Sleep May ‘Encode’ Seizures in Brain, But Electrical Stimulation Offers Hope

For people living with epilepsy, sleep following a seizure may inadvertently reinforce the brain activity that triggers those seizures, making them harder to control. A new study suggests that sleep can essentially “encode” seizures in the brain by reactivating the processes used to solidify memories – a finding that could complicate treatment, but likewise open new avenues for intervention. Researchers are exploring the potential of using electrical stimulation to disrupt this process, preventing the brain from “saving” the seizure event.

“This opens up a whole new world of therapeutic options tailored to each patient,” says Dr. Vatslav Kremen, a neurologist at the Mayo Clinic and co-author of the study. He explains that electrical stimulation could be personalized to address each individual’s unique seizure patterns.

The Interplay of Sleep and Seizures

People often struggle with memory consolidation after experiencing a seizure, and research in animal models indicates this may occur because the brain’s memory storage system strengthens the neural connections that lead to seizures, rather than solidifying memories. However, the relationship between epilepsy, memory, and sleep hasn’t been thoroughly investigated in humans, largely because most studies have only measured brain activity for short periods, typically within clinical settings that don’t reflect normal sleep patterns.

The new study, published March 4 in Neurology, overcomes this limitation by utilizing implanted electrodes to monitor participants’ brain activity while they slept at home over extended periods. This allowed researchers to collect data without the disruptions of a hospital environment, providing a more realistic picture of how sleep and seizures interact in daily life. As Dr. Irene Conrad, a neurologist at the University of Pennsylvania who was not involved in the study, explained to Live Science, “This gives a more realistic picture of how sleep and seizures change in everyday life conditions.”

The research team analyzed data from two groups of participants with drug-resistant epilepsy, recruited between 2010 and 2011 at the University of Melbourne in Australia, and between 2019 and 2023 at the Mayo Clinic in Minnesota. One group had deep brain stimulation devices implanted, capable of detecting and reducing seizure activity, while the other group received a recording system to monitor brain signals without intervention. The study was relatively small, involving 11 participants, so the findings may not be generalizable to all people with epilepsy. However, the research offers valuable insights into how changes in brain patterns during sleep could underpin the connection between epilepsy and memory.

The team found that participants slept approximately 24 minutes less on nights following a seizure. However, not all stages of sleep were affected equally.

Rapid eye movement (REM) sleep, crucial for emotional processing and dreaming, was reduced by about 12 minutes on nights following a seizure compared to nights without seizures. Dr. Laurent Schibani, a neurologist at the University of Geneva who was not involved in the work, noted to Live Science that while 12 minutes may seem small, it’s significant considering the typical REM sleep duration is around 1 hour and 40 minutes.

What replaces the lost REM sleep is also important. The researchers observed an increase in the duration and intensity of slow-wave sleep, a deeper stage of sleep essential for memory consolidation. One hypothesis is that the brain utilizes memory formation pathways to “remember” how to generate seizures in the future, but the data from this study alone cannot confirm this.

Forecasting Seizures Using Sleep Patterns

Future research will demand to determine whether prolonging memory consolidation during sleep actually strengthens seizures by “saving” seizure pathways. Dr. Conrad suggests that devices capable of adjusting stimulation based on seizure activity and sleep patterns hold considerable promise. These devices apply electrodes to record brain activity and deliver electrical pulses to stop a seizure once detected, employing a closed-loop feedback system to refine detection over time as the system learns an individual’s seizure patterns.

“This type of approach could assist test the central idea of the study by determining whether changing brain activity associated with sleep after a seizure reduces the chance of future seizures,” Conrad explained. “If the theory holds true, these types of adaptive closed-loop systems could become a new way to personalize treatment.”

Dr. Kremen emphasizes that the findings suggest that electrical brain stimulation that interrupts the formation of seizure memories could be a future adjunct therapy alongside medication for patients with drug-resistant epilepsy. “We are really investing in trying to find treatments for very sick people with epilepsy who have no hope with usual drug treatments.”

The development of responsive neurostimulation (RNS) systems, approved by the FDA in 2013, and deep brain stimulation for epilepsy, approved in 2018, represent significant advancements in treating epilepsy. The Epilepsy Foundation of Minnesota details how these systems offer alternatives to resective epilepsy surgery for patients whose seizures cannot be controlled with medication. These systems differ in their mechanisms, stimulation sites, and operation – RNS® is believed to terminate seizure discharge by directly stimulating the area where seizures originate, while deep brain stimulation targets the thalamus.

Understanding the complex relationship between sleep, seizures, and memory is crucial for improving the lives of those living with epilepsy. While more research is needed, these findings offer a glimmer of hope for more personalized and effective treatments in the future. For individuals concerned about epilepsy and sleep, consulting with a qualified clinician is essential for developing a tailored management plan. You can find more information about epilepsy and available treatments from organizations like the Mayo Clinic and the Centers for Disease Control and Prevention.