Why does a concussion cause light sensitivity?
Researchers are still working out the exact cause; inflammation and changes in how brain cells signal are among the leading ideas.1 What’s clear is that the visual system and the brain’s pain pathways are closely connected. Light-sensing cells in the retina feed neurons that also carry head pain,3 so after an injury, light that used to be comfortable can hurt.
How long does it last?
Light sensitivity often improves as the brain recovers, but for a subset of people it lasts six months or longer, sometimes as part of post-concussion syndrome.1
Getting back to screens
Dizziness is common after a concussion too, and busy, scrolling screens can set it off; see screens and dizziness.
Most care teams recommend a gradual return to screens, guided by symptoms. Within whatever limits you’ve been given, a few things make screen time gentler:
- Lower the brightness and match it to the room.
- Enlarge text so you don’t have to lean in and strain.
- Take frequent breaks, and stop when symptoms build.
- Reduce glare from windows and overhead lights.
- Avoid flicker. Many screens pulse their backlight with PWM, especially at the low brightness you’re likely to use.
What makes a screen easier after a concussion?
- No PWM. DC dimming keeps the light steady when you turn it down.
- Warm, soft light. No harsh white glare.
- No dithering. A true 8-bit panel keeps pixels still.