Using a smartphone in a dark room may seem harmless, especially at bedtime. But the strong contrast between a bright screen and a poorly lit environment can make the eyes work harder and contribute to visual discomfort, dryness and headaches.
A bright screen in a dark room
It is a familiar habit. The lights are off, but the phone remains in hand. One message leads to another, then a few videos or social media posts, and suddenly several minutes have passed.
Although using a phone in the dark does not automatically damage the eyes, it can increase visual discomfort. In a dark environment, the pupils naturally dilate to allow more light into the eyes. At the same time, the phone produces a concentrated source of light directly in front of the face. The eyes therefore have to constantly adapt to the difference between the dark surroundings and the bright screen.
The problem can become more noticeable when the screen is used for a long period without a break.
The eyes also have to keep focusing
Distance matters too. Smartphones are generally held relatively close to the face. Reading small text or watching videos at this distance requires continuous focusing.
When this continues for a long time, some people may experience what is commonly known as digital eye strain. Symptoms can include tired or heavy eyes, temporary blurred vision, headaches, difficulty focusing and a feeling of discomfort around the eyes.
Another factor is blinking. People tend to blink less frequently when concentrating on a screen. Reduced blinking can cause the surface of the eyes to become drier, potentially leading to burning, irritation or a gritty sensation.
A few simple changes can help
The easiest solution is not necessarily to stop using a phone completely. Instead, the viewing conditions can be improved.
Avoid using the phone in a completely dark room. A soft ambient light can reduce the contrast between the screen and its surroundings. The screen brightness should also be adjusted to a comfortable level rather than kept at maximum brightness.
Holding the phone at a reasonable distance and increasing the text size can also reduce the effort required to read. Dark mode may make viewing more comfortable for some people, although its effect on eye strain varies from one person to another.
Regular breaks are equally important. The 20-20-20 rule is one simple approach: every 20 minutes, look at something about 20 feet (6 meters) away for at least 20 seconds. Remembering to blink regularly can also help limit dryness.
When should you seek advice?
Occasional tired eyes after prolonged screen use are generally not a reason for alarm. However, persistent or recurrent eye pain, significant blurred vision, severe headaches, redness or other unusual symptoms should not simply be attributed to the phone.
If such problems continue despite taking breaks and reducing screen strain, an eye-care professional can determine whether another condition is involved.
The goal is therefore not to fear the phone screen, but to use it in conditions that give the eyes regular opportunities to rest.
