Photosensitive epilepsy

What is photosensitive epilepsy?

People with photosensitive epilepsy have seizures that are ‘visually provoked’. These seizures are a type of reflex seizure. This means they happen every time you encounter a specific trigger. This could be flashing or flickering lights, or patterns.

Most people who have photosensitive epilepsy also have seizures that are triggered by other things too. But some people will only have visually-provoked seizures.

Around 8 in 10 people with photosensitive epilepsy have generalised tonic-clonic seizures. Other types of photosensitive seizure are also possible, including myoclonic and absence seizures.

How common is photosensitive epilepsy?

Photosensitive epilepsy affects around 1 in 4000 people overall. Not everyone with epilepsy has photosensitive epilepsy. Only around 3 to 5 in every 100 (3 to 5%) people with epilepsy will have photosensitive epilepsy.

Women are more likely to have photosensitive epilepsy than men. Studies suggest that around twice as many females have photosensitive epilepsy as males.

Genetics may also be involved in photosensitive epilepsy. For example, you may be more likely to have photosensitive epilepsy if a parent also has it. But this is not always the case.

Can you grow out of photosensitive epilepsy?

Some people with photosensitive epilepsy may eventually stop having photosensitive seizures.

Photosensitive epilepsy is more likely to affect younger people. Many people who develop it are under 20 years of age. It often begins around the time of puberty.

For some people, it may improve as they get older. For others, it does not go away. People with a family history of photosensitive epilepsy are more likely to continue having seizures as they grow older.

What types of epilepsy are linked to photosensitive seizures?

Photosensitive seizures are more common in some types of epilepsy and epilepsy syndromes. Click on each condition below to find out more about a specific epilepsy:

• Juvenile myoclonic epilepsy
• Childhood absence epilepsy
• Epilepsy with generalised tonic-clonic seizures alone
• Juvenile absence epilepsy
• Myoclonic epilepsy in infancy
• Epilepsy with eyelid myoclonia (Jeavons syndrome)
• Lennox Gastaut syndrome
• Dravet syndrome

How do I know if I have photosensitive epilepsy?

Doctors can use an EEG test to detect if you are photosensitive. EEG stands for electroencephalogram. This test records electrical activity in the brain.

During the EEG, you will be asked to look at flashing lights and/or other types of visual stimuli such as structured patterns (bars). The EEG can record if these cause specific changes in your brain activity. If they do, it may mean you have photosensitive epilepsy.

If you notice any symptoms or seizure patterns associated with exposure to lights, note down what happens. You can speak to your GP or epilepsy specialist and they can refer you for further tests if necessary.

We have a free seizure diary that you can use to track changes to your seizures or symptoms.

How to check your medical records

If you have a diagnosis of epilepsy, you might have already had an EEG. Your medical record will say if you have been tested for photosensitive epilepsy.  Your GP or epilepsy specialist can give you this information. Or, you can find out by accessing your medical records online.

What can trigger photosensitive seizures?

There are many possible visual triggers for photosensitive epilepsy. They can be different for each person. Not every trigger will affect every person with photosensitive epilepsy.

Flashing or flickering lights

Flashing lights are a common trigger for people with photosensitive epilepsy. A light may be most likely to trigger a seizure if it flashes or changes colour at a rate between 10 and 25 flashes per second. But some people can be sensitive to lights that flash as slow as 3 times a second or as fast as 60 times per second.

The light is more likely to trigger a seizure if it reaches both eyes. This is why covering one eye can help to prevent light-stimulated seizures.

A flashing light may also be more likely to trigger a seizure in some people if it:

• Is very bright
• Takes up at least 10% of the area that you can see. This is called your visual field
• Lasts for at least half a second

The rate that a light flashes is sometimes measured by Hertz. If a light flashes 25 times per second, it may be written down as 25 Hertz or 25 Hz.

What types of lighting can cause seizures?

Many types of flashing lights can cause photosensitive seizures for some people. These include:

•  Strobe lighting at concerts or in clubs
•  Rapid camera flashes
•  Flickering light bulbs
•  Some Christmas lights and fireworks

Can bicycle lights cause seizures?

Red and white bicycle lights used in the UK are covered by a specific law for road vehicles. The law says that these lights must flash between 1 and 4 flashes a second (1 to 4 Hz). If a light complies with this law, it is unlikely to cause a problem.

