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

We’ve organised our 24th Good Light Group meeting.   The topics included: 1. Jan Denneman - Good Light Group news 2. Lawrence Lin – Good Light Group Asia 3. Kevan Shaw – The aging eye Photo by Andres Sanz on Unsplash Missed the Good Light Group Meeting?   Watch the presentions online here:   Good Light Group news - Jan Denneman The aging eye -  Kevan Shaw

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

We are very happy to welcome it doens Lighting to our group! It does Lighting is an independent, qualified, and evidence-led company with nearly 40 years of experience. They get to the root of what light means and how it acts as nutrition for the body’s cells, and they are highly experienced in designing healthy lighting schemes. “I was pleased to accept the invitation to join the Good Light Group as a Scientific Advisor. The group brings together an international cohort of r

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

SunLED is a Dutch start-up at the forefront of near-infrared light research and its effects on human health and well-being. The near-infrared part of the sunlight spectrum is often missing from our indoor lives; however, it is essential for our bodies. Near-infrared light can penetrate deep into our skin and activate energy production in our cells. It has multiple proven health benefits for the human body, including:  Improved mental health - makes you feel more energized, fo

Launch of Good Light Group Asia We are very pleased that Lawrence and his team have taken the initiative to establish Good Light Group Asia. This organization is dedicated to promoting the use of good indoor light. Across Asia, we see a growing awareness of the impact that light and lighting have on health and well-being. This awareness can be seen within the lighting industry, academic institutions, and governments. This is highly relevant. Just like elsewhere in the world,

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

Effective January 1, 2026, Dave Hollingsbee and Roger Sexton have stepped down from the Board of the Good Light Group. We would like to sincerely thank them for their many years of dedication, support, and valuable contributions to our mission as Board members. Both will continue to support the Group in other capacities. Their commitment has helped significantly strengthen our impact and global reach. At the same time, we are pleased to welcome Ulysse Dormoy , CEO of Atrium ,

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

We’ve organised our 23nd Good Light Group meeting. The topics included: Marijke Gordijn  - Light for Public Health Initiative Conor Heaney  - Regulatory and Policy Dimensions of Light for Public Health Ulysse Dormay  – Light & Life, A circular Concept Photo by Artem Beliaikin on Unsplash Missed the Good Light Group Meeting? Watch the presentions online here:  Marijke Gordijn Conor Heaney Ulysse Dormay Want to contact Conor? Please email him at: conor.heaney@icloud.com

A blog by Timo Partonen From November to January, if your exposure to daylight is of 1 hour or longer per day, it is likely that you will not have depressive symptoms during that period of the year. Compared to the conditions where your exposure of less than 1 hour per day, the odds of having depressive symptoms will be 0.72 on average, yielding the confidence interval from 0.60 to 0.82. If you have children younger than 12 years of age at home, it is even more likely that yo

Every living organism on earth follows internal 24-hour cycles known as circadian rhythms. From a flower opening at dawn to a surge of human alertness in the mid-morning, these rhythms are deeply embedded in our biology. They regulate countless processes, from gene expression and metabolism to behaviour and sleep. In mammals, the central pacemaker of this system is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN synchronises peripheral clocks that ex

In this episode of the Happier with Light podcast, Lard talks with Jan Denneman, Chairman of the Good Light Group. Jan shares why the organisation was founded and how everything it does is based on science. More than thirty scientific advisors and experts in fields such as chronobiology, neurophysiology, sleep, psychiatry and light, support the group in shaping its message and grounding every insight in solid research. Jan reminds us of something that is often overlooked: mos

Light affects how we sleep, feel, and perform – yet public awareness of its impact remains limited. The Light for Public Health  initiative aims to make evidence-based knowledge on light and health both accessible and actionable, thus turning scientific insight into public benefit. “Light isn’t just for vision – it is a key signal for human biology,” says Manuel Spitschan, research group leader at the Max Planck Institute for Biological Cybernetics and professor at the Techni

With insights from IALD, WELL, DLA, and leading researchers, this webinar explores daylight-like conditions indoors and their impact on health, design, and circadian well-being. With an increasing evidence base that properties of daylight can positively affect people’s health and well-being, time has come to address the challenge of daylight-like conditions indoors. At present, many people spend time in spaces lit with electric lighting – at work places and in classrooms. How