What Does Dark Mode Do?

Dark mode changes the way your device’s OLED screen emits light. The night-friendly setting reduces the overall brightness output from the screen, making less of a contrast with the world around you. Many people choose to use dark mode in the evening, when they're outside at night, or when they're sitting indoors in a dimly lit room.

When in a dark setting, looking at a screen with a dark background may feel more comfortable than looking at a bright screen because you'll see less glare in dark mode. Dark mode should make it easier for your eyes to adjust from your dimly lit surroundings to your phone screen, which may reduce eye strain and minimize eye fatigue.

This is why car navigation systems and GPS devices switch to dark mode after sunset. It's safer for drivers to periodically glance at a darkened screen while they're traveling along dark roads, rather than a fully lit device. A fully lit device requires the eyes to adjust to the brightness, then readjust to darkness when they look back at the road.

The Benefits of Dark Mode

Very little research has examined the benefits of choosing dark mode over light mode, possibly because it's a relatively new feature for phones. Much of the research has focused on dark mode's ability to help people fall asleep more easily at bedtime because it reduces blue light. Exposure to blue light from phones mimics sunlight, and it can delay the production of the sleep-inducing hormone melatonin as bedtime approaches. Your circadian rhythms can eventually become disrupted because blue light suppresses melatonin. Dark mode can reduce blue light exposure and has been shown to help encourage nighttime melatonin production.

Spending too much time looking at bright screens throughout the day may lead to digital eye strain, with symptoms like eye fatigue or blurry vision. Screen brightness is only one factor — people tend to blink less frequently when looking at screens, which may lead to dry eyes or strained eyes. Blinking more frequently helps reduce symptoms, but no research has shown that looking at devices in dark mode encourages more frequent blinking. Many people also think switching from light mode to dark mode can save the battery life of phones and tablets. However, a study by Purdue University found that battery savings are only around 3-9%.

Why Should You Use Dark Mode?

People who spend all day looking at computer and phone screens may benefit from using dark mode, especially in the evening. You may be at greater risk of digital eye strain or fatigue if you use devices for several hours every day. Looking at words and images on a darker background may give your eyes a rest from exposure to bright light, which may help prevent or relieve discomfort. Using dark mode alone may not eliminate device-related eye strain or fatigue. Combine the practice with eye-friendly habits like looking up from your phone every 20 minutes and making an effort to blink more often.

Why Shouldn’t You Use Dark Mode?

For people with certain eye conditions, looking at white text on a dark screen may cause a halo effect, which is when a blur of light surrounds the brightness amid the darkness. This may affect people with myopia (nearsightedness), astigmatism (an irregularity in the curvature at the front of the eye), or presbyopia (an age-related decline in the ability to focus on things that are near the eyes). The halo effect isn't exclusive to smartphones and other digital devices; any bright light that's viewed within a dark field of vision may cause this effect. For example, some people who have myopia, astigmatism, or presbyopia see halos around headlights or streetlights when they drive at night.

If you experience the halo effect when you put your smartphone on dark mode, you may see things more clearly if you switch to regular mode (black letters on a white screen), then turn the brightness down considerably during evening hours. Some devices may also have a feature that automatically adjusts screen brightness or shifts from blue to yellow light after a certain time. Take a look at your device’s brightness settings to see if you can configure a custom light filter.