Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 20, 2025 2 weeks, 4 days, 11 hours, 24 minutes ago
Thailand Medical News: A new study by Chinese researchers has revealed a shocking link between long COVID-related sleep problems and damage to the brain’s natural waste removal system, called the glymphatic system. This discovery helps explain why many people who recover from COVID-19 continue to suffer from serious sleep disturbances long after the infection is gone.
COVID-19 Sleep Problems May Be Caused by Damaged Brain Waste System
The study was carried out by scientists from The First Affiliated Hospital of Hunan Normal University (also known as Hunan Provincial People’s Hospital) in Changsha, Hunan Province, and the Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, in Hangzhou. Using an advanced brain imaging technique called Diffusion Tensor Imaging (DTI) with a method known as Analysis along the Perivascular Space (DTI-ALPS), the research team closely monitored changes in the glymphatic system in individuals with post-COVID sleep disorders. This
Thailand Medical News report takes a closer look at their groundbreaking findings.
What Is the Glymphatic System and Why Does It Matter
The glymphatic system is a recently discovered network in the brain responsible for clearing away waste products and harmful proteins while we sleep. It works by allowing cerebrospinal fluid to flow along the spaces around blood vessels, flushing out toxins from brain tissues. Think of it as the brain’s plumbing system. If this system becomes clogