Photosensitivity and Seizures

Seizures in photosensitive people may be triggered by exposure to some of the following situations:

  • Television screens or computer monitors due to the flicker or rolling images.
  • Certain video games or TV broadcasts containing rapid flashes or alternating patterns of different colors.
  • Intense strobe lights like visual fire alarms.
  • Natural light, such as sunlight, especially when shimmering off water, flickering through trees or through the slats of Venetian blinds.
  • Certain visual patterns, especially stripes of contrasting colors.
  • Some people wonder whether flashing lights on the top of buses or emergency vehicles may trigger seizures in people with photosensitive epilepsy too.

Not all televisions, video games, computer monitors, and strobe lights trigger seizures. Even in predisposed individuals, many factors must combine to trigger the photosensitive reaction. Examples include:

  • Frequency of the flash (that is, how quickly the light is flashing)
  • Brightness
  • Contrast with background lighting
  • Distance between the viewer and the light source
  • Wavelength of the light
  • Whether a person’s eyes are open or closed

The frequency or speed of flashing light that is most likely to cause seizures varies from person to person. Generally, flashing lights most likely to trigger seizures are between the frequency of 5 to 30 flashes per second (Hertz).

The likelihood of such conditions combining to trigger a seizure is small.

  • Check with your doctor if you are concerned about flashing lights triggering seizures. Chances are that your medical records will indicate how you responded to flashing lights during the electroencephalogram (EEG), a test done routinely in most people with epilepsy.
    • During this test, sensors are attached to the person’s scalp to monitor the electrical activity of the brain in various conditions, including light stimulation generated by a strobe positioned in front of the eyes.
    • An abnormal response to various frequencies of flashing lights indicates the presence of photosensitivity.
  • If you have not been diagnosed with epilepsy or have not had an EEG, ask your doctor about ordering one for you or consult a local neurologist.
  • Finding out if you are photosensitive can be helpful if your daily activities include risks such as intense videogame playing.

Reviewed By:

Elaine Wirrell MD

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