Prevent Eye Strain! Read Ebooks with Eye-Friendly Settings
Reading involves looking at text for long periods of time, which naturally leads to eye strain. However, by adjusting to eye-friendly settings, you can reduce or even prevent eye fatigue.
Modified at: 2025.9.12Posted at: 2022.9.6
How Should We Consider the Physical Impact of Reading Ebooks?
When using electronic devices, considerations for the body can be guided by the "Guidelines for Occupational Health Management in VDT (Visual Display Terminals) Work," established by Japan’s Ministry of Health, Labour and Welfare.
According to the guidelines:
- Minimize the difference in brightness between the display and the surrounding environment
- Reduce reflections on the display
These are the main recommendations related to displays.
Although ebook readers are not specifically mentioned in the guidelines, reading ebooks is quite similar to VDT work as defined there, and the guidelines should be used for reference.
What Settings Should Be Used When Reading Ebooks?
Screen Brightness
When reading ebooks, we are not reading printed text on physical paper but text and images shown on a display. Without backlighting, the display would appear completely dark, so most ebook readers—except for some models—come equipped with backlights.
The brightness of the backlight is often adjusted according to "what feels comfortable to the individual," but the key factor is the difference between the display and surrounding brightness. Large contrasts are said to cause eye strain. This is essentially the same reason why looking at a bright screen in a dark room feels tiring.
Smartphones and Tablets
Modern smartphones and tablets with ambient light sensors can automatically adjust the backlight in response to surrounding brightness, but it is also advisable to manually fine-tune it for optimal comfort.
Blue light emitted by backlights is considered "harmful to the eyes, similar to ultraviolet rays." However, there is debate as to whether reducing blue light effectively lowers eye strain.
In addition, prolonged exposure to bright light can stimulate the brain and cause wakefulness, which is why it is especially recommended to lower screen brightness at bedtime.
Ebook Readers
Ebook readers generally use front lighting that illuminates the electronic paper from the sides, which has a far smaller impact on the eyes compared to LCD screens that shine directly toward them.
Because electronic paper is visible even without backlighting, simply letting ambient light hit the screen makes it fairly easy to read. Therefore, you can comfortably keep the front light relatively dim.
Many people mistakenly block light when holding ebook readers, just like with smartphones, but if you adjust the angle to allow natural light—such as sunlight—to fall on the screen, you can read comfortably even with very low backlight.
Overall, ebook readers with electronic paper are less harmful to the eyes compared to smartphones.
Font Size and Line Spacing
Naturally, larger text is easier on the eyes. If text is too small, you are forced to squint, leading to eye strain.
However, excessively large text may feel stressful for reading flow. A useful rule of thumb is to select "one size larger than the text size you consider easy to read."
Line spacing is equally important. If line spacing is too narrow, your eyes must move within a tighter range, which can be tiring for some people.
Preferences vary, but since ebooks are digital, you can freely adjust line spacing to find the layout that minimizes stress and fatigue for your eyes.
Surrounding Brightness
The brightness of your reading environment is more important than many realize. This is especially true for ebook readers with electronic paper, which can be read clearly even with lower backlight levels in brighter rooms. Whenever possible, read in a well-lit area.
The difference in brightness between the display and the surrounding light is also critical. For example, imagine using a smartphone with backlight in a pitch-dark room: the contrast causes strain. Similarly, using maximum backlight brightness in a bright environment can also cause strain.
Reading on a dim screen is not ideal either, so aim to find a balance between your display brightness and the ambient light for the most comfortable ebook reading experience.