Contents
- Introduction
- About photosensitive epilepsy
- About hertz (Hz)
- Diagnosing photosensitive epilepsy
- Ways to reduce the risk of seizures if you have photosensitive epilepsy
- Some possible seizure triggers for people with photosensitive epilepsy
- Computer and television screens
- Useful information and contacts
Introduction
The aim of this information is to tell you what photosensitive epilepsy is, who it affects and what might trigger a seizure if you have photosensitive epilepsy. There are also suggestions for reducing the risk of having a seizure.
About photosensitive epilepsy
Photosensitive epilepsy is a type of epilepsy, in which all, or almost all, seizures are triggered by flashing or flickering light. Both natural and artificial light may trigger seizures. Some patterns, like stripes or checks, can also trigger seizures for some people with photosensitive epilepsy.
Various types of seizure can be triggered by flashing or flickering light. These include tonic-clonic, absence, myoclonic and focal seizures. The most common is a tonic-clonic seizure. The seizure(s) will usually happen at the time of, or shortly after, looking at the trigger.
Around three in every 100 people with epilepsy have photosensitive epilepsy. It usually begins before the age of 20, most commonly between the ages of seven and 19. Photosensitive epilepsy affects more girls than boys.
Epilepsy Action has more information about epileptic seizures.
About hertz (Hz)
The word hertz (Hz) refers to how often something happens in a second. For example, it can mean the number of times something flashes or flickers in one second. It can also mean the number of times the scanning lines on televisions and computer monitors ‘refresh’ themselves in one second.
Most people with photosensitive epilepsy are sensitive to 16-25 Hz. Some people may be sensitive to rates as low as 3 Hz and as high as 60 Hz.
Diagnosing photosensitive epilepsy
If you have an epileptic seizure when looking at flashing or flickering lights or certain patterns, this is a sign that you may have photosensitive epilepsy.
Your doctor may ask you to have an electroencephalogram (EEG) test. This test records the electrical signals from your brain on an EEG machine. During the test, you will be asked to look at some flashing lights. If doing this changes the electrical signals in your brain, it may indicate that you have photosensitive epilepsy.
The person doing the test will usually try to stop the test before you actually have a seizure. However, there is a small risk that you will have a seizure when the test is done.
Epilepsy Action has more information about EEG tests and diagnosing epilepsy.
Ways to reduce the risk of seizures if you have photosensitive epilepsy
- Avoid looking at anything that you know may trigger a seizure.
- Avoid things that can increase your risk of having a seizure. These can include feeling tired or stressed, not having enough sleep and drinking alcohol.
- If you take epilepsy medicine, always take it as prescribed by your doctor.
- If you look at something that might trigger a seizure, don’t close your eyes. This could increase your risk of having a seizure. Instead, immediately cover one eye with the palm of your hand and turn away from the trigger. This reduces the number of brain cells that are stimulated and reduces the risk of a seizure happening.
We can provide references and information on the source material we use to write our epilepsy advice and information pages. Please contact our Epilepsy Helpline by email at helpline@epilepsy.org.uk.
Epilepsy Action would like to thank Professor G F A Harding, Emeritus Professor of Clinical Neurophysiology, Aston University and also Professor Stefano Seri, Professor of Clinical Neurophysiology at Aston University and Consultant at the Birmingham Children’s Hospital NHS Foundation Trust for their contribution to this information.
This information has been produced under the terms of The Information Standard.
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Updated March 2012To be reviewed March 2014
Comments: read the 18 comments or add yours
Comments
Are there any glasses that lessen the effects of strobe lights at a night club? Does covering one eye for the duration of a club session stop the effects ?
Hi Tom,
Covering one eye with the palm of your hand will stop seizures in most cases. But would this be practical for you to do this all night while at the night club? You could try an eye patch, as long as it keeps the lights out. There aren’t any glasses that we are aware of to stop the effect of flashing lights. Polarised lenses can stop the glare, but not the flickering or flashing of lights that can trigger seizures, in people with photosensitive epilepsy.
Advice and Information Team
My boyfriend has photosensitive epilepsy and the summer months are a total nightmare for him, as he always feels ill when he goes outside. He wears sunglasses and hats but it is awful. Does anyone know anymore abotu blue polarised sunglasses?
Hi, I dont know if you will be able to help me with this.....my son has been to a laser tag fun game centre twice recently, after the first time he got a headache, felt dizzy and sick, after his second visit, he had all the same symptoms as the first but was worse with a very high temperature, he couldn't stop shaking, although he was really hot and seemed a bit delirious?? I feel really bad now for not taking him to the doctors, but by the end of the following day, he was back to his normal happy self......do you think it could be the strobe lights that they use that seemed to affect him? Any kind of advice would be great, I have phoned the laser centre and they told me they haven't had any complaints from other parents, but in all fairness it only opened in February. Should I still take him to the doctors to get him tested for future reference? Kind Regards.
Hi Heidi
I certainly think it’s worth taking your son along to see his GP to discuss the symptoms that he had, even if it was a while ago. This way the doctor can decide if he needs to have tests for epilepsy. We can’t say if it was an epileptic seizure because of flashing lights, or not, as it’s such an individual condition. However, if he did have epileptic seizures because of flashing lights, they would have happened while he was in the laser tag fun game centre, or moments after seeing the lights flashing. Seizures that happen because of flashing lights are called photosensitive epilepsy. These seizures aren’t common and affect around three in every 100 people with epilepsy.
Whether your son has photosensitive epilepsy or not, the laser tag fun game centre could be advised that it would be good practice to place a warning for people with photosensitive epilepsy. That is if they use special effects such as strobe lighting.
