Photosensitive epilepsy is a fairly rare form of epilepsy that can trigger a seizure on exposure to certain types of flashing or flickering lights or patterns. Only a small percent of epilepsy sufferers are photosensitive, although the condition may also manifest itself in people with no previous history of epilepsy. It is more common in younger people.

It is believed to be the cause behind the 1997 Pokémon seizures in Japan that resulted in the brief hospitalization of hundreds of children who had been watching the enormously popular show.