed a light that is waterproof and provides the user with just enough UVB to maintain a healthy vitamin D level in wintertime. You can watch his presentation here

Mushfiqul Anwar Siraji won one of the student travel awards sponsored by the Good Light Group! This prize was awarded at the 33rd meeting of our partner the Society for Light Treatment and Biological Rhythms in June 2022. He won the award for his work on the development of a Light Exposure Behaviour Assessment. The development of the Light Exposure Behaviour Assessment is an international collaborative project where Mushfiqul worked closely with Rafael Lazar under the guidance of Manuel Spitschan PhD and others. The instrument captures light exposure-related behaviour and is psychometrically validated. The behaviour is divided in five acknowledged light exposure-related behaviour dimensions. If you want to know more, watch his talk or go to the LEBA website. Watch his talk here: https://lnkd.in/ekxjbCjj download LEBA: http://leba-instrument.org (preprint coming soon)

The 33rd SLTBR Annual Meeting will be in Manchester this year. From the 23rd till the 25th of June. The program committee of SLTBR is preparing an excellent program with three symposia dedicated to fundamental, applied and clinical new insights. The CME course will be filled with lectures on the current status of the use of melatonin. In addition, they will organize a young scientists symposium, a poster session with wine & cheese, and, of course, a banquet. Our board member and president of the SLTBR Marijke Gordijn is part of the team who organises this meeting. More information about the event here

There is a range of different Good Light lamps from a lot of different brands. On our website we highlight some of these different lamps! Because working from home has become the new normal for many of us. People are investing in home workspace ergonomics to make their offices more comfortable, but the main question is how to make our home offices healthier. BrainLit Alven, a personal, connected, and free-standing BioCentric Lighting™ system emitting simulated daylight indoors to support your health and well-being. Through its BioCentric Lighting system™, BrainLit Alven mimics the most important aspects of daylight to maintain your natural circadian rhythm. Learn more about the BrainLit Alven

Our board member Jan Denneman will present this free webinar on the 23rd of June at 16.00 CEST. This webinar will explain how light influences your body and how you can optimize your light for a year-round spring feeling. People need to start recognizing the symptoms of being shielded from daylight: poor sleep quality, little energy during daytime and mood swings and relate these symptoms to the lack of light. Then, you can start acting. Examples illustrate how this works for sleep, Alzheimer patients, summertime, and winter blues. Jan will explain how to bring good light into your life according to a three-step approach. If you’re not a member of the learning platform of Signify you can register. you will find all relevant educational resources which are not publicly available. Date of webinar -Jun 23, 2022 Time of the webinar - 4:00 PM CEST Presenter - Jan Denneman Register here

Tone Henriksen is Science Advisor of the Good Light Group, and co-author of the scientific article on the effect of blue-blocking glasses on melatonin onset during pregnancy. All life is adapted to the natural light-dark cycle produced by the 24-hour rotation of the earth. Even before we are born, we get a time-cue from the outer environment from our mother’s night hormone melatonin. Melatonin passes freely over the placenta and seems to be important for a healthy pregnancy in several ways. The hormone of darkness plays an important role for the placenta – the organ securing oxygen and nutrition to the fetus. Melatonin is a strong free radical scavenger and has neuroprotective function for the growing fetus. Nevertheless, melatonin protection is not part of the general advice to pregnant women – yet. Recent evidence suggests a simple way of protecting pregnant women and fetus from melatonin shortage, without the need to stay in real darkness. As it turns out, all light is not equal when it comes to suppressing the darkness hormone melatonin. To the brain-, light containing high portions of blue frequencies is interpreted as daylight. Natural morning and mid-day sunlight have a high portion of blue. In 2014, Shuji Nakamura won the Nobel Prize in Physics for inventing blue emitting LED diodes-, which was necessary for making white and bright indoor lighting, similar to sunlight. However, in the natural condition, the sun sets in the evening. Image a camping bon-fire, far away from electric lighting. No blue light there, and melatonin production in the brain starts fine-tuned and synchronized to the internal circadian rhythm and natural environment. This is a nice scenario but, except during holidays, hardly a practical advice to pregnant women. Could blue-blocking (BB) glasses work as well? Randi Liset and co-authors in Bergen, Norway, conducted the first trial testing the melatonin protective effects of amber glasses (99% blue-blocking) as compared to grey control glasses (approximately 50% blue-blocking) for healthy pregnant women in the third trimester (N=60) A randomized controlled trial on the effects of blue-blocking glasses compared to partial blue-blockers on sleep outcomes in the third trimester of pregnancy - PMC (nih.gov) Both groups wore the glasses for three hours prior to their preferred bedtime. After two weeks, the BB-glasses group had 43 minutes earlier melatonin onset and the control group 11 minutes earlier melatonin onset than at baseline. The adjusted difference of 28 minutes was highly significant. The superiority of the near 100% blue-blocking over the partially blue-blocking control condition was clear. This shows the need for blocking as much blue light as possible in the evening for optimal protection of the rise of your melatonin. These glasses seem an easy way to effectively lower melanopic lux levels in the evening. Other studies have shown that more daylight during the daytime increases the capacity of producing melatonin the following night. Follow-up studies combining daytime light exposure and evening blue-blocking are wanted. For now, this novel study by Liset et al. provided the first evidence that BB-glasses worn in the evening for three hours before bedtime can serve as a simple, low-cost and safe means of non-pharmacological strengthening of circadian health for mother and fetus.

