The right light, at the right time. What does “good light” really mean?

In this insightful video, Marijke Gordijn explains why lighting is much more than simply making a space brighter or changing the colour temperature.

Our biological clock relies on the light–dark cycle to stay synchronized with the environment. Yet, modern indoor environments often give us too little light during the day and too much light in the evening — potentially affecting sleep, alertness, performance, and overall well-being.

A few key takeaways from Marijke:
🔹 Timing matters. Morning light can help advance our biological rhythms, while evening light can delay them.
🔹 Intensity matters. Simply making indoor lighting warmer or cooler isn’t enough to support our circadian system.
🔹 Spectrum matters. We need to look beyond correlated colour temperature and consider measures such as melanopic EDI.
🔹 Daylight is powerful. Spending time outdoors during the day can provide the strong light exposure our biological clock needs.
🔹 Good lighting design is holistic. Intensity, spectrum, contrast, flicker, visual comfort, and even naturalistic changes such as movement and shadows can all contribute to a better environment.

This is especially important in offices, healthcare and care centres, where people may spend most — or even all — of their day indoors.

As Marijke puts it: we need the right light at the right time.