The Pros and Cons of Dark Mode for the Eyes and Health

The argument for whether a dark theme is more damaging or protective for the eyes is not supported by substantial proof. Nonetheless, eye doctors and ergonomics experts generally concur that it is sensible to utilize a light theme in well-lit daytime conditions and switch to a dark mode in low-light conditions at night.

Dark Screen Mode

The use of a dark screen mode, also known as night mode, is a feature available on many digital devices that adjusts the screen brightness by presenting white or colored text on a black background, instead of the conventional light mode with dark text on a white or gray background.

In the technical world, display configurations where the text is dark against a light background are referred to as having a positive polarity, while those where the text is light against a dark background are called negative polarity.

The Evolution of Dark Mode: From CRT Monitors to OLED Displays

Prior to the 1980s, dark mode was widely used on home computers as a result of the design of early CRT monitors. These monitors utilized cathode ray tubes that produced a concentrated beam of electrons to form images on the screen coated with a luminous material known as phosphor. The use of green phosphor was cost-effective, leading to the popularity of computers that featured a black screen with green text.

However, not everyone appreciated the dark screen, which was favored by programmers and engineers. Most users were accustomed to black text on white paper. As a result, monitors with positive polarity soon emerged, featuring a light screen and dark text.

By the early 1990s, positive polarity monitors had become the standard, first for CRT monitors and then for the more compact LCD monitors that replaced them.

LCD displays are similar to a sandwich of two polarized glass panels, with liquid crystals sandwiched in between. A light source is positioned on one side of the screen and illuminates the liquid crystals, which act as the pixels that make up the image. Under the influence of an electric current, the crystals can either allow light to pass through or block it. The light passes through colored filters and ultimately forms an image on the screen.

This means that on an LCD device like a smartphone or laptop, the light source will consume the same amount of energy regardless of whether the screen is in light or dark mode.

Starting from the mid-2000s, LCD displays were gradually being replaced by OLED displays, which produce an image using organic pixels-LEDs. Unlike LCD displays that need backlighting to function, the image in OLED displays is created by pixels that emit light on their own.

When all the pixels are turned on, the background appears white, and when turned off, the screen doesn’t emit light, hence appearing black. The benefit of this is that turned-off pixels do not consume energy, which can help save a small amount of energy on battery-powered devices – roughly 3% to 9% – when in negative polarity mode.

However, the amount of energy saved can significantly depend on the brightness level of the smartphone screen. For instance, reducing the brightness level from 100% to 50% can reduce the energy consumption of an OLED device by 10 times, regardless of the mode.

The dark mode, although not energy-saving for the LCD displays of most modern laptops, has become widespread due to its availability in various popular services and applications. Modern operating systems like Windows, MacOS, Android, and iOS also support the dark mode.

Additionally, all major OSs automatically switch to the dark mode when it’s dark, which has made many users accustomed to using it. Another benefit of using the dark mode is the potential health benefits it can bring.

What do we know about the benefits of dark mode for health

No strong proof exists to either support or dispute the impact of dark mode on health due to the limited number of studies conducted on the topic. However, the limited research available does offer some insight into how dark mode may affect one’s well-being.

The Benefits of Dark Mode on Sleep Quality and How to Enable it on Mobile Devices

It all revolves around melatonin, a hormone produced in the brain that regulates our internal clocks. When light fails to reach the eye’s retina for an extended period, it sends a message to the brain area where melatonin is produced. The moment this hormone appears in the bloodstream, the body recognizes that night has arrived and falls asleep. However, when light reaches the retina, melatonin production stops, signaling the body to wake up and start the day.

Blue light is believed to be the most invigorating of all light streams, but screens of our devices emit this type of light, which can interfere with melatonin production. Studies have shown that individuals who use smartphones or e-books for one to two hours before bedtime have more difficulty falling asleep and the quality of their sleep is not as deep or restful as those who do not use devices.