However, other countries have different rules. Bike lights that are not made for the UK may flash at a different frequency.

Can LED and strip lights cause a seizure?

Standard light bulbs do not usually trigger photosensitive seizures. Fluorescent strip or tube lights are also usually fine. But these lights might cause problems if they are faulty. Or, if the wrong type of bulb is used, causing the light to flicker.

LED lights do not seem to be a common trigger for people with photosensitive epilepsy, unless they are flashing. But we do not have enough research to be sure.

What are UK regulations for lighting at work?

UK workplace regulations require that employers consider employees’ needs. The Health and Safety Executive has guidance for lighting at work. Employers should provide appropriate lighting or adequate control measures to prevent the risk of seizures.

Find out more about workplace guidelines and your rights if you have epilepsy. Or contact our Helpline on 0808 8005050 to talk to one of our trained advisors.

Sunlight and rotating blades

Other triggers for photosensitive epilepsy include moving sunlight. For example:

• Sunlight through trees, hedges, or railings, especially if seen from a moving vehicle
• Sunlight through slatted blinds
• Sunlight reflected off moving water or off snow
• Dappled sunlight through leaves

Some types of rotating blades might also trigger seizures, for example:

• Helicopter blades rotating at a fast speed
• Smaller turbines and blades that rotate quickly. These can potentially trigger a seizure if they create a shadow or a flicker effect with the light. This risk decreases the further away you are

Large wind turbines are unlikely to trigger a seizure as their blades rotate at a slow rate.

Patterns and colour changes

Repetitive patterns such a strong stripes or checks can trigger seizures. For example:

• Repeating high contrast patterns such as black and white stripes or zig zags
• A moving escalator
• Strong patterns or colour changes in some television programmes, video or electronic games. Particularly when moving from a strong red colour to a very different colour, like blue

Patterns on screens

Research suggests that patterns on an electronic screen can be more likely to trigger a seizure for some people if:

• There are at least 5 to 8 pairs of repeating stripes
• They are very bright and cover a larger portion of your field of vision
• They appear for longer than half a second
• They vibrate, reverse colours or flicker

Online content, TVs, and video games

Content with flashing imagery or animated patterns can potentially trigger seizures:

• Online content in social media videos and GIFs
• On television
• In video games, including 3D games and virtual reality games
• Films at the cinema. Although this is less likely due to the dimmer screen lighting used in cinema theatres

We talk more about how to reduce your risk from this type of content below.

How is photosensitive epilepsy treated?

The most common way to treat photosensitive epilepsy is with epilepsy medicines. This can lower the risk of having a seizure. If your epilepsy is well controlled by medicines, you are also less likely to have photosensitive seizures.

Many people find the most effective way of preventing or reducing seizures is to:

• Take epilepsy medicines, and
• Avoid seizure triggers

Can glasses help with photosensitive epilepsy?

There is some evidence that wearing glasses with dark lenses may protect you from triggers on screens and in the natural environment. The dark lenses help to reduce brightness. Polarised lenses may also help. This is because they decrease brightness. But they may not be completely protective.

Wearing hats with a brim can also help when outside.

Can Z1 lens glasses help reduce seizures?

People with photosensitive epilepsy may benefit from glasses with coloured lenses. Particularly blue coloured lenses. Studies show that wearing glasses with a dark cobalt blue lens, called a ‘Z1 lens’, can help prevent photosensitive seizures.

These lenses work by reducing the total amount of light and filtering out red light. Red is the colour most likely to trigger a seizure. These glasses are not suitable for driving. This is because Z1 lens glasses block out red light it can be hard see red or amber lights.

You can buy coloured glasses online or from an optometrist. Different people find different types and strength of colour effective. You might want to try out a few different types first.

It might also be worth asking your epilepsy specialist or an optometrist if these glasses could be helpful for you.

Can I drive with photosensitive epilepsy?

Many people with epilepsy can drive, if they meet the driving rules for their type of seizures.

Find out more about driving rules for epilepsy.

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Thank you to Professor Stefano Seri, Consultant Clinical Neurophysiologist at Birmingham Women’s and Children’s NHS Foundation Trust, and our health information volunteers, for their help contributing to and reviewing this content.

Find out more about how you can help us create our health information.