question: How exactly do rapidly blinking lights cause seizures?
comment: It has to do with bright flashing lights being too much for the brain to handle. The contrast between bright and dark at fast speeds overstimulates your brain. You can test this by staring at flashing bright lights for an extended period; it will most likely give you a headache.
passages: In some epileptics, flickering or flashing lights, such as strobe lights, can be responsible for the onset of a tonic clonic, absence, or myoclonic seizure. This condition is known as photosensitive epilepsy and, in some cases, the seizures can be triggered by activities that are harmless to others, such as watching television or playing video games, or by driving or riding during daylight along a road with spaced trees, thereby simulating the "flashing light" effect. Some people can suffer a seizure as a result of blinking one's own eyes. Contrary to popular belief, this form of epilepsy is relatively uncommon, accounting for just 3% of all cases.
   A routine part of the EEG test involves exposing the patient to flickering lights to attempt to induce a seizure, to determine if such lights may be triggering a seizure in the patient, and to be able to read the wavelengths when such a seizure occurs.
  
  In rare cases seizures may be triggered by not focusing.
  
  Section::::Head injury.
   Photosensitive epilepsy is an abnormal sensitivity of the brain to visual stimuli and is the most common trigger in reflex seizures. Reflex seizures can be induced by both flickering or non-flicking light, television, video games, or other visual patterns. Most people who have photosensitive epilepsy are sensitive to specific patterns for visual stimuli. Visual stimuli of a particular frequency (15-25 flashes/second), wavelength (red light at 660-720 nm), and at high contrast have been shown to have a higher risk of inducing seizures in people who are photosensitive. In addition, emotional excitement, fatigue, or length of exposure can all effect the risk of seizures.
   The visual trigger for a seizure is generally cyclic, forming a regular pattern in time or space. Flashing lights or rapidly changing or alternating images (as in clubs, around emergency vehicles, near overhead fans, in action movies or television programs, etc.) are examples of patterns in time that can trigger seizures, and these are the most common triggers. Static spatial patterns such as stripes and squares may trigger seizures as well, even if they do not move. In some cases, the trigger must be both spatially and temporally cyclic, such as a certain moving pattern of bars.
   Those with photosensitive epilepsy can have seizures triggered by flashing lights. Other precipitants can trigger an epileptic seizure in patients who otherwise would be susceptible to spontaneous seizures. For example, children with childhood absence epilepsy may be susceptible to hyperventilation. In fact, flashing lights and hyperventilation are activating procedures used in clinical EEG to help trigger seizures to aid diagnosis. Finally, other precipitants can facilitate, rather than obligately trigger, seizures in susceptible individuals. Emotional stress, sleep deprivation, sleep itself, heat stress, alcohol and febrile illness are examples of precipitants cited by patients with epilepsy. Notably, the influence of various precipitants varies with the epilepsy syndrome. Likewise, the menstrual cycle in women with epilepsy can influence patterns of seizure recurrence. Catamenial epilepsy is the term denoting seizures linked to the menstrual cycle.
   When functioning correctly, mains-powered fluorescent lighting has a flicker rate sufficiently high (twice the mains frequency, typically 100 Hz or 120 Hz) to reduce the occurrence of problems. However, a faulty fluorescent lamp can flicker at a much lower rate and trigger seizures. Newer high-efficiency compact fluorescent lamps (CFL) with electronic ballast circuits operate at much higher frequencies (10–20 kHz) not normally perceivable by the human eye, though defective lights can still cause problems.
  
