Sleep may encode epileptic seizures in the brain by reusing the processes used to consolidate memories, potentially making seizures more difficult to treat or prevent, new research suggests. But the new study also suggests a possible way to counteract the effect: using electrical stimulation to prevent the brain from “memorizing” the seizure, the researchers say.
“It opens up a whole new area of therapeutic options tailored to each patient,” said the study’s co-author Vaclav Kremena neuroscientist at the Mayo Clinic. He added that electrical stimulation could be tailored to each individual’s unique seizure profile.
Sleep and seizures
People often struggling to store memories after epileptic seizuresand research on rats suggests that this occurs because the brain’s memory storage system solidifies neuronal connections that trigger seizures rather than locking in memories. However, the connection between epilepsy, memory and sleep has not been adequately assessed in humans because most of these studies involve measuring brain activity for only a few days, and the research usually takes place in clinics, which are not conducive to a good night’s sleep.
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“Hospital stays can alter sleep and seizure patterns due to medication adjustments, stress, noise and disrupted routines,” Dr. Erin Conrada neuroscientist at the University of Pennsylvania who was not involved in the work told LiveScience in an email.
In the new study, published March 4 in Journal of Neuroscienceelectrodes were implanted for months or years in participants who slept at home, allowing the researchers to collect data over a long period of time without disturbing their sleep. “It gives a more realistic picture of how sleep changes after seizures in everyday conditions,” Conrad said.
The team analyzed two groups of participants with drug-resistant epilepsy who participated in between 2010 and 2011 at the University of Melbourne in Australia or between 2019 and 2023 at the Mayo Clinic in Minnesota. One group was implanted with deep brain stimulation devices that can detect and reduce seizure activity, while the other received a seizure counseling research system that records brain signals but does not attempt to interrupt seizures. The study was small, with a total of 11 participants, so the findings may not be generalizable to all epilepsy patients, Kremen told LiveScience. Nevertheless, the work provides clues as to how altered brain patterns during sleep may underlie the link between epilepsy and memory.
The team found that people slept about 24 minutes longer on nights after epileptic seizures, but not all stages of sleep were prolonged.
If the theory holds true, this type of adaptive, closed-loop system could become a new way to customize treatment
Dr. Erin Conrad, neuroscientist at the University of Pennsylvania
Rapid eye movement (REM) sleep, which is important for emotion processing and dreamingshortened by about 12 minutes on nights after an epileptic seizure compared to nights between seizures. Dr. Laurent Sheybania neuroscientist at the University of Geneva who was not involved in the work told LiveScience in an email that “12 minutes may actually seem low, but keep in mind that the total duration of REM sleep is not very long either” — typically about 1 hour and 40 minutes — so the decrease makes sense.
What replaces the missing minutes of REM sleep also matters, Conrad said. The team found an increase in the length and intensity of the deepest stage of sleep, called the slow-wave stage, which is key to store memories. One hypothesis is that the brain uses memory-forming pathways to “remember” how to form seizures in the future, but the observations from this study alone cannot show that this is the case.
Predicting seizures using sleep patterns
In future work, the team needs to determine whether prolonging the memory-forming sleep stage actually enhances epileptic seizures by “memorizing” the seizure pathways.
“Using brain devices that adjust stimulation based on both seizure and sleep patterns is an exciting possibility,” Conrad said. Such devices use electrodes to record brain activity and deliver an electrical impulse to stop a seizure as soon as it is detected. They use a closed-loop feedback system to improve detection over time as the system recognizes a specific person’s seizure patterns.
“This type of approach can help test the study’s main idea by seeing whether changing sleep-related brain activity after a seizure reduces the chance of future seizures,” Conrad added. “If the theory holds up, this type of adaptive, closed-loop system could become a new way to customize treatment.”
Kremen said the findings suggest that electrical brain stimulation that interrupts this seizure memory formation may be an additional future treatment along with medication for patients with drug-resistant epilepsy. “We’re really invested in trying to find therapies for very sick people with epilepsy who have no hope with standard drug therapies,” he said.
This article is for informational purposes only and is not intended to provide medical advice.
