We've heard before from a parent, a grandparent or a very concerned auntie peering over their shoulder at bedtime: "Put the light on or you'll ruin your eyes!"
Science, however, has been quietly undermining this piece of household wisdom for decades.
Does reading in dim light actually cause lasting damage to your eyesight?
Verdict:
FALSE, but...
The idea that reading in poor light ruins eyesight is one of the most enduring health myths around, debunked in a study published in the British Medical Journal in 2007 and repeatedly confirmed by researchers since.
There is no scientific evidence that reading in dim light causes permanent damage to the eyes. However, it does make the eyes work harder.
When light levels drop, the pupils dilate to let in as much light as possible and the muscles controlling the lens have to strain to keep text in focus.
The light-sensitive rod cells at the back of the eye, which handle low-light vision but are not designed for reading fine detail, are also pressed into service.
The result is eye strain, which can cause tired eyes, headaches, difficulty focusing and temporary dryness from blinking less often while concentrating.
These symptoms are real and uncomfortable but they are also temporary, resolving once the eyes are rested.
An ophthalmologist from the Cleveland Clinic told WebMD that there is no scientific evidence reading in the dark causes any long-term harm to the eyes and that any discomfort does not damage the structure or function of the eye.
So much for the bedtime lecture.
However, the picture is more complicated when it comes to myopia, or short-sightedness, which is a genuine and growing concern in Malaysia and across Asia.
A 2020 literature review published in the journal BMC Ophthalmology, which examined 80 studies on myopia in schoolchildren worldwide, identified dim light exposure as one of several risk factors for myopia development and progression in children, alongside low outdoor time and extended near work.
Myopia prevalence in Asia is significantly higher than in other parts of the world, with rates of around 60% in children across the region compared with around 40% in Europe.
Malaysia is no exception, with studies including the Malaysia Refractive Error Study in Children finding myopia rates of around 31% in Malaysian Chinese children aged seven to nine.
Researchers believe the protective effect of bright outdoor light, particularly sunlight, plays a significant role in preventing myopia in children, likely through the stimulation of retinal dopamine.
A 2026 study from the SUNY College of Optometry, published ahead of print and reported by ScienceDaily, proposed that sustained close-up focus in dim indoor light reduced the amount of light reaching the retina in a way that could contribute to myopia progression.
The researchers were careful to note that the study offered a hypothesis requiring further investigation rather than a definitive conclusion.
The broader consensus among researchers remains that time spent outdoors in natural light is one of the most well-supported protective factors against myopia in children.
For adults, the advice is simpler: dim light will not damage the eyes, but it will make them tired.
A well-lit reading environment is still recommended by eye care professionals, not because poor light causes harm but because it makes reading more comfortable and sustainable.
Sources:
1. https://pmc.ncbi.nlm.nih.gov/
2. https://pmc.ncbi.nlm.nih.gov/
3. https://pmc.ncbi.nlm.nih.gov/
4. https://pmc.ncbi.nlm.nih.gov/
5. https://www.webmd.com/eye-
6. https://www.sciencedaily.com/
