Flashing Lights,
TV Shows, &
Photosensitive Epilepsy
Mindy Hung
Medical Writer

Television programs have come under stricter regulation in Great Britain and Japan after causing seizures in children. The illness, a form of epilepsy known as photosensitivity, is triggered by the flashing lights and quickly alternating shots found in many shows and commercials.
But while researchers have long known that bright, regular flares can provoke epileptic episodes, photosensitivity has gained a higher profile within the last 20 years as new triggers for the illness crop up with each new piece of media technology that comes along. Indeed, an increase in the number of stimuli--anything from fluorescent lighting to video and virtual reality games--has led to debate as to whether measures similar to those adopted in the UK should be enforced in the United States.
Trigger Happy
Epileptic seizures can occur when quick flashes of light cause neurons to fire up and produce abnormal signals within the brain. These flashes may come from almost any source.
Even seemingly benign scenes, such as sunlight reflecting off of waves, for example, may trigger episodes. The strobe effect caused by light passing between buildings and telephone poles and the blinking of ambulances and fire trucks can provoke attacks. Flashing television and video game screens can yield similar results.Indeed, what these settings have in common is their regular and swift movement from darkness to brightness. These bursts of light occur with a speed and frequency that does not give the eyes (or anything else) much time to adjust, let alone to process the image. Often, they bewilder even people who do not suffer from epilepsy.
Light Regulation
Professor Graham Harding of Britain's Aston University, the world's foremost authority on photosensitivity, is one of the people behind the UK's push to regulate television and commercials. Harding has set out guidelines that include warnings for editors and game designers against centering bars or black and white patterns on screens. He includes information on the number of frames of contrast that must follow one another and the patterns that most often produce epileptic seizures. Red, he notes, is especially provocative, as are oscillating bars or grating in highly contrasting colors (for instance, black and white).
But Harding also suggests that people who may suffer from photosensitivity may help themselves by simply backing away from the television set. Sitting too close causes problems: The hundreds of cycling tiny bands that make up the TV picture only become perceptible at distances of less than 1 meter (3 1/2 feet).
Rage Against the Machine
Indeed, it may fall to those with photosensitivity to help themselves, because no attempt has generally been made to minimize blinking lights and jarring video flashes. Indeed, these effects have only become more widespread and fashionable in recent years.
Designers, programmers, and video editors have even been choosing these effects in a deliberate attempt to cause disorientation. After all, many people enjoy strobes in nightclubs, which are designed to dazzle and heighten confusion. The lighting in amusement park rides and casino marquees also produces similar effects.But while these displays are supposed to be fun and exciting, the new sophistication and scope of technology has triggered reactions in people--epileptics and non-epileptics alike--that no one ever anticipated.
In addition to the widely reported "cartoon illness" that provoked epileptic seizures in 685 Japanese children in 1997, shaky camera work in the recent hit movie Blair Witch Project has caused many people to vomit after becoming nauseous and dizzy. Similar symptoms have also plagued fans of the computer game Doom. These problems arise because the brain has difficulty adjusting to the game environment. The game Doom, for instance, which puts players through bewildering and colorful three-dimensional battles, shifts its display just slightly more slowly than the speed at which the brain would perceive such objects in a similar situation in real life.
The difference between the game and real life is that in a game you don't really move. The pictures adjust so that you feel like you are spinning around. But the pictures create this illusion slightly more slowly than the same experience would occur if it were real. When a player emerges from a Doom marathon, this slow adjustment rate (the "virtual rate") is thrown into conflict with the real rate of the real world.
When a person stops playing the game, the result is akin to motion sickness; the difference in speed causes vision to blur and even makes some people throw up, all because the brain has become confused in its reactions.
A Safe Distance
New technologies and new media become more sophisticated and widespread every day, but little time has been spent considering the possible effects these gadgets and games may have on people--with epilepsy and without. Few take time to consider the impact of fluorescent lights or flashing bulbs on those around them.
And those with photosensitive epilepsy bear most of the brunt. With products springing up every day, they must approach every new television commercial, movie, and computer program with caution.
Aug.1999 @ 1999 by Medscape Inc. All rights reserved.
Mindy Hung is a staff member at Medscape Professional. She has also written for the Winnipeg Free Press and Salon.