Scientists have found that damage to the myelin sheath, the insulating layer around nerve fibres, affects brain activity during sleep, according to research presented on July 9 at the Federation of European Neuroscience Societies Forum 2026.
Dr. Mohit Dubey, a ZonMw Memorable Dementia Fellow at the Netherlands Institute for Neuroscience in Amsterdam, described how electroencephalogram (EEG) recordings in mice with damaged myelin showed electrical spikes similar to those seen in patients with epilepsy or Alzheimer's disease. These spikes were observed only when the mice were asleep. The findings may have implications for patients with multiple sclerosis, Alzheimer's disease and other neurodegenerative conditions.
"Sleep disturbances are extremely common in neurological diseases such as multiple sclerosis and Alzheimer's disease, but the biological reasons for these problems remain poorly understood," said Dr. Dubey. He explained that myelin helps electrical signals travel efficiently through brain circuits and that its damage can disrupt communication between neurons. "We wanted to understand whether myelin damage could also affect how brain circuits behave during sleep. By studying this link, we hope to better understand what causes sleep disturbances in neurological disease and whether sleep-related brain signals could serve as biomarkers for diseases that are yet to show clinical symptoms, as well as showing disease progression," he said.
The researchers compared EEG data from mouse models with damaged myelin and Alzheimer's disease over several weeks with EEG data from sleeping patients with multiple sclerosis. They found abnormal electrical spikes during sleep were closely linked to specific sleep rhythms such as bursts of activity during non-REM stage two (sleep spindles), along with a slowing of rhythms exclusive to REM sleep.
"REM is a stage of sleep associated with dreaming and replay of daytime experiences. In this state the brain produces rhythmic electrical patterns called oscillations that help coordinate communication between neurons. Our findings show that these rhythms become disrupted and slower when myelin degenerates, and that the electrical spikes seen during sleep are closely linked to the stability of brain circuits affected by neurodegenerative diseases such as MS and AD," said Dr. Dubey.
Professor Christina Dalla from the National and Kapodistrian University of Athens commented on the study, "Dr. Dubey and his colleagues are to be congratulated on their work showing the effects of damaged myelin on the brains of sleeping mice, while also observing a slowing of REM sleep oscillations in patients with multiple sclerosis. This appears to be connected with disruptions in brain circuit stability and connectivity, as seen in mice with Alzheimer's disease. These observations open up interesting new avenues for further research on sleep quality and architecture as a biomarker for brain diseases and as a therapeutic target in humans."