Fortunately, activating dark mode on your device will reduce the amount of light emitted, including blue light. This means that individuals who switch their devices to dark mode before bed are likely to have a better sleep than those who do not.

Here’s how to activate Dark Mode on modern mobile operating systems:

• For iOS: Go to “Settings”, select “Screen and Brightness”, and choose “Appearance”. You can schedule when Dark Mode turns on: at a specific time or from sunset to sunrise.
• For Android: Navigate to “Settings”, select “Screen”, and select “Dark Theme”. You can set a schedule: at a specific time, from sunset to sunrise, or when the special night mode with warm light is on.

While there have yet to be experiments comparing the experiences of people who sleep with Dark Mode and Light Mode, it is not possible to definitively say that Dark Mode has a better impact on sleep. Furthermore, reducing blue light’s impact can be achieved without Dark Mode, simply by reducing the brightness.

Reducing Digital Eye Strain: Tips and Recommendations

A high proportion of individuals who regularly use electronic devices experience discomfort, commonly referred to as digital eye strain. Symptoms such as dry eyes, blurred vision, and headache can arise due to decreased blinking when using screens for prolonged periods of time. A 2018 study published in the British Medical Journal found that the prevalence of digital eye strain symptoms among computer users can be as high as 50% or more.

To combat digital eye strain, American ophthalmologists recommend several measures, including using artificial tears, taking breaks from screens every 20 minutes and looking at distant objects for 20 seconds, keeping devices away from the face, using a matte anti-glare screen filter, and wearing glasses while using a computer instead of contact lenses.

There are several factors that contribute to digital eye strain, one of which is the mismatch between the brightness of the screen and the ambient lighting. Using a dark theme in a low-light environment can alleviate eye strain, as it offers better contrast and less flicker compared to a light theme. However, it’s not recommended to use dark mode in well-lit rooms or during the day, as the screen will be darker than the surrounding environment and cause eye strain. In these situations, screens with positive polarization are less likely to cause eye strain due to reduced flicker.

Moreover, American psychologists found in a 1997 survey that reading dark text on a light background is more comfortable than reading light text on a dark background. The two preferred color combinations were black text on white and black text on gray. A 2013 study on display polarization and its impact on visual acuity and reading comprehension showed that both young and healthy elderly people have better text discrimination and error detection on screens with positive polarization. This is because constricted pupils on a bright background improve text scanning, while dilated pupils on a dark background result in less clear focus on text.

It’s important to be mindful of these factors when using gadgets to reduce digital eye strain and its symptoms such as dry eyes, blurred vision, and headaches. American ophthalmologists recommend using artificial tears, taking breaks from screens every 20 minutes, holding devices at arm’s length, using anti-glare filters, and working with glasses instead of contact lenses. By following these recommendations and being aware of screen brightness and color, you can help reduce the discomfort associated with prolonged gadget use.

Light Sensitivity and Its Effects on Vision

Photophobia, or light sensitivity, refers to discomfort experienced in the eyes as a result of exposure to bright light. This discomfort is typically a symptom of other underlying conditions such as uveitis (inflammation of the blood vessels in the eye), meningitis, or migraines.

To relieve the discomfort associated with photophobia, individuals are encouraged to wear sunglasses when outdoors and to keep rooms dark. For those who work from home, using dark mode on electronic devices can also be helpful.

However, it’s important to note that dark mode may not be effective for all vision problems. For example, some individuals with astigmatism have reported that white text appears blurred and difficult to read on a dark screen. Thus, for those with both photophobia and astigmatism, using dark mode on electronic devices may not be suitable.

Conclusion

The Canadian Center for Occupational Health and Safety has determined that the most important consideration in selecting a light or dark theme is the individual’s preference. If someone finds it more comfortable to work with a dark theme, even during the day, they are free to do so. However, for many people, it is likely more comfortable to use a light theme during the day and a dark theme in the evening.