Updated: Aug 19, 2020
This blog reviews four basic ways in which artificial lighting affects the health and well-being of growing eyes and brains - and concludes with a broader point - the impact of these factors on mental health.
The first issue is that of circadian rhythms and the key role of light in setting up this vital system correctly. Exposure to screens and some kinds of artificial light at the wrong time of day means that our kids’ growing brains and bodies are in permanent ‘jet lag’. A growing body of research is showing the extent of the harm that this can cause - from obesity to depression, learning difficulties and disruptive behaviour.
The second is that of of flicker - the rapid pulses of light generated by LED lamps, particularly when dimmed or powered with poor quality or incompatible components. This invisible flicker produces an ongoing and exhausting hypervigilant state, particularly for sensitive children and adults. The impact of flicker on the growing brain is only just being understood - but we do know that painful headaches and photosensitivity are triggered by this mechanism, with long-lasting impact on mental and physical health.
The third area to consider is light and contrast. Our eyes evolved to adjust to the overall light level across the scene rather than a single glowing point in the middle of a dark scene. The pupil is a essentially aperture, opening and closing to respond to that light level. When the difference is too great, it flips between ‘light’ and ‘dark’ settings, causing a range of painful symptoms known as ‘computer vision’ - from headaches, blurred vision and watery eyes to muscle fatigue. Adjusting to the bright screen, the pupil can dilate or open, allowing harmful wavelengths to reach the delicate light-sensing issue at the back of the eye. The protective pigments are still developing in the childs’ eye, exacerbating the issue and causing long-lasting damage.
Children get so used to seeing this way that it seems ‘normal’ and don’t raise the alarm. Around 25% of children don’t receive early diagnosis for other eye problems with damaging long-term implications.
So it’s important to balance light in the space - to eliminate reflection and glare from windows and overhead lights. And to work together - if you or your child are peering at a glowing screen because you've been so gripped by the film you're watching that you simply didn't notice the sun going down, switch on a warm low-level lamp and bring the balance back into the space.
The fourth point to consider is the need for bright light, so that the critical dopamine pathways which manage the way the eye is growing are triggered in the correct way. Like little seedlings, the eye is, literally shaped, by the levels of light it is exposed to.
As you can see from this diagram, the light you might get in a regular living room or in an office or supermarket is up to thousands of times dimmer than the light that you would get from being outside. All the myopia experts suggest that you need to be out for at least two hours a day. Ideally choose your exposure in the morning where that brightness is optimal.
And the final topic integrates these dimensions to the broader topic of light and mood. The impact of light can broadly be divided into visual and the non visual effects. The visual pathway gives rise images and our experience of an interesting and lively environment. As we have seen, light also generates a powerful cascade of powerful non-visual effects - the vital cycle that regulates everything from digestion to attention, mood and muscle strength. Beyond the dangers of light, I would like to encourage you to invite your children to be aware of how extraordinary light is.
A torch or a bike light against a wall can create magical shadows and tell stories, provide the starting point for photographs and moving images videos - and anyone who has ever played with a torch will know just how much fun that can be.
Experimenting with shadows in the sunshine outside is another wonderful game to play. A drinking glass or prism on a windowsill will create rainbows and an object with different facets will break up the image of the scene behind it in unexpected ways.
Placing candles on the table for your evening meal will create a memorable experience of ritual and celebration.
Light can be a source of endless wonder as these young people become curious observers, conducting their own experiments to learn what the world is like for themselves.
To end this conversation, I wanted to run through some simple tips for selecting lights as it can be incredibly confusing. So I have put together some basic tips below -
Cap/fitting – the code shows the size and type
Brightness - as a general rule, an LED is ten times brighter than the equivalent incandescent-
Spectrum – The lower the number, the warmer the color. That number relates to its energetic values, that is the Kelvin value. So a general warm white in your home is going to be about 3000 to 2700. A cool white is above 4,000. .
Colour Rendering Index. The colors that we perceive is a combination of the colors that are that come out of the light source and the colors that are reflected in the source. So if you think of something being green, actually what's happening is all the wavelengths except green, have been absorbed by that object. So you're looking for something which is at least color rendering index 90%. That means that at least 90% of the spectrum is present may not be in the same balances and daylight.
Lux. In areas where you're trying to concentrate or stay awake or be focused on the surface, seek out a bright, cool white source from a good-quality manufacturer. Like dress sizes, the numbers on the label are only a rough guide - it's worth trying them out in situ.
I hope I have inspired you to see the power of light to change your life for good. Beyond the physical and mental dimensions of this remarkable material, it is a kind of everyday magic and constant source of wonder and delight.