Advice and Information Team
My son has had drop seizures, absences and 1 tonic clonic seizure. The drop seizures and the tonic clonic all seemed associated with watching his DVD'S. He stopped breathing and I had to do CPR on him once he had stopped fitting. He came very close to losing his life on that day.
Through your magazine i now know about photosensitive Epilepsy. Watching his DVDs through a flat screen TV and now being on Epilim seemed to have helped. I am interestedto learn if there are any glasses that could be worn to lessen the risk at the cinema or at home?
Hi Christine,
Thanks for your question. We regret there are no glasses available to help with photosensitive epilepsy.
We do have some general safety suggestions for photosensitive epilepsy on this webpage. This information includes safety suggestion for watching television or using a computer.
Hi I am a 61 year old woman. In the last 5 yrs or so I have been really sensitive to flashing lights, ceiling fans that have lights that cause a flickering affect and small stripes.I've never had a seizure but last weekend at the beach I had a spell that I felt like I was shaking inside and when I closed my eyes I saw a large white spot. My daughter told me that my eyes looked funny. Could this be an onset to photosensitive epilepsy?
Hi,
As you are worried about your symptoms it would be a good idea to talk to your family doctor. It's worth bearing in mind, though, that there could be other things causing your symptoms. And photosensitive epilepsy most commonly begins before the age of 20. However, if your family doctor believes it may be epilepsy, they will refer you to a neurologist. The neurologist may ask you to have a few tests, including the electroencephalogram (EEG) test. This test records the electrical signals from your brain on an EEG machine. During the test, you will be asked to look at some flashing lights. If doing this changes the electrical signals in your brain, it may indicate that you have photosensitive epilepsy.
Diane
Advice and Information Team
I have epilepsy but I'm not sure if its photosensitive. I will soon be taking on a career as a police officer and will have to drive a car with strobes on it. See the problem here? I have always somewhat suspected I was photosensitive but I want to know if it would be OK for me to turn on my old strobe at home and have a go at it for about 5 or 10 minutes to see if there's is any effect?
Hi. Only about three in every hundred people who have epilepsy, have photosensitive epilepsy. You would normally be told this when you are diagnosed. The EEG, which is routinely used in diagnosis, usually involves specifically testing for photosensitive epilepsy. So it is reasonably likely that you would already have been told, or already realised you had photosensitive epilepsy.
If you’re not sure, you could always check with your doctor or epilepsy nurse. This is a more advisable course of action than experimenting by yourself. I am assuming you currently have a driving licence. If you were to ‘test’ yourself and you had a seizure you would lose your driving licence.
Also there is a particular flash or flicker rate which is most likely to trigger seizures in people with photosensitive epilepsy, so the police siren may well not be within that range.
I hope the career goes well.
Cherry
Advice and Information Team
Hi my daughter is 8 months and started having seizures aged 2 days. She was retrospectively diagnosed with benign neonatal seizures and put on medication. She had been seizure free for 7 months and fully off all meds after 5 months (so 3 months off meds) she then had a seizure when we put xmas lights up :-(
She has only had one episode (although we haven't had lights on since) but she was down with tree lights all day (other than nap times) and had the seizure when I took her up for her bath.
She is going to have another eeg with light stimulation but my question is do some sufferer have to have prolongep exposure to a cause before having a seizure and others can have co instant seizure?
Thank you for any advice I am currently back to being very worried as thought she had grown out of the seizures
Dear Kate,
Sorry to hear about your worries over your daughter. Photosensitive epilepsy is when someone’s seizures are triggered by lights flashing at a certain frequency. Normally if this is the way your seizures are triggered, the seizure would happen very quickly after the trigger. By this I mean seconds, or a minute or two at most. So the seizures could have been coincidental.
Hopefully the EEG will show more clearly if your daughter has photosensitive epilepsy.
It is no surprise as a mum that you are worried. If it would help to link up with other parents and carers of people with epilepsy, you may be interested in our online community,forum4e. Hope this helps.
Cherry
Advice and Information Team
Hi, i am a 45 years old woman who never had any epilepsy crisis, but today aften seing flashing lights of an emergency vehicle I felt really strange, couldnt see propoerly with aura, felt dizzy and like absent. I wonder if it is some kind of epilepsy. When I was a teenager I suffered from migraines with aura.
hi, my 14 year daughter has been diagnosed with photosensitivity epilepsy. is it safe for her to go to the cinema?
Hi Tammy
Generally going to the cinema isn’t a risk . However, some films do have flashing or flickering lights, which could trigger a seizure in people with photosensitive epilepsy.
The British Board of Film Classification (BBFC) say that the film makers and those who distribute them should identify films that may contain flashing lights. They should then make sure that warnings are given to viewers about this. However, there is no guarantee that this will always happen. So, before your daughter goes to see a particular film she could make some enquiries about it, with the BBFC.
I hope this helps.
Rosanna
Advice and Information Team
i have a question the doctors say i have photosynthesis epilepsy but they said EEG doesn't show any thing wrong but every time there are flashing lights i am said to have a tonic clonic episode but i also shake like im very cold and the nurse at my school says its just anxiety im kinda confused what is wrong ?
Hi Kristen. This is a bit tricky to give a short answer to. Photosensitive epilepsy is quite specific. And it may be you’re anxious about seizures, which would be understandable. I’m not surprised you’re confused either. If you wanted to ring us on the Epilepsy Freephone helpline 0808 800 5050, we could talk about it a bit more.
Cherry
Advice and Information Team