Harmful Effects of Reading or Writing under Dim Light

Remember the time when your parents used to tell you to read when it’s daylight or to turn on the light when reading your favorite Harry Potter sequel?! Yes, we’ve all been there more or less… Their argument was that reading under dim light may result in myopia or nearsightedness.

Is this true or is it actually a myth? Can writing or reading in the dark really damage our eyesight?

Human eye; image source: pexels.com

The Science behind Reading or Writing under Dim Light

When we read in the dark, our pupils dilate do absorb more light. Also, your eye muscles relax, you produce more photo-sensitive chemicals, and your eyes become wide open. That is why our eyes hurt when someone suddenly turns on the light. Some people are prone to headaches due to eye strain and poor light per se is not the one to blame for eyesight problems.

The leading factor for temporary short-sightedness (myopia) is what scientists call “close work.” People who spend most of the day working on their computers, reading or writing, might develop the myopia-like condition.

It means that they see objects closer to them clearly but have difficulties with recognizing a person across the street or identifying a traffic sign, for example. When you do close work under low light, your brain gets mixed signals—relax the muscles to absorb more light. NO! Focus on the image in front of you. This is the mechanism that causes eye strain. However, after your eyes rest, your eyesight should go back to normal.

Another reason for fatigue is eye dryness. However, this also does not happen because of dim light. When we are focused on reading or writing, we tend to blink less which makes our eyes dry which is uncomfortable. This problem can easily be solved by, well, by blinking once in a while.

How to Prevent Eye Fatigue

If you tend to read or write under dim light there are certain guidelines you should follow to prevent eye fatigue:

  • Position the lamp to light the book directly
  • Remember to blink
  • Occasionally, focus on a distant object
  • If your eyes are red, use eye drops
  • If you read on your phone or tablet adjust the brightness of the screen and contrast
  • Take a break

The Verdict

Experts claim that reading or writing under dim light will not permanently damage your eyesight. However, it can cause a temporary condition similar to myopia that goes away after your eyes rest.

The mechanism behind this problem is the fact that our brain gets confused by the fact that pupils have to dilate to absorb more light, and at the same time to stay focused on the image in front of us.

Also, close work causes eye dryness which can worsen the eye fatigue. What we can do to prevent this benign but unpleasant condition is to rest, focus on a distant object every once in a while, and blink. If myopia does not go away, visit your eye doctor because it can indicate that you suffer from some underlying condition.


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