Dark mode – which swaps the standard white background for black – has become the de facto display option for the most health-conscious internauts. Like pulling down the shades or donning sunglasses, dark mode invites a slightly subversive, Mr Robot-esque feel. Indeed, blackout displays have always been the mode of choice among developers assembling code late into the night.
But dark mode is democratising. It’s now available on Android phones and Apple’s Mojave operating system, as well as a host of apps including Microsoft Outlook, Safari, Reddit, YouTube, Gmail and Reddit (a full list of websites offering dark mode can be found here). Responding to complaints that its dark navy dark mode wasn’t dark enough, Twitter rolled out a true dark mode dubbed ‘Lights out’ earlier in 2019.
A big driver of dark mode is aesthetics. One Twitter user’s assessment: “Night mode Twitter just 1000% more dope than regular one”, is pretty representative of the internet’s reaction to dark mode. Spotify, which selected a dark background as its standard mode, chose this look after testing different designs on its users, who were overwhelmingly in favour of this shady aesthetic. “We believe that when you have music or art that’s very colourful and very artistic, and you have beautiful cover art for music, that it really shows more clearly visible in a product like this, when it’s about entertainment,” Michelle Kadir, director of product development at Spotify, told Fast Company.
But beyond style, the widespread roll-out of dark mode has triggered a slew of dubious claims about its proposed benefits, covering assertions that it helps concentration, eye strain and battery life. The question is, does the average computer user stand to gain anything from slipping into this shadowy mode? Here, we unpack some of the most prominent claims about dark mode, and whether they stack up.
Dark mode helps eye strain
In just a few decades, screens have populated the earth at an alarming rate – now ubiquitous in the home, office and our sweaty palms. From the exhaustive list of concerns sprung from the internet’s flickering omnipresence, those relating to eye health rank fairly low. But this doesn’t mean that people aren’t adversely affected. A 2018 study on digital eye strain (DES; also known as computer vision syndrome) published in the British Medical Journal notes that its prevalence might be as high as 50 per cent or more among computer users.
This condition can be caused by blinking less than usual when looking at a screen. Our standard 15 blinks a minute can dip as low as 3.6 when we’re gazing at our phones or computers – contributing to dry eyes. According to the American Optometric Association, symptoms associated with DES can include headaches and blurred vision.
No wonder then, that anything offering a solution to this condition is touted as a miracle cure. One of the oft-repeated claims about dark mode is that it’s exactly that, but is this based on fact? Anna Cox, a professor of human-computer interaction at UCL, dispute this is the case, saying, “I’m not aware of any robust evidence that white text on black background reduces eye strain”.
However, the effort of looking at a screen can vary a lot depending on your surroundings. In a dimly lit environment, where the main light source is your screen, the greater the eye strain provoked by a brightly lit display. “In a darkened room, the darker colours of dark mode could be perceived as less jarring and lull people into spending longer using the app,” says Aneesha Singh, professor of human-computer interaction at UCL. Conversely, in a brightly lit environment, a darker screen can actually force your eyes to work harder.
If truly concerned about eye strain or dryness, you might be better off investing in artificial tears or a matte screen for your device. For the device itself, recommendations include raising the contrast of your screen, or adjusting the brightness so it’s no lighter or darker than your surroundings. You might want to check light sources around you too – glare from overhead lighting reflected on your screen can make it harsher. Adjust your screen at or below eye level – having your screen above eye level can dry your eyes out further.
But the best solution might be to drag yourself away from your computer altogether. Limiting screen time is the top tip from the Mayo Clinic. You can also make use of the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds.
Dark mode makes text more legible
In terms of readability, ensuring a higher contrast between text and background is more important than colour scheme, according to Cox. If the contrast is the same between normal and dark modes, she says we might not expect a difference in legibility, although our familiarity with black text on a white background might offer this display mode a slight edge.
Research published in 2013 by psychologists Cosima Piepenbrock and Susanne Mayr showed that accuracy and performance are better in positive polarity conditions (i.e. black text on a white background). The study involved participants carrying out both visual acuity tests and proof reading tasks. On these tasks, participants both read faster and/or spotted more mistakes in the positive polarity condition.
The researchers put this down to the fact that when we look at a bright background, our pupils constrict and increase acuity while scanning text. When looking at a black background, the opposite effect occurs, and dilated pupils make it harder to focus on the text. Mayr’s research initially proposed that these effects might be reversed for elderly populations, but found this wasn’t the case. However, this might be one of the keys as to why people spend longer on these apps when this mode is enabled – because it reduces legibility and makes reading more effortful.