  Section::::Diagnosis.
   Recent studies have shown that specific neurological findings have affected idiopathic occipital lobe epilepsies. Occipital lobe seizures are triggered by a flash, or a visual image that contains multiple colors. These are called flicker stimulation (usually through TV) these seizures are referred to as photo-sensitivity seizures. Patients having experienced occipital seizures described their seizures as featuring bright colors, and severely blurring their vision (vomiting was also apparent in some patients). Occipital seizures are triggered mainly during the day, through television, video games or any flicker stimulatory system. Occipital seizures originate from an epileptic focus confined within the occipital lobes. They may be spontaneous or triggered by external visual stimuli. Occipital lobe epilepsies are etiologically idiopathic, symptomatic, or cryptogenic. Symptomatic occipital seizures can start at any age, as well as any stage after or during the course of the underlying causative disorder. Idiopathic occipital epilepsy usually starts in childhood. Occipital epilepsies account for approximately 5% to 10% of all epilepsies.
   Some people with PSE, especially children, may exhibit an uncontrollable fascination with television images that trigger seizures, to such an extent that it may be necessary to physically keep them away from television sets. Some people (particularly those with cognitive impairments, although most people with PSE have no such impairments) self-induce seizures by waving their fingers in front of their eyes in front of bright light or by other means.
   Photosensitive reflex epilepsy is usually treated with both lifestyle changes and anti-epileptic medications. Some lifestyle modifications that may be recommended are limiting the amount of time one is exposed to television or screens, watching television in a bright well-lit room at a distance of at least 2 meters, and avoiding television or video games when tired. LCD TV screens or Televisions with higher refresh rates (100 Hz) cause less flickering and thus lower the likelihood of a seizure. In addition, special blue lens Z1 glasses have been shown to reduce seizures in many people with photosensitive reflex epilepsy.
   In March 1997, the 25th episode of an anime series called "YAT Anshin! Uchū Ryokō" caused a similar incident, when a reported four children were taken to hospitals by ambulances after viewing a scene with red and white flashing colours.
   Later studies showed that 5–10% of the viewers had mild symptoms that did not need hospital treatment. 12,000 children reported mild symptoms of illness, but their symptoms more closely resembled mass hysteria than a grand mal seizure. A study following 103 patients over three years after the event found most of them had no further seizures. Scientists believe the flashing lights triggered photosensitive seizures in which visual stimuli like flashing lights can cause altered consciousness. Although about 1 in 4,000 people are susceptible to these types of seizures, the number of people affected by this "Pokémon" episode was unprecedented.
   Section::::Signs and symptoms.:Triggers.
  
  Stimuli that cause reflex seizures can be categorized as either intrinsic or extrinsic. For a give person, the stimulus that triggers may be intrinsic, extrinsic, or a combination of both.
  
  Section::::Signs and symptoms.:Triggers.:Extrinsic stimuli.
  
  Extrinsic stimuli are sensory stimuli that originate from the person's environment. Similar to intrinsic stimuli, extrinsic stimuli can be divided into two categories, either simple or complex. Examples of simple extrinsic stimuli include flashing lights or touch while complex extrinsic stimuli can include music, language, reading, or stimulation from eating. Some of the more common types of reflex epilepsy include light and music.
   Rapidly flashing lights may be dangerous for people with photosensitive epilepsy or other nervous disorders. It is thought that one out of 10,000 adults will experience a seizure while viewing such a device; about twice as many children will have a similar ill effect.
  
  Section::::Other information.:Regulation.
  
  Mind machine devices are legally available throughout the United States from many sources.
   About 6% of those with epilepsy have seizures that are often triggered by specific events, known as reflex seizures. A number of epilepsy syndromes, known as reflex epilepsies, have seizures that are only triggered by specific stimuli. Common triggers include: flashing lights and sudden noises.
   Later studies showed that 5–10% of the viewers had mild symptoms that did not need hospital treatment. Twelve thousand children who were not sent to hospital reported mild symptoms of illness; however, their symptoms more closely resembled mass hysteria than a grand mal seizure. A study following 103 patients over three years after the event found that most had no further seizures. Scientists believe that the flashing lights triggered photosensitive seizures in which visual stimuli such as flashing lights can cause altered consciousness. Although approximately 1 in 4,000 people are susceptible to these types of seizures, the number of people affected by the "Pokémon" episode was unprecedented.
   There are many hazards that people with epilepsy, including those whose seizures are fully controlled by medication, face in the workplace. Those with active seizures face the obvious risk of loss of consciousness or muscle control, and those with side effects face diminished concentration or physical strength. Some of the hazards include:
  
