Strobe Light - Strobe Lights and Epilepsy

Strobe Lights and Epilepsy

Although extrememly rare, strobe lighting can trigger seizures in photosensitive epilepsy. An infamous event took place in 1997 in Japan when an episode of the Pokémon anime, Dennō Senshi Porygon, featured a scene that depicted a huge explosion using flashing red and blue lights, causing about 685 of the viewing children to be sent to hospitals. These flashes were extremely bright strobe lights. They involved mulitple colors with a strobe effect nearing 20Hz. Although 95% of the 685 just complained of dizziness, some were hospitalized. Organizers later said that they did not know about the threshold of strobing.

Most strobe lights on sale to the public are factory-limited to about 10-12Hz (Or 10-12 flashes per second) in their internal oscillators, although externally triggered strobe lights will often flash as frequently as possible. Studies have shown that the majority of people that are susceptible to the strobing effects can have symptoms at 15Hz-70Hz, albeit rare. Other studies have shown epileptic symptoms at the 15Hz rate with over 90 seconds of continuous staring at a strobe light. There have been no known seizures at or below the 8Hz (or 8 flashes per second) level. Most fire alarms in schools, hospitals, stadiums, etc strobe at a 2Hz rate, which is obviously completely safe.