This effect is even truer for those with astigmatism according to Singh, a condition where the eye is not spherical that affects close to 50 per cent of the population. However, eye conditions causing a sensitivity to light such as photophobia or keratoconus or those suffering loss of vision might benefit from the inky display mode.
Dark mode is better for battery life
One claim about dark mode that has a greater grounding in evidence is its battery saving attributes. However, this depends on the type of screen your phone has. For OLED (organic light-emitting diode) screens, dark mode does offer a battery conserving benefit. This is because in this screen type, each pixel lights up individually, meaning that when the pixel is black it's deactivated. For older LCD screens there is no advantage because these are backlit, meaning that even when displaying black, the pixels are lit up.
Until recently, most phones were made with LCD screens. The iPhone X was the first Apple phone to launch with an OLED screen. Other phones with OLED displays include the Samsung Galaxy S10 and the Huawei Mate P30. For these phones, dark mode can offer healthy battery saving capabilities. A report from iFixIt found there was a 63 per cent drop in power usage for an Android phone displaying a screenshot of Google Maps in night mode.
Dark mode increases concentration and decreases distraction
Dark mode has been associated with claims about our ability to focus: Apple launched Mojave’s dark mode with the promise of a “distraction-free working environment that’s easy on the eyes — in every way.” But is there any reason to believe that dark mode delivers a boon for concentration?
“If anything, lighter backgrounds have been proven to be better for concentration and performance,” says Singh. Cox too, disputes the claim that dark mode would assist concentration, saying she is not aware of “any mechanism” that would mean this is the case. This is explained by the nature of distraction, which come from two sources: one is external – your phone buzzing or someone shouting your name – and the other is internal: your brain spontaneously popping on an embarrassing memory clip from five years ago. “Unfortunately, externally driven distractions don’t just disappear by changing their colour, and internally driven distractions aren’t inhibited by looking at something dark,” says Cox.
However, there might be more reasons to believe that dark mode could assist focus. Screen flicker – which is caused by the computer screen’s refresh rate – has been shown to affect concentration. Nilli Lavie, professor of psychology at UCL specialising in neural mechanisms of attention, distraction and visual awareness has examined flicker in a research setting. “We have shown that the brain can respond to flicker in surround, even if you're not consciously aware of it,” she says. Lavie suggests that a pure black backdrop would eliminate the presence of flicker, and thus eliminate this source of subconscious static.
“In our research, we always use dark mode,” says Lavie, whose work examines distractibility. Her experiments present stimuli in white against a black background, rather than vice versa, in experiments where the participant must look at the screen for an hour or longer. “Because we have found that it’s disturbing. We found that a white background produces some interference in its own right and can reduce the interference from the other stimuli.”
Twitter has found that users spend longer on the app when this mode is enabled. But rather than greater concentration, this could be because this mode is less harsh for users scrolling in bed. Contrary to what apps are claiming about dark mode – that it’s designed to help us concentrate and soothe us – the true motive could be that which underlies most app design decisions: simply to keep us on them for longer.
Dark mode is better for bedtime
By now you’re probably familiar with public (screen) enemy number one: blue light. This strain of the colour spectrum jolts our brains into a state of wakefulness by tampering with its sleep promoting apparatus and makes it harder to get a restorative night’s sleep. A widely circulated 2018 study demonised blue light even further by suggesting it contributed to macular degeneration, but since then this research has been denounced by the American Academy of Ophthalmology for relying on flimsy methods and not taking cells from eyes.
“Light from iPads and LED screens can produce blue-white light in quantities that affect melatonin and relatedly sleep and circadian rhythms," says Singh. "This could be improved by true dark mode – if it works by not using LEDs in the background. This needs more research though as it's just become the hot new thing.”
True dark modes reduces the levels of blue light emitting from our screens, but this can also be achieved to some extent by switching into night modes, that replace the harsher blue light with more melatonin-friendly orange hues, or by adjusting your colour temperature. However, limiting screen time entirely in the hour or two before bed is the best course of action.
This article is part of our in-depth series investigating how technology is changing wellbeing, happiness and the spaces we inhabit.
From what drives the world's happiest countries to the apps we use on a daily basis, we're looking at how technologies and ideas are changing our wellbeing – for better or worse.
Click here to read more articles from this series.
– Scandinavia's reign as the happiest place on Earth is ending
– High-flying CEOs are trying to brain-zap their way to happiness
– The design secrets Nasa's using to keep astronauts happy in space
This article was originally published by WIRED UK
