Screen flicker test
Many displays dim by switching the backlight on and off hundreds of times a second.
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The symptom
Strain that gets worse at night, on one device but not another, is the clue.
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What PWM means
Instead of lowering brightness, the backlight pulses. Faster pulsing is easier to tolerate.
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Why night is worse
The dimmer you set the screen, the longer the backlight stays off between pulses.
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Run the test
A flickering backlight breaks the motion into separate copies instead of a smooth trail.
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What to look for
Clear repeated edges suggest PWM. A smooth blur suggests steady, flicker-free dimming.
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Not everyone
Sensitivity varies widely. Migraine and dry eyes can make the same screen unbearable.
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What helps
Higher brightness usually shortens the off phase. Warm light and screen breaks help too.
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One honest limit
This shows whether flicker is visible to you, not the exact PWM frequency.
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Your turn
Run the pattern at full and low brightness, then compare your devices.
Photo: Tima Miroshnichenko / Pexels