PWM dimming and migraine: what is known and what isn't

Updated 2026-11-02

Quick answerPWM dimming switches a light on and off very fast to make it look dimmer. In a 2024 lighting study, PWM-like square-wave modulation was the most annoying waveform and was visible to most people even at 4,800 Hz. That study used an LED, not a screen. No browser or extension can change a screen's PWM.

Evidence

  • Miller et al. 2024: rectangular 100%-modulation waves were the most annoying; at 10,000 Hz they were no more visible than steady light.
  • People with migraine were more sensitive at higher frequencies than people without migraine.

What we don't know

  • We found no peer-reviewed study showing that dimming in software instead of with the brightness keys helps people with migraine. It's plausible on PWM panels, but unproven.
  • Panel PWM behavior varies by model; check independent measurements for your device.

FAQ

Can Migraine Mode turn off PWM?

No. PWM is controlled by the display hardware and firmware. The extension only applies CSS filters to web pages.

Sources

  • Miller NJ, Irvin L, Royer M, Strachan C. Visibility and annoyance of the phantom array effect varies with age and history of migraine. Lighting Res Technol, 2024. Link

Not a medical device and not medical advice. Migraine Mode is a screen-comfort tool: it does not diagnose, treat, cure or prevent migraine or any other condition, and it does not replace a doctor. Its settings are based on studies of light, colour, flicker, patterns and motion; the extension itself has not been clinically tested. When to see a doctor.