Does reading in dim light cause vision problems

If you were ever caught reading in low light or using a flashlight under the bedcovers to read after lights-out, your parents might well have warned you that straining your eyes would damage your eyesight. Or perhaps you used to hear that it’s easy to spot the studious children at school because they were the ones who had spent so long with their heads in a book that they had to wear glasses.

Whatever you heard, the warning that people shouldn’t read regularly in dim light is a familiar one. While permanent damage to our eyes cannot be caused by reading in the dark, it can lead to short-term effects which are completely avoidable – such as headaches and eye strain. 

Let’s look at the basics first. Short-sightedness or myopia means that a person can easily see things that are close up, but objects in the distance such as the number on a bus or the menu board in a restaurant look blurry. Wearing glasses or contact lenses solves the problem, but it doesn’t answer the question of why some people develop short-sightedness in childhood while others don’t. 

Our eyes are cleverly designed to adjust to different light levels. If you are trying to read in the gloom your pupils dilate in order to take in more light through the lens onto your retinas. Cells in your retina, called rods and cones, use this light to provide information to the brain about what you can see. If you are in a dark room, for instance, when you just wake up, this process allows you to become gradually accustomed to what initially feels like pitch-black darkness. If you switch a light on, it feels unbearably bright until your pupils have had time to readjust once more.

The same happens if you strain to read a book in dim light. Your eyes do adjust, but some people find the strain gives them a headache. Likewise, when you look at something close-up like a book or some sewing, the eye adjusts, and muscles lengthen the area known as the vitreous chamber – the gelatinous bulk of the eyeball that lies between the lens and the retina.

With that in mind, here are a few reading environment tips to take into consideration for children and yourself.

  • Be mindful of the brightness of your digital screen vs. your reading environment. As many books are now switching from paperback to digital – including student textbooks – it’s important to remember that the lighting of the area you’re reading in should be as bright or brighter than your digital device. Therefore, avoid reading in dark rooms. Reading from digital devices in a dark room can cause discomfort, leading to lower concentration and disorientation because your eyes are constantly adjusting between the brightness of a screen and your dimly lit surroundings. Additionally, dark rooms will not provide sufficient lighting if you’re reading a paperback book.
  • Increase task lighting in your home. Task lighting refers to artificial light that increases illuminance for activities, such as reading. Most households are significantly under-lit,  says Graham Strong from the University of Waterloo’s School of Optometry, which can cause your eyes to tire out much quicker. For tasks such as reading, the light should be positioned to shine directly onto the page and not over your shoulder to avoid any glare
  • Playing outside seems to be beneficial to the eyes and perhaps young children should study in good light to avoid straining their eyes. As for adults, all these studies were conducted on children whose eyes were still developing, so if you still want to read under the covers by torchlight then it’s unlikely to cause you any problems. Of course, now that you’re old enough to decide your own bedtime, you probably don’t need to.

To ensure your child’s eyes are kept in good health for reading and other developmental activities, make sure to book regular eye appointments with your optometrist.

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