Reflex epilepsies are a group of epilepsy syndromes in which a certain stimulus brings on seizures. The stimulus can be something simple in the environment or something more complex like reading, writing, doing arithmetic, or even thinking about specific topics.
The types of seizures that may occur are varied, but 85% are generalized grand mal seizures. Other seizure types include absence seizures (staring) and myoclonic seizures (jerking of the eyes, head, or arms). The most common form of reflex epilepsy is photosensitive epilepsy, in which flashing lights trigger seizures. These seizures are usually found to be primary generalized seizures. Occasionally, partial seizures (arising from a small portion of the brain) may also present as a reflex epilepsy.

Photosensitive epilepsy usually begins in childhood and is often (but not always) outgrown before adulthood. It is more common in children with a parent who is also sensitive to flashing lights. Other reflex epilepsies may occur at any age. They affect only a small percentage of people with epilepsy. People who have reflex epilepsies generally are developmentally normal and have normal findings on a neurological examination.
Recently, there has been great interest in the safety of video games for children or adults with epilepsy. Certain video games (as well as certain television shows and movies) can provoke seizures. Sleep deprivation and stress or excitement caused by playing the games for a long time should also be considered as potential provoking contributors. Seizures that are triggered by the flashing lights and changing patters of video games occur during the game. Seizures that occur later, after the person has finished playing, are not caused by the game.

An effective way to prevent most reflex epilepsy seizures is simply to avoid the stimulus that triggers them, but usually people with reflex epilepsies require medication because their seizure triggers are unavoidable in everyday life or they also experience seizures without detectable causes. Most seizures are well controlled with low doses of medication. Some people do outgrow their seizures, but the decrease in susceptibility may not happen for many years: 75% of people with photosensitive reflex epilepsy continue to have seizures after age 25 if not treated. Doctors and patients need to be careful not to stop treatment too early, to keep seizures from reappearing.