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Seizures and hot summers

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Nicola Swanborough

Seizures and hot summers

Thank you to everyone who took part in our recent surveys looking at the impact of excessively high temperatures on seizures. These have provided us with some invaluable insight into the link between the two and will help to influence our work as we experience increasingly hot summers.

A survey carried out by the Epilepsy Society has shown that 62 per cent of people with uncontrolled seizures experience an increase in their seizure activity during unusually hot weather.

More than 1,000 people responded to our survey, including 969 people whose epilepsy does not respond to current treatments. A total of 598 of this group said that they experienced a change in their seizure activity during very hot weather. This included an increase in frequency, severity or a ‘breakthrough’ seizure even when they considered their epilepsy to be generally well controlled. 

The charity conducted its survey following the week of 21-27 June 2020, when temperatures soared above 30 degrees Celsius. 

Researchers at the charity are keen to understand more about how hot weather affects people with epilepsy and the impact that climate change might have in the future.


“Cannot sleep due to high temperatures, therefore as well as the high heat affecting my seizures ,also have to deal with sleep deprivation seizures” - respondee

Anecdotal evidence has already suggested an increase in seizure activity for children with Dravet syndrome, a severe childhood epilepsy. Dravet Syndrome UK, has shown that the unusually high temperatures of summer 2018 resulted in children with this rare condition, caused by a mutation in the SCN1A gene, experiencing more seizures and greater lethargy. 

One girl with Dravet syndrome in Australia died after being out in temperatures of 40 degrees C. Temperature changes are known to affect some genes and proteins.

But the Epilepsy Society’s survey is the first time that data has shown a direct link between excessively hot weather and seizures in a large group of people with epilepsy in the UK. 


“More extreme heat will make my seizures more frequent but also the impact of the seizures worse. And the recovery from the seizures longer” - respondee

Significantly, 40 per cent of respondees expressed concern that climate change would affect their epilepsy or the epilepsy of the person they cared for. And 75 per cent said they would like to see more research into the impact of climate change on the condition and what could be done to address it.

Taking action

Professor Sanjay Sisodiya, Director of Genomics at the Epilepsy Society said that not only did the survey capture important data about the link between temperature and seizures, but it also highlighted a growing concern among people with epilepsy that unless we take measures now to control global warming, their own health could be adversely affected.

“If the hot summers that we are experiencing now are contributing to worsening control of some people’s seizures, then we, as their doctors, need to understand that connection and take appropriate action to reduce risk by helping to tackle climate change or to mitigate its effects,” he said.


High heat always causes my son to have breakthrough seizures” - respondee

According to research, climate change directly related to human causes such as carbon emissions make the likelihood of extreme temperatures a near certainty. Scientists warn that human influence is increasing the risk of UK summer temperatures regularly exceeding 35 degrees C.

With current emission rates, UK temperatures are likely to hit 40 degrees C every 100-350 years. Under the worst-case scenario, without mitigating greenhouse emissions, these excessive temperatures could occur every 3.5 years by 2100 (


Prof Sisodiya has formed an international consortium – Epilepsy Climate Change (EpiCC) – specifically to address the issue.

Earlier this year, EpiCC carried out a small, preliminary study to help them begin to understand more about people’s perceptions of climate change and how it is affecting their epilepsy.

46% of people responding said that the frequency of their seizures changed during the hot summer of 2018, while 37% said their severity altered. During the hot summer of 2019, 50 per cent reported a change in both frequency and severity. 

Over 90% said they are concerned about climate change with almost half (46%) worrying that climate change will affect their epilepsy. Almost 40% said that thinking about climate change affects their mental well being, with 86% saying it causes them anxiety and 20% depression.

The majority of respondees (87%) believe that it is the responsibility of everyone, rather than just governments, to tackle climate change. And 80% have already taken action to try to reduce their own impact on the environment. This includes recycling domestic waste, using energy efficient light bulbs, avoiding single use plastics, and turning off lights.

87% said they would consider having a remote consultation with their healthcare professional, at least some of the time, if it helped to reduce carbon emissions. And almost one in three (31%) said they felt doctors should find alternative ways to network and share research, rather than flying to international conferences which carry a heavy carbon footprint.

Prof Sisodiya and EpiCC are planning to share and generate more scientific discussion around epilepsy and climate change through a series of webinars at the end of the year. This will also provide an opportunity for people affected by epilepsy to take part in a workshop about the impact of global warming on seizures.

We will bring you further updates nearer the time.

Our longer survey

If you are concerned about the impact that climate change might have on seizures, you might like to take part in our longer survey Epilepsy and Climate Change. This will help us to understand more about the link between rising temperatures and seizure activity. It will also help us to address global warming in the most appropriate ways.

Thank you.


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