Myelin Damage Triggers Abnormal Brain Rhythms During Sleep

Summary: Researchers discovered that when the protective, insulating myelin coating around nerve fibers breaks down, it destabilizes underlying neural networks. Utilizing continuous, multi-night electroencephalogram (EEG) recordings, the team proved that this structural decay triggers abnormal, epilepsy-like electrical spikes and severely slows down critical memory-replay oscillations, occurring exclusively while the subject is asleep.

Key Facts

The Sleep-Locked Spike Phenomenon: EEG recordings revealed distinct, abnormal electrical spikes in brain activity that look remarkably similar to those observed in clinical epilepsy or advanced Alzheimer’s patients. Crucially, these pathognomonic spikes emerged exclusively when the subjects were asleep.
Coupling With Sleep Spindles: These abnormal spikes do not occur randomly; they are tightly locked to Stage 2 non-rapid eye movement (NREM) sleep rhythms. Specifically, they ride on the back of sleep spindles, the quick bursts of oscillatory brain activity essential for sensory gating and early memory processing.
Slowing the REM Engine: In addition to NREM disruptions, demyelination caused a profound structural slowing of electrical rhythms (oscillations) that are exclusively observed during rapid eye movement (REM) sleep.
The Dream-State Failure: REM sleep is responsible for intense dreaming and the mechanical replay of daytime experiences. Dr. Dubey notes that when myelin degenerates, the rhythmic electrical oscillations required to coordinate long-distance communication between dreaming neurons become severely sluggish and fragmented.
A Non-Invasive Myelin Tracker: Because these abnormal electrical signatures track perfectly with myelin decay, overnight sleep recordings could serve as an incredibly sensitive, non-invasive biomarker to detect early changes in brain circuit myelination long before clinical physical symptoms emerge.
A Midnight Therapeutic Window: Currently, no approved drugs can actively repair stripped myelin. Unlocking this biological link raises an exciting new therapeutic possibility: engineering non-invasive, targeted sleep-signal treatments designed to stimulate and repair myelin sheaths while the patient rests.

Source: FENS

Scientists have discovered how damage to the myelin sheath – the insulating layer around nerve fibres – affects brain activity during sleep.

In research presented on Friday at the Federation of European Neuroscience Societies (FENS) Forum 2026, Dr Mohit Dubey 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 (AD). These spikes occurred only when the mice were asleep. The findings may have implications for patients with multiple sclerosis (MS), AD and other neurodegenerative diseases.

“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, who is a ZonMw Memorable Dementia Fellow at the Netherlands Institute for Neuroscience in Amsterdam, The Netherlands.

“The myelin sheath helps electrical signals travel efficiently through brain circuits. In many neurodegenerative diseases myelin is damaged, which 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.”

Dr Dubey and colleagues looked at EEG recordings taken over multiple nights over several weeks in mouse models with damaged myelin and AD, and compared them with EEG data from sleeping patients with MS.

They found that the abnormal electrical spikes in brain activity seen in the sleeping mice were tightly linked to sleep rhythms, including the bursts of brain activity that occur during the second stage of non-rapid eye movement (REM) sleep (known as sleep spindles). Furthermore, they discovered slowing of electrical rhythms that are exclusively observed during 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.

“This opens new research directions exploring how sleep rhythms depend upon the myelination status of the brain circuits. Sleep recordings may provide a non-invasive way to detect early changes in brain circuit myelination in neurological disease. This could eventually help clinicians monitor disease progression, and we want to investigate whether sleep recordings could be used as biomarkers to detect early changes in brain circuit function.

“Sleep disturbances are already known to affect quality of life in people with MS and AD. They contribute to fatigue and cognitive decline. Therefore, understanding the biological link between sleep and brain circuit dysfunction could help guide future strategies for improving sleep and brain health in these conditions.

“Sleep plays a fundamental role in maintaining healthy brain function, but it has often been overlooked in the study of neurodegenerative disease.”

Dr Dubey’s future research will focus on understanding the cellular and molecular mechanism linking myelin degeneration, sleep rhythms and abnormal electrical activity in the brain.

As yet, there are no treatments that can repair damaged myelin, although there are some drugs that aim to slow the immune system’s attack on the myelin sheath in MS. Understanding the biological basis for how myelin damage affects sleep could help researchers to design non-invasive approaches that might be able to repair myelin during sleep.

A strength of the research is that it combines sleep neuroscience with the study of demyelinating brain circuits, allowing researchers to examine how brain rhythms interact with disease-related changes. A limitation is that the work is mainly in mice and further studies are needed to understand how the mechanisms translate to human disease.

Professor Christina Dalla from the National and Kapodistrian University of Athens, Greece, is chair of the FENS Forum communication committee and was not involved in the research. she said: “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.”

Key Questions Answered:

Q: Why do these dangerous, epilepsy-like brain spikes only show up when the subject is asleep?

A: When you are awake, your brain is flooded with constant sensory input and active conscious control, which keeps neural networks tightly regulated. But when you fall asleep, your brain shifts into a highly synchronized, rhythmic state driven by massive waves of electrical oscillations. Dr. Mohit Dubey’s research reveals that the insulating myelin sheath is absolutely vital to keep these delicate sleep rhythms stable. When myelin is damaged, the brain’s internal electrical lines short-circuit under the pressure of these rhythmic sleep waves, causing erratic, epileptiform spikes to flare up exclusively in the dark.

Q: What are “sleep spindles,” and how do they connect to memory loss in diseases like Alzheimer’s?

A: Sleep spindles are sudden, fast bursts of brain activity that light up on an EEG during Stage 2 deep sleep. They act like a digital bridge, helping your brain organize, sort, and transfer your daytime experiences into long-term memory storage. This study proved that myelin damage directly corrupts these spindles, latching abnormal electrical spikes onto them. When your sleep spindles are systematically disrupted night after night, your brain cannot properly execute its memory-saving routines, directly contributing to the rapid cognitive decline and forgetfulness seen in MS and Alzheimer’s.

Q: How could analyzing someone’s sleep patterns help doctors catch neurological diseases years earlier?

A: Right now, diseases like Multiple Sclerosis and Alzheimer’s are incredibly difficult to diagnose early because structural damage can hide silently inside the brain for years before a patient shows physical symptoms like walking problems or memory lapses. Because this FENS Forum study proves that sleep rhythms are deeply sensitive to the health of your myelin wiring, a simple, non-invasive overnight sleep study could act as an early-warning radar. Spotting slowed REM oscillations or locked Stage 2 spikes could allow doctors to intervene and protect a patient’s brain circuits years ahead of schedule.