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
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,
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
: every 20 minutes, look at something 20 feet away for 20 seconds.
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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.
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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.
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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?