It has been 60 years since the Cold Spring Harbour Symposium on biological clocks. More than 40 years ago, it was discovered that light has an impact on melatonin secretion in our body. And 20 years ago, the existence of retinal ganglion cells in the eye, the so-called ipRGCs and their link to melanopsin, was discovered.
Scientific consensus
There is a clear scientific consensus that as human beings we not only need light to see, but we also need light to function. This is called the difference between visual and non-visual effects of light.
However, most international standards nowadays are only geared to our visual needs and hardly take our non-visual needs into account. After all, light also serves as a zeitgeber, a pacemaker for our daily biorhythm, our 24-hour cycle. The lack of light therefore also disrupts that biorhythm. We often get too little light during the day and the use of tablets and smartphones, which often emit light similar to morning light, aggravates this situation.
However, there are already ways of measuring the non-visual impact of light and incorporating it into lighting plans. Traditionally, one speaks of lux at the workplace, but here one speaks of melanopic lux, measured at eye level.
More and more research is therefore being carried out into how these non-visual aspects can be taken into account when drawing up a lighting plan. It is becoming clear that the quantity but also the quality of light play an important role.
Daylight
The best light remains daylight, of course, and the first advice when it comes to the non-visual impact of light is to get enough daylight every day. A half-hour walk in the morning can do wonders here.
But there is also good news. The advent of new LED technology means that we can also generate artificial light indoors that not only varies in the amount of light but also spectrally.
But there is also good news. The advent of new LED technology means that we can also generate artificial light indoors that not only varies in the amount of light but also spectrally.
So there is already a lot of knowledge and we know with a great deal of certainty today that we need more light. In a subsequent article, I will summarise the best recommendations for putting this knowledge into practice.
This blog is a free summary of an article by Yves Dauvillers from Frontiers in Neurology, August 2021.
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