When you work on a computer for a long time, your eyes get shaky, your shoulders get stiff, and you have trouble sleeping at night... Have you ever had such an experience? In fact, it may have something to do with theblue light emitted from the screen or the display settings.

In this article, based on information as of March 2026, we have compiled 5 blue light countermeasures that you can take right now without spending money, focusing on how to use the Night Mode that comes standard with Windows 11. We will answer the question "Are blue light blocking glasses really effective?" based on the latest research results.

What exactly is blue light? Effects on eyes and sleep

Blue light is blue light with a wavelength of 380 to 500 nm (nanometers). It is included in sunlight, but a lot of it is also emitted from computer and smartphone screens.

Roughly speaking, the current scientific consensus is that blue light during the day is fine but too much exposure at night can be bad for sleep.

According to a Harvard Medical School study (2019), blue light at night can suppress the secretion of the sleep hormone melatonin by up to 85%. In other words, if you look at a bright computer screen right before bed, your brain will think it's still daytime, making it harder to fall asleep.

On the other hand, regarding the story that "blue light damages the eyes themselves," the Japan Ophthalmological Association published an opinion paper in April 2021 states, "It is unlikely that blue light that we are exposed to in daily life will cause damage to the retina." Screen brightness, reduced blinking, and posture are more important causes of eye fatigue than blue light itself.

Measure 1: Turn on "night mode" in Windows 11 (top priority)

Windows 11 comes standard with Night Mode, which reduces blue light. No additional software is required and you can turn it on in 30 seconds from setup.

Night mode setting procedure

  1. Open Settings (Start menu → gear icon or Windows key + I)
  2. Click System → Display
  3. Turn on the "Night mode" switch under "Brightness and color"
  4. Click “>” on the right side to adjust the strength slider

Moving the slider to the right will make the screen a warmer color (orange-ish) and increase the amount of blue light cut. Recommended range is 30-50%. If the colors change too much, it will interfere with photo editing and design work, so adjust as much as you can comfortably.

Automatic switching by schedule setting

If you turn on "Night mode schedule", night mode will be enabled automatically at the specified time. The recommended settings are as follows.

  • Select Sunset to Sunrise (only available if location services are turned on)
  • Or manually set around On: 19:00 / Off: 7:00

By the way, you can also turn night mode on and off with one click from Quick Settings, which is displayed by clicking the network speaker icon at the far right of the taskbar (or pressing Windows key + A).

Measure 2: Switch to dark mode to reduce screen glare

What you want to use in conjunction with night mode is "Dark Mode". Since the entire screen is based on black, glare is significantly reduced even when working in a dark room.

Dark mode setting procedure

  1. Open Settings → Personalization → Colors
  2. Select "Dark" in "Select Mode"

With just this, standard Windows applications such as the settings screen, Explorer, and Notepad will have a black background.

If you select "Custom", you can specify light/dark for Windows system parts (taskbar, etc.) and applications separately. For example, a combination of ``black taskbar and white apps'' is also OK.

Please note that browsers such as Chrome and Edge may require dark mode settings. In Chrome, you can switch to "Settings" → "Design" → "Dark".

Measure 3: Adjust screen brightness to "same as paper"

What is surprisingly often overlooked is Adjusting the brightness (brightness) of the display. According to display manufacturer EIZO's explanation, the cause of eye fatigue is that the screen is too bright.

There is an easy way to check. Place a piece ofwhite copy paper next to the screen and compare the white of the screen with the white of the paper. If thescreen is noticeably brighter, reduce the brightness.

How to adjust the brightness

  • Open Quick Settings on the right end of the taskbar (Windows key + A) and adjust with the sun mark slider
  • For an external monitor, lower the brightness from the menu button on the monitor itself
  • As a guide, a brightness of around 120cd/m² is considered to be an appropriate value for a general office environment

Measure 4: Rest your eyes frequently with the "20-20-20 rule"

Even if your display settings are perfect, your eyes will get tired if you stare at the screen for long periods of time. What we recommend is the 20-20-20 rule, which is also recommended by ophthalmologists.

The rules are simple.

  • Every 20 minutes
  • 20 feet (approximately 6 meters) ahead
  • Stare for 20 seconds

In short, all you have to do is "look blankly into the distance once every 20 minutes." This alone will relax the eye's focusing muscles (ciliary muscles) and significantly reduce eye strain.

The Ministry of Health, Labor and Welfare also recommends taking a 10-15 minute break every hour in ``Guidelines for occupational health management in information equipment work'' (revised in 2019). It's even more effective when combined with the 20-20-20 rule.

If you tend to forget, set a 20-minute timer in the Clock & Alarms' app in Windows, or use the EyeCare 20 20 You can also use free apps like ``20''.

Measure 5: Prepare the environment around the monitor

Eye fatigue is actually caused by factors other than screen settings. Please check the following points.

Screen position and distance

  • Ideal distance between screen and eyes is 50-70cm
  • Set the screen so that the top edge of the screen is at eye level or slightly below
  • Avoid looking up as your eyes will open wide and dry easily

Room lighting

  • Don't look at bright screens in a dark room. Make the entire room moderately bright
  • Check whether light from windows or lighting is reflected on the screen
  • Using a monitor light (screen bar) is recommended as it can illuminate your area without reflecting on the screen

Be conscious of blinking

It is said that while working on a computer, the number of blinks is reduced to about 1/3 of the normal number (normally about 20 times a minute → about 7 times when staring at a screen). Make a conscious effort to blink more or keep eye drops for dry eyes on hand.

Are blue light blocking glasses effective? Conclusion of the latest research

You may think, "Maybe I should just buy blue light blocking glasses," but the latest research shows that the effect is limited.

An international meta-analysis published in the medical journal Cochrane Database of Systematic Reviews in August 2023 concluded that ``there is insufficient evidence that lenses with blue light filters significantly reduce eye strain.''

In addition, Japan Ophthalmological Association/Japan Ophthalmological Association issued an opinion statement in 2021 stating that ``There is no basis for recommending blue light-blocking glasses for children.''

However, it has been suggested that wearing glasses at night to block blue light may alleviate the suppression of melatonin secretion and improve sleep quality. In other words, although there is insufficient evidence to prevent eye strain during the day, it does make some sense as a measure to prevent nighttime sleep.

In short, it is cheaper and more effective to review your Windows 11 settings and work environment as introduced in this article than to buy blue light blocking glasses.

FAQ

When I turn on night mode, the screen turns orange and it's disgusting. What should I do?

Move the "Strength" slider in "Settings" → "System" → "Display" → "Night mode" to the left to weaken it. If it is around 20-30%, there will be little change in color and it can be used without any discomfort. You can also turn it off only when editing photos or videos.

What is the difference between dark mode and night mode?

Dark mode is a function that changes the "background color" of the screen to black, and its purpose is to reduce glare. Night mode is a function that changes the "color temperature" of the entire screen to a warmer color, and its purpose is to cut blue light. Turning both on at the same time creates a more eye-friendly environment.

Is there anything worse for your eyes than blue light?

Yes. Staring at a screen at a close distance for long periods of time, causing dry eyes due to decreased blinking, and looking at a bright screen in a dark room are more taxing on the eyes. The most effective measures are practicing the 20-20-20 rule and adjusting the screen brightness.

Which is better for night mode, scheduled or manual?

Basically, setting a schedule is recommended. If you select "From sunset to sunrise", it will switch automatically, so you won't forget to set it. If you have turned off location services, manually set it to something like "7:00-7:00."

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