Our board member Marijke Gordijn was asked to give a presentation about nightlife from different perspectives for the Nature Bits program. A nature education group which organized a camping trip on Texel, an island of the Netherlands, to watch the milky way and learn about the effects of light and darkness on nightlife and humans. The right light at the right time In the vlog you see what Marijke means with the right light at the right time, or how we call it ‘Good Light’. Want to know more about good light? Read our other news blogs, for example: Why do we sleep so late Nature bit is a program for people between 18 and 30 that want to be actively involved in a greener and more sustainable future. How? To learn as much as possible about nature and share this knowledge with other people. Watch the vlog here Nature Bits

All lectures are now online, so if you missed it, you can now enjoy listening to the three different topics and learn more about light. In the free webinar deLIGHTed talks several lighting experts talk about various aspects of what light does to our health. In cooperation with the Daylight Academy, Society of Light Treatment and Biological Rhythms, International Association of Lighting Designers, Luger Research we organize the deLIGHTed talks webinars. Four light professionals were invited to talk about Healthy Lighting Recommendations, Bright days, Dark nights and to lead the panel discussion. You can now watch the lectures online here: Dr. Luc Schlangen - Introduction on Healthy Lighting Recommendations He will give a brief introduction on a recently published set of recommendations for bright days, dim nights and indoor light exposures to best support human physiology, sleep and wakefulness in day-active people. Watch the lecture Dr. Christine Blume - Bright Days Beyond sleep, daylight has repeatedly been shown to have beneficial effects on mood. In her talk, Dr. Blume will outline the scientific basis of her recommendation, that the foundation for good sleep is laid during the day - with adequate exposure to daylight. Watch the lecture Koosje Lamers, MSc. - Dark Nights During this presentation, we will explore the importance of dark nights, and the implications of light pollution for our own wellbeing, cultural history, and our natural environment. We will touch on solutions and discuss how initiatives like the Darkness of the Wadden project can combine fighting light pollution with sustainable development. Watch the lecture Curious about the panel discussion? Carla Wilkins together with the other experts answer a lot of questions from the attendees. Watch the panel discussion here More information about the experts or lectures here

Oliver Stefani, Participant of the Good Light Group, analysed and summarized a new scientific article on predicting melatonin suppression. Variations in light conditions, both in terms of intensity and spectrum, are an important determinant of non-visual effects of light on people. Light is the principal synchronizer (i.e. Zeitgeber) of human circadian rhythms. Light exposure during the biological night can lead to sleep and circadian rhythms disturbances. In particular in the evening and at night, light with a high proportion of short wavelengths in the blue spectral range suppresses the secretion of the hormone melatonin. This hormone is naturally produced during the biological night and supports darkness related behaviour. The onset of melatonin production (in dim light) is a marker of the circadian rhythm in humans. To support good health and sleep, the evening increase in the body's own hormone melatonin should be attenuated as little as possible. But how do we define little, and how long can this exposure last? What plays a bigger role: timing, duration, brightness or spectral composition of the light? The latest publication in J Pineal Research provides a first set of insights for answering this riddle. The authors used machine learning to analyze light-induced melatonin suppression data from 29 peer-reviewed publications. The suppression of melatonin was primarily dominated by the spectral composition of the light exposure which defines the quantity melanopic EDI. The CIE uses this quantity in its recommendations on proper light at the proper time for Integrative and Human Centric Lighting applications. An exact dose, however, was not yet provided in the CIE recommendations. The authors used a logistic model to predict the melatonin suppression response based on various characteristics of the light exposure (duration, spectral composition, pupil dilator usage etc.). The model predicts that for light exposure durations of 0.5, 1, 2, 3 and 4 hours, nocturnal melatonin secretion is reduced by 50% when the light exposure has a melanopic EDI of 600, 350, 120, 43 and 15 lx, respectively. This confirms and extends insights on the metric melanopic EDI being an important predictor of biological effects of light within integrative (human-centric) lighting applications. As a metaphor, one could compare the melanopic EDI of our light environment to the caffeine content of a drink: a small espresso or a big cup of normal coffee provide the same dose of caffeine. The publication and a small toolbox (see Supporting Information) can help lighting practitioners to better estimate the effect of light exposure on melatonin suppression. The publication, the toolbox and a video about it can be found in the Journal of Pineal Research here: https://onlinelibrary.wiley.com/doi/full/10.1111/jpi.12786

Independent research has shown systemic health benefits of the Seaborough technology SunLED This means: near-infrared light that shines on your face and neck, results in whole-body effects including lowered resting heart rate, better mood, and boosted immune system. The principal investigator Marijke Gordijn from Chrono@Work B.V. / University of Groningen will tell you everything about the study in our webinar on June 7, 3 pm (CEST). Join the webinar, to learn more about: - How the study was organized - What the results are - How strong the evidence is Subscribe for free at Seaborough

Since the first quarter of 2022, the Good Light Group introduced the concept of Science Advisors. Next to the existing Participants and Partners they are supporting the Good Light Group. Their role is to ensure that the information, claims and guides are based on scientific arguments. The Good Light Group has already 20 Science Advisors in various fields of expertise such as chronobiology, light and health, sleep, neuroscience, psychiatry, and medicine. The multidisciplinary input will support the Good Light Group in bringing a complete story on the importance of good light and the impact of light on people. The outreach to individual scientists to join as Science Advisors proved to be a very practical way to involve many scientists in the work of the Good Light Group. For the latest update on the Science Advisors, see the dedicated webpage: https://www.goodlightgroup.org/science-advisors. Scientists who would like to join as Science Advisor can contact info@goodlightgroup.org for more information.