Photosensitive Epilepsy
Photosensitive Epilepsy Triggers
Sunlight strobing through the trees on a drive. A ceiling fan turning under a bright light. A burst of camera flashes at a birthday party. For someone with photosensitive epilepsy, everyday moments like these can bring on a seizure.
Knowing which lights and patterns cause trouble, and which usually don't, makes it easier to plan ahead and say yes to more.
Common Triggers
Lights That Can Trigger a Seizure
No one fully understands why some brains react to light this way, but the triggers are well known. Flashes between 16 and 25 per second are the most likely to cause a seizure, though some people react to a wider range (Epilepsy Society).
- Flashing or flickering light: strobes, disco lights, fireworks and faulty fluorescent bulbs
- Screens: TVs, computers, phones and movie screens, especially fast, flashing content
- Video games and VR headsets, which can fill most of your field of view
- Bright or reflected light, like sun glare off snow, water or a mirror
- Light broken into stripes, like sunlight through blinds, railings or a row of trees
- Camera flashes, bike lights and holiday lights, especially against a dark background
Patterns and motion
High-contrast patterns can be triggers too, especially stripes, checks and polka dots, and even more so when they move. Think ceiling fans, escalators, propellers and wind turbine blades.
What raises the risk
Being tired, stressed or excited can make a seizure more likely, and so can sitting close to a screen or watching in a dark room.
What Usually Isn't a Problem
Triggers vary from person to person, but these tend to be lower risk:
- LCD and other modern flat screens, especially ones with a high refresh rate
- Interactive whiteboards
- Lights that flash fewer than three times per second
Lower risk isn't no risk, so it still helps to know your own triggers.
Everyday Prevention
Simple Ways to Lower the Risk
A few small habits go a long way, at home and wherever the day takes you.
At Home
- Watch TV in a well-lit room, far enough back that the screen doesn't fill your view
- Lower screen brightness and turn off autoplay for videos and GIFs
- Take regular screen breaks, and check games for seizure warnings
Out and About
- Wear polarized sunglasses to cut glare off water and snow
- Wear glasses with Z Blue lenses to filter seizure-triggering light
- On drives, watch for sunlight flickering through trees and fences
Concerts and Movies
- Check ahead for strobe or flashing-light warnings
- Sit farther back from the stage or screen
- Bring your epilepsy glasses (here's how they help at movie theaters)
If You're Exposed to a Trigger
In the moment: If a flashing light catches you off guard, cover one eye completely with your hand and turn away. The Epilepsy Society recommends this rather than closing your eyes. Then move somewhere with steadier light if you can.