Can flashing lights, music or a hot shower cause seizures? The science behind reflex epilepsy

Imagine a young man who looks forward to his morning shower. But almost every time he pours hot water over his head, something strange happens. For a few seconds, he becomes blank and unresponsive.

Sometimes his eyes turn to one side; sometimes his body stiffens. Within a minute, he is completely normal again. His family initially thinks he is fainting or perhaps simply reacting badly to hot water. But the episodes keep recurring, almost exclusively during hot showers.

This is hot-water epilepsy, one of the most fascinating forms of reflex epilepsy.

In reflex epilepsy, a seizure is repeatedly triggered by a particular stimulus or activity. Unlike common seizure triggers such as sleep deprivation, alcohol or emotional stress, which can make seizures more likely in many people, the trigger in reflex epilepsy is unusually specific and reproducible. It can be a flashing light, reading, eating, music, thinking, or even bathing in hot water.

When the brain responds abnormally to an ordinary activity

Our brains constantly process sensory information and perform complex activities. In a person with an epilepsy-prone brain network, activating a particular network can occasionally provoke abnormal electrical activity, a seizure.

Reflex seizures can be focal or generalised, depending on the underlying epilepsy. Sometimes the person has seizures only when exposed to the trigger; in others, spontaneous seizures occur as well.

Hot-water epilepsy

This is particularly interesting in India. It has been reported from southern India for decades. The typical episode occurs while bathing or when hot water is poured over the head. Some patients develop impaired awareness; others may have more obvious seizures.

The good news is that avoiding very hot water and using lukewarm water can help some patients, although trigger avoidance alone is not always sufficient. Some people require antiseizure medication.

Photosensitive epilepsy

Flashing or rapidly changing lights can provoke seizures in susceptible individuals. Television, video games, strobe lights, certain visual patterns, and some social media or online content can occasionally be triggers.

Photosensitivity is particularly relevant in children and adolescents. Importantly, seeing flashing lights does not mean that everyone with epilepsy will have a seizure. Photosensitivity affects only a subset of people with epilepsy.

Practical precautions include increasing the distance from a screen, watching in a well-lit room, avoiding prolonged exposure to provocative flashing patterns, and covering one eye if a flashing stimulus is encountered unexpectedly. Medical evaluation is advisable if visually triggered episodes occur.

Music can trigger a seizure

This sounds almost unbelievable: musicogenic epilepsy is a rare condition in which particular music can provoke seizures. Interestingly, the trigger is often not simply a loud sound. It may be a particular melody or piece of music that has strong emotional significance to the person. Temporal-lobe networks involved in auditory and emotional processing are frequently implicated.

Eating can trigger seizures

Some people develop seizures specifically while eating. This is called eating epilepsy. It is rare. The seizures are usually focal-onset and commonly involve impaired awareness. In some people, the trigger may relate to chewing, swallowing, the sight or smell of food, or the complex brain activity associated with eating.

Can reading or even calculating trigger seizures?

Yes. Reading epilepsy is a rare form in which reading consistently provokes seizures. A person may initially notice repetitive jerking of the jaw or facial muscles while reading, which can sometimes progress to a generalized seizure.

Other unusual reflex seizures have been reported with writing, speaking, performing calculations, thinking, specific movements, touching certain body areas and startle. These examples demonstrate just how specifically epilepsy can involve particular brain networks.

When should you see a neurologist?

Don't ignore an episode simply because it happens only in one situation.

Seek neurological evaluation if you repeatedly experience:

• Brief loss of awareness during a particular activity 

• Repetitive jerking or unusual movements triggered by an activity 

• Sudden staring or unresponsiveness 

• Unexplained confusion after an episode 

• Recurrent episodes triggered by flashing lights 

• Unusual sensations, smells, sounds or emotions immediately before an episode 

• A seizure during bathing, eating, reading or another reproducible activity 

A neurologist may recommend an EEG, sometimes with the suspected trigger under controlled conditions, and an MRI brain when appropriate. The objective is not simply to identify the trigger but to determine what type of epilepsy is present and whether there is an underlying brain abnormality.

Can reflex epilepsy be treated?

Yes, and the outlook is often encouraging. Treatment depends on the type of epilepsy, frequency and severity of seizures, and whether seizures occur spontaneously.

For some people, avoiding or modifying the trigger may substantially reduce seizures. For example, using lukewarm rather than very hot water may help in hot-water epilepsy. Others require antiseizure medication. The choice depends on the seizure type and epilepsy syndrome and should be individualized by a neurologist.

If seizures remain uncontrolled despite appropriate medication, particularly in focal epilepsy, specialist epilepsy-centre assessment is important. Epilepsy surgery or other advanced treatments can be highly effective in carefully selected patients with drug-resistant epilepsy.

A trigger is not the same as a cause

This is an important distinction. Sleep deprivation, stress, fever and alcohol can increase seizure susceptibility in many people with epilepsy. But in reflex epilepsy, a particular stimulus repeatedly and specifically precipitates the seizure.

And having a reflex trigger does not mean that the person is psychologically weak or "imagining" the problem. The seizure is caused by abnormal electrical activity in the brain.

So, if a shower, a song, a meal, a video game or even a mathematics problem repeatedly causes brief, stereotyped episodes of altered awareness or abnormal movements, don't dismiss it as strange behaviour. The brain may be telling you something. And sometimes, the most unusual clue is the one that leads to the correct diagnosis.

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.