The brain activity of people with epilepsy shows that their exhausted brains never really get the rest they need, setting them up for problems with thinking and attention during the day.
University of Wisconsin School of Medicine and Public Health research shows a reinforcing circuit that deprives people with epilepsy of restful sleep: Seizures exhaust the brain, but the brain regions where the seizures originate continue to send off abnormal activity during the night. As a result, the brains never get the reset that sleep normally affords.

“What we saw was that epilepsy patients had really abnormal sleep,” says lead author Dr. Melanie Boly, a neurology resident. “It’s as if they have more sleep need, and their sleep doesn’t compensate for it.”

The study looked at 15 patients, each of whom wore nets that covered their heads with 256 electrodes to create a picture of their brain activity during sleep. They slept with this net during one of the nights they spent at the UW Epilepsy Monitoring Unit.

The study was funded by Lily’s Fund, a local organization dedicated to raising money for epilepsy research at UW–Madison. Lily’s Fund has raised more than $1 million since the first Lily’s Luau in 2009. With its Grace Grants it supported the work of study authors Dr. Giulio Tononi, professor of psychiatry, and Dr. Rama Maganti, professor of neurology, to investigate using high–density electroencephalography (HD–EEG) to locate the source of seizures and to better understand how epilepsy affects sleep.

The HD–EEG study showed a sleep pattern that differed from normal sleep. In a normal brain, the night begins with deep slow–wave sleep. As the night continues, the brain becomes more rested and sleep becomes lighter, signaled by smaller slow waves. But in people with epilepsy, the slow waves were larger and did not diminish as much over the night, indicating the brain was never rested. The larger slow waves were also associated with poorer scores on intelligence and other cognition tests.

“We need sleep to recover from one day to another; it helps clear the synapses in the brain,” Boly says. “Their brains look like they never rested, which can lead to problems with learning the next day.”

Maganti, the study’s senior author, says the sleep was also interrupted by small spikes of electrical activity, described as “micro seizures,” which also interrupted the healing power of sleep.

Additionally, the study saw a correlation between the large slow waves and seizures in previous days.

“Interestingly, these big slow waves were occurring in the areas where seizures were likely to be coming from,” he says. “That was never reported before.”

The authors plan another study to see if high–density EEG sleep studies can help pinpoint areas of the brain where seizures are originating, to identify them for possible surgery or other interventions. Current methods use an invasive method of placing probes into the brain itself. Additionally, they want to investigate if treating epilepsy patients to improve their sleep also improves their cognition.

The study was published in the April edition of the journal Brain.