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Dark Mode vs. Light Mode

In recent years, dark mode on displays has become the in-thing. With major OS vendors offering a system-wide dark mode option, and an ever-increasing number of applications and sites choosing to bring dark mode front-and-centre, there is little doubt on its popularity with consumers.

Advocates for dark mode often tout several claims in its favour:

  • It is easier on their eyes, reducing strain and fatigue
  • It saves uses less energy, and thus prolongs battery life on mobile devices

Personally, however, I have always been more partial towards light mode: using it where offered, except at night where I set my smartphone to automatically activate night mode. And though it may not have been the “better choice”, I chalked it up to my personal preference.

Yet recently, I came across this article by Kev Quirk, sharing some information he discovered regarding the oft-touted benefits of dark mode. And I realise that perhaps I am not the only one who believes light mode to be generally superior. Thus, I was inspired to try and find out a little more.

Is this information new? #

It turns out, studies have been conducted on the relative legibility of text on interfaces with positive polarity (black text on white backgrounds) versus negative polarity (white-on-black).

A few minutes of searching online surfaced several articles by different sites discussing the issue of dark-vs-light. Of note, an article by Adam Engst for TidBITS cites two journal articles, one from 2013 in Ergonomics, and another from 2017 in Applied Ergonomics. As the article’s author, Adam Engst, summarised (emphasis mine):

… a dark-on-light (positive polarity) display like a Mac in Light Mode provides better performance in focusing of the eye, identifying letters, transcribing letters, text comprehension, reading speed, and proofreading performance, and at least some older studies suggest that using a positive polarity display results in less visual fatigue and increased visual comfort. The benefits apply to both the young and the old …

In addition, another article by Adamya Sharma for Android Authority raises a different point: for people with astigmatism1, light mode interfaces are easier to read. This is due to the increased light levels lessening the “deformative effects” from astigmatism.

As such, it appears that the popularity of dark mode may not truly be due to the touted benefits. As Lilly Smith writes for Fast Company:

… in regard to usability and legibility, dark mode isn’t actually better. Rather, it may be more indicative of a “bigger minimalism trend,” as Budiu puts it, or simply the increasing personalization of user interfaces overall.

Is light mode the winner, then? #

More recently, Nielsen Norman Group has also released an informal literature review that cites the aforementioned two journal articles, and brings in some additional research.

One point raised was the potential for long-term effects of sustained reading via light mode interfaces. According to a study published in Nature Research’s Scientific Reports in 2018, prolonged exposure to light-mode may be associated with myopia (sample size: 7). Of course, further studies need to be done before a conclusion can be reached, but the research indicates there is such a possibility.

Furthermore, Nielsen Norman Group’s article highlights the results of another study from 1985, by Gordon Legge and colleagues at the University of Minnesota: individuals with cloudy occular media2 — most commonly caused by cataract — fared better when reading with dark mode interfaces.

Does dark mode save power? #

The answer to this depends on the display in question.

Most displays in the market are liquid crystal displays (LCDs). Such displays require the use of a backlight to produce a visible image, as they do not produce light themselves. Many displays marketed as LED screens are, in fact, LED-backlit LCDs. Consequently, whether the content is dominated by white or black, the backlight stays on and continues consuming energy. In fact, a post by Bill Weihl on Google’s official blog suggests that displaying black on flat-panel monitors may actually consume more energy.

Nowadays, however, higher-end phones and displays utilise a newer techology known as Organic LED (OLED). In such screens, each pixel is responsible for both colour and brightness: there is no longer need for any backlight. With such devices, the use of dark mode does lead to considerable reduction of energy consumed, according to this article by Kevin Purdy for iFixit.

What does this mean? #

For individuals with certain medical (eye) conditions, the debate between light and dark mode may not be clear cut.

But for the average person with normal vision, light mode appears to beat dark mode, with regards to performance: it leads to less visual fatigue and better overall reading performance compared to dark mode.

As for energy consumption, it depends on the display in use: many higher-end phones come with OLED/AMOLED displays, and dark mode is useful for such devices. But on lower-end phones, and most desktop/laptop monitors, there is no difference in energy consumption since LCD/LED displays are used.

At the end of the day, the dark-mode hype appears to mostly be a matter of personal preference, and that is a perfectly valid reason. Personally, I believe I will stick to using light mode, as I am more comfortable with it.

  1. An eye condition resulting in blurred vision, due to abnormalities in the lens of the eye. See Wikipedia for more information. ↩︎

  2. The transparent substances of the eye, including the cornea and lens. See The Free Dictionary for a fuller definition. ↩︎