Analysis: Too little daylight and too much artificial light are reshaping childhood health in ways we can no longer ignore
Myopia, or short-sightedness, is rising at an extraordinary pace. Experts predict that one in two people worldwide will be myopic by 2050. This isn’t just about the hassle of changing glasses prescriptions. Even a small increase in prescription raises the risk of serious eye problems later in life, including cataracts, glaucoma, and macular degeneration.
Parents often assume screens are to blame. While near work and digital devices do increase the risk of myopia development, the real story is more complex. Growing evidence shows that natural daylight is one of the most powerful protectors against myopia, and most children aren't getting enough of it. Startlingly, a UK survey found that 74% of children spend less time outdoors than prison inmates.
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From RTÉ Radio 1's Today with Claire Byrne, why children's eyesight is getting worse
How light shapes the eye
A landmark Australian study in 2008 showed that children who spent more time outdoors were less likely to develop myopia, regardless of family history or time spent reading or engaging in near activities. Since then, research worldwide has confirmed this protective effect.
The mechanism is rooted in eye growth. The longer an eye becomes, the more short-sighted the person will be, and the greater the risk of complications. Think of it like a balloon: the more it stretches, the thinner and weaker it becomes, making it prone to damage. Bright outdoor light stimulates dopamine release in the retina, which helps regulate eye growth.
The difference between natural outdoor light and indoor artificial light is stark. On a cloudy day, outdoor light measures 10,000 to 30,000 lux, and over 100,000 lux in bright sun. Even in the shade with a hat and sunglasses, daylight is 11 to 43 times brighter than indoors. By contrast, classrooms and bedrooms typically provide only 100–500 lux, which is far too dim to trigger protective effects.
What research tells us about outdoor light and myopia
Research suggests that at least two hours of outdoor time daily helps reduce myopia risk. Large school-based trials in Taiwan and China showed that simply adding outdoor class breaks reduced the number of children developing myopia. A Shanghai study using smartwatches recently revealed that as little as 15 minutes of bright daylight slowed eye growth. Other researchers have even trialled classrooms with glass walls in an effort to boost natural light indoors. The importance of daylight is also highlighted by groups like the Daylight Academy.
TU Dublin’s MOSAIC study found that the effectiveness of atropine eye drops, one of the main medical treatments for myopia, was reduced during Covid-19 lockdowns, when children were confined mainly indoors. This suggests that outdoor light doesn’t just minimise the risk of myopia developing, but it may also support existing treatments.
The knowledge gap about outdoor light
At the Centre for Eye Research Ireland, our Child Activity and Myopia study surveyed parents, teachers, and optometrists about lifestyle factors affecting children’s vision. We identified a clear knowledge gap: nearly two-thirds of parents were unaware that outdoor time helps protect against myopia.
Worryingly, most Irish children aren't hitting the recommended target of two hours per day. On school days, 80% fell short and almost half did not reach the target even at weekends. Meanwhile, screen use was high: more than half spent over an hour a day on devices during the week, rising to nearly 80% at weekends. One in 10 clocked up more than five hours on weekend days!
Drowning in artificial light
It's not only that children get too little daylight, we are also drowning in artificial light, much of it richer in blue wavelengths than ever before. Artificial light at night from streetlights, shopfronts, and especially the LED bulbs and devices that have replaced old incandescent lamps, is now a constant part of modern life.
Unlike the warmer, softer glow of incandescent bulbs, LEDs emit a cool, blue-rich light that disrupts circadian rhythms and interferes with sleep. For children, the effect is a double hit: too little natural daylight during the day, and too much artificial light at night. Both patterns carry consequences for vision, health, and wellbeing.
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From RTÉ Radio 1's Drivetime, when was the last time you checked your screentime?
For millennia, human life was tuned to sunrise and sunset, driving the rhythms of life across days and seasons. The light bulb changed that, and we are paying the price. Indoor lifestyles and 24/7 illumination have severed our connection to the natural rhythms our bodies depend on. Daylight is as vital to health as clean water or fresh air, and should be built into how we design homes, schools, and cities.
What we can do
Encouraging children to spend more time outdoors requires a team effort:
- Parents and families can help by aiming for the two-hour daily target, even in short bursts throughout the day.
- Teachers and schools can protect outdoor breaks, PE and create opportunities for outdoor learning, such as nature walks.
- Policymakers and politicians can help by ensuring neighbourhoods are child-friendly and safe for play, and by designing schools and public spaces with daylight in mind.
Looking after children's eyes is about more than glasses or drops. It’s about recognising the crucial role that daylight plays in healthy development and making outdoor time part of everyday life.
While screens are often in the spotlight, the real key may lie in something as simple as stepping outside. Because when it comes to protecting young eyes, it’s not just screens and daylight really matters.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
