The main advantage of apps with a dark mode is that they don’t shine so brightly in our eyes late at night. But there’s a disadvantage, too: dark mode can actually be harder to read, and possibly contribute to eyestrain.
In this video from Cheddar, Dr. Sam Pierce of the American Optometric Association lays out the case against dark mode.
White text can also have a halo around it when it’s on a dark background. And in fact, white text on a black background can be too high contrast, contributing even further to the text being hard to read.
But regardless of the contrast, any dark mode is going to allow your pupils to dilate.
That’s exactly what our eyes do in dim light, and there’s nothing wrong with that on its own. But that makes it harder to focus our eyes (ask any photographer about depth of field).
As a result, the ciliary muscle in our eyes has to work harder to smoosh the eye’s lens into shape. In other words, you’re more likely to get eyestrain.
To prevent digital eyestrain, the headaches and sore eyes that can result from reading on screens of any color, the AOA suggests looking at something 20 feet away, for 20 seconds, every 20 minutes. In other words, take a break from your phone sometimes.
You aren’t going to permanently damage your eyes by using dark mode all the time, but it’s probably best to use it sparingly.
Dark mode for text messages or occasional use of your phone is fine, as is dark mode when you’re watching videos or playing games that don’t require you to read or observe fine-grained details.
But if you’re going to spend time scrolling down a wall of text, your eyes may be better off with dark text on a light background.