Is reading in dim lighting bad for you?

Shutterstock.com/ Francisco Javier Diaz

Usually, we would not tell you to listen to this website more than your doctor but on this occasion, it may be a good idea. A recent study was released on the seven myths that doctors are most likely to believe by the British Medical Association. It showed that there are many things that doctors believe in science that they advise their patients on, that are simply not true.

The most common thing reported, that is almost universally believed, is that reading in dim light is worse for your eyesight. While many of us believe this and can likely remember our parents telling us this at bedtime, there is no proof it is true. Whether our parents simply wanted us to go to sleep early or really believed it, we will never know. 

Staring at objects that are close for too long is proven to cause eyestrain. This eyestrain has been linked with the development of myopia (the most common condition that causes bad eyesight, also known as nearsightedness). Staring at a book in dim light will cause additional eye strain as well, however, there is no proof that this leads to accelerated myopia. To date, all studies suggest that simply resting your eyes will recover any additional strain placed on the eyes compared to normal reading. 

In one way, this makes sense. People have been reading under dim lighting for years as before there was electricity people would often read by candlelight. Today in a world where light sources are more easily achieved we are actually seeing instances of myopia going up (clearly because we are staring at our phones and computers more).

In another way, it doesn’t make a lot of sense. If staring at something causes a strain on the eyes, and if straining the eyes causes bad eyesight, then it seems pretty straight forward to assume that something that strains your eyes more is worse for your eyesight. While no studies have proven this to date it may be a case of obeying common sense before obeying the scientific results that will likely arrive at a later date. 

It is still not even understood why exactly staring at things close up results in bad eyesight either. The current theory that leads the way is that staring at these things for too long stretches the eyeball and over the years this stretch becomes permanent causing someone to develop myopia as they age. When someone does this under dim lighting, their eyeball is being stretched the same amount, it is just that their iris is working extra hard to let more light in and focus on the dimly lit words on a page. This extra work on the iris has not been linked to deteriorating eyesight so it appears if you enjoy reading by dim light you can continue. However, as the original cause is still unclear while reading we recommend resting your eyes whenever they feel overstrained.

As a general rule, in dim or normal light, optometrists recommend taking a break from focusing your eyes on up-close things for 2 minutes in every 30-minute window. If you can you should close your eyes as well because while reading it has been shown that people blink ¼ of the time that they do usually. This causes the eyes to dry out a little too much and closing the eyes will allow them to moisten and be more comfortable.

It appears the jury is still out on whether reading under dim light is bad for your eyes. While there is no proof that it is bad for you, common sense would suggest it is certainly not good for you. With that in mind, we suggest avoiding straining your eyes whenever possible and taking plenty of reading breaks too.