Happier with Light podcast with Jan Denneman, Chairman of the Board of the Good Light Group

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: most of us think about light only in terms of what we can see. If we can read, work or move around comfortably indoors, we assume the lighting is fine. But that is where the problem begins. Our eyes can perform perfectly well under dim conditions, even when it’s almost dark, while our brains actually need much more light during the day to stay alert, balanced and healthy.

Inside our eyes are special light-sensitive cells, the spheres, that send signals not just to the visual part of the brain but also to our internal biological clock and to areas that affect our mood and energy. These cells act as an inner sundial, constantly telling the brain what time of day it is. Based on that information, our brain adjusts hormone levels, deciding when we should feel awake and when it’s time to wind down.

The trouble is that indoor light levels are usually far too low, leaving this inner sundial without proper guidance. As a result, many people suffer from sleep problems, low energy and poor concentration. The solution, however, is surprisingly simple. Spend at least two hours a day outdoors, ideally with half an hour in the morning light. When that isn’t possible, sit near a window or use modern LED lighting that mimics natural daylight.

Throughout the day, our eyes need at least 500 lux of light to stay in sync with our biological rhythms. Yet most indoor spaces provide only 50 to 100 lux, which is far too little. If we truly want to support human health and wellbeing, we need to rethink how we illuminate our homes, offices and schools. Setting lighting standards to deliver at least 500 lux at eye level would make a real difference. It would allow even those who spend most of their time indoors to experience the benefits of good light — light that not only helps us see, but helps us to live a healthier, better life.

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