  BULLET::::- Working near a body of water, a high-voltage power line, or at extreme heights
  
  BULLET::::- Working with machines, equipment, or hazardous chemicals or materials that require care in their usage
  
  BULLET::::- The supervision of other persons, where any lapse in such supervision may be hazardous
  
  Section::::Issues.:Transportation.
   BULLET::::- Hemorrhagic stroke can occasionally present with seizures, embolic strokes generally do not (though epilepsy is a common later complication); cerebral venous sinus thrombosis, a rare type of stroke, is more likely to be accompanied by seizures than other types of stroke
  
  BULLET::::- Multiple sclerosis may cause seizures
  
  Electroconvulsive therapy (ECT) deliberately sets out to induce a seizure for the treatment of major depression.
  
  Section::::Mechanism.
   Focal aware seizures are often called "auras" when they serve as a warning sign of a subsequent seizure. Regardless, an "aura" is actually a seizure itself, and such a focal seizure may or may not progress to a focal impaired awareness seizure. People who experience only focal aware seizures may not recognize what they are, nor seek medical care.
  
  Section::::Signs and symptoms.:Focal seizures.:Focal impaired awareness seizures.
   Contrary to other forms of photosensitive epilepsies that are sensitive only to flickering lights, patients with Jeavons syndrome are also sensitive to bright, non-flickering lights. This is probably due to the enhancing effect of bright light on the sensitivity of eye closure.
  
  Section::::Signs and symptoms.:Self-induction in Jeavons syndrome.
  
  Self-induced seizures in Jeavons syndrome are rare. Eyelid myoclonia is a seizure and not an attempt for self-induced seizures. These patients do not need to produce conditions of intermittent photic stimulation for self-induction. Simply closing the eyes would be more potent.
  
  Section::::Cause.
   Section::::Signs and symptoms.:Focal seizures.
   Section::::Types.
  
  As of 2017, focal seizures are split into two main categories, "focal onset aware", and "focal onset impaired awareness". What was previously termed a "secondary generalised seizure" is now termed a "focal to bilateral seizure".
  
  In focal onset aware seizures, a small part of one of the lobes may be affected and the person remains conscious. This can often be a precursor to a larger focal onset impaired awareness seizure. When this is the case, the focal aware seizure is usually called an aura.
   Section::::Society and culture.:Web design.
  
  As with video games, rapidly changing images or highly regular patterns such as flashing banner ads or irregular fonts can trigger seizures in people with photosensitive epilepsy. Two sets of guidelines exist to help web designers produce content that is safe for people with photosensitive epilepsy:
   Television has traditionally been the most common source of seizures in PSE. For people with PSE, it is especially hazardous to view television in a dark room, at close range, or when the television is out of adjustment and is showing a rapidly flickering image (as when the horizontal hold is incorrectly adjusted). Modern digital television sets that cannot be maladjusted in this way and refresh the image on the screen at very high speed present less of a risk than older television sets.
   Focal seizures are seizures that arise from a small area of the brain in one hemisphere. Focal seizures are divided into simple or complex focal seizures. Simple focal seizures do not involve the impairment of consciousness but instead may have motor, sensory, or autonomic manifestations. Complex focal seizures do involve impairment or loss of consciousness. Focal seizures are usually only seen in certain types of reflex epilepsies such as occipital lobe seizures in photosensitive occipital lobe epilepsies or temporal lobe seizures in musicogenic epilepsies. Focal seizures can be located only in the area of the brain responsible for the stimulus, spread to other areas of the brain, or even develop into a generalized seizure.
   BULLET::::- Photosensitive epilepsy - This is an epileptic reaction to flashing lights in susceptible persons, which can range in severity from an unusual feeling or involuntary twitch to a generalized seizure. This epileptogenic response can be triggered by lights flashing in the frequency range of 10–20 Hz, regardless of color. While individual light sources used on emergency vehicles generally have much lower flash rates than this, the Loughborough study suggests that such possibilities be minimized. It also notes that emergency workers may report distraction and eyestrain unrelated to epilepsy from working under the lights.
  