How to Reduce Eye Strain from a Computer: Ranked by Impact
Most guides on this topic give you ten equal-weight tips. This one does not. The six interventions below are ordered by their likely impact on the most common causes of computer eye strain. Work through them in order. The first two address problems that affect nearly everyone who works at a screen for more than a few hours. The last one applies to a specific subset of monitor hardware. Start at the top.
1. Lower screen brightness to match your room
A display significantly brighter than the room it sits in forces your pupils into continuous adjustment as your gaze shifts between the screen and the surrounding space. Over a full workday, this is genuinely tiring. Most people run their screens at or near maximum brightness by default, which was appropriate for a bright retail showroom and is not appropriate for a home office or a dim conference room.
How to check: Look from your screen to a white sheet of paper sitting in normal room light. If the paper looks noticeably darker than the screen, reduce brightness until they roughly match. You may need to do this again in the evening when ambient light drops further.
If reducing hardware brightness makes symptoms worse rather than better, skip ahead to number 6. That is a specific hardware issue.
2. Shift color temperature in the afternoon and evening
Default display color temperature is around 6500K, calibrated for daylight. Running it at that level late in the afternoon and into the evening adds short-wavelength light load to the visual system at the time it is least equipped for it. A warmer setting (closer to 3000K to 4000K in the afternoon, 2000K to 2700K in the evening) reduces that load without meaningfully affecting screen legibility.
How to do it on macOS: System Settings → Displays → Night Shift. Set it to go warm in the early afternoon rather than just at sunset.
How to do it on Windows: Settings → System → Display → Night Light. Enable the schedule.
For more control: Circadian Shield handles both brightness and color temperature on a continuous curve tied to your location's solar position. It also uses software-layer brightness control that bypasses hardware PWM dimming, which matters for tip 6. Basic plan is $4/month or $39/year. Try it free on Mac or Windows.
3. Set a break timer for accommodation fatigue
Display adjustments address the luminance and color causes of eye strain. They do not address accommodation fatigue, which is the ciliary muscle exhaustion from holding near focus for hours. The 20-20-20 rule targets this directly: every 20 minutes, look at something at least 20 feet away for at least 20 seconds. The ciliary muscles return to their resting state. The tear film, which depletes with reduced blinking during concentrated screen work, has time to recover.
The rule works. The problem is compliance under normal work pressure. People know the rule and do not do it because there is always something more pressing. An automated break timer set to fire every 20 minutes is substantially more effective than trying to remember. One that pauses automatically during video calls is more useful still, since break reminders during a meeting are disruptive rather than helpful.
4. Increase text size rather than moving closer
The common advice to sit further from the screen often backfires. If text becomes harder to read at a greater distance, you compensate by leaning forward anyway, ending up with forward head posture and the same close viewing distance. The right fix is to increase display scaling or font size until comfortable legibility is possible at a natural arm's length (around 50 to 70 cm). Most operating systems support display scaling without image quality loss on modern high-resolution screens.
The same logic applies to monitor position. The top of the screen should sit at or slightly below eye level, with the screen tilted slightly back. Looking slightly down reduces lid aperture, which slightly reduces tear film evaporation and is easier on the neck over a long session.
5. Reduce glare from windows and overhead lighting
Glare from a window reflected on the monitor surface, or from overhead fluorescent fixtures hitting the screen directly, forces the pupils into extra adjustment effort and degrades the clarity of what you are reading. A matte screen protector or anti-glare filter helps with direct surface reflections. For overhead lighting, a desk lamp positioned to light the work surface without hitting the screen face-on is usually preferable to overhead fluorescents, which create more diffuse glare on monitor surfaces.
If your desk puts a window directly behind or in front of you, adjusting the monitor angle or closing blinds during peak daylight hours makes a meaningful difference.
6. Check for PWM flicker if reducing brightness makes symptoms worse
This step applies to a subset of users on specific monitor hardware, but it is relevant enough to include because it is the explanation for a counterintuitive symptom pattern: eye strain and headaches that get worse as you reduce screen brightness, the opposite of what most guidance predicts.
Many monitors control backlight intensity through pulse-width modulation (PWM): rapidly switching the backlight on and off rather than smoothly adjusting its power. At lower brightness settings, the flicker duty cycle becomes more aggressive. For users whose visual systems are sensitive to this, the result is increased eye fatigue and frontal headaches at exactly the settings they thought would help.
How to check: Open your phone's camera, switch to slow-motion video mode, and point it at your monitor while it is running at a lower brightness setting. If you see horizontal banding or a flickering pattern in the recording, your monitor is using PWM at that brightness level.
What to do: Keep hardware brightness above the PWM activation threshold (often above 50 to 60% on affected monitors) and use software brightness control to reduce the perceived screen intensity without touching the hardware backlight. This is the approach Circadian Shield's software dimming feature is specifically designed for. See monitor brightness and eye strain for the full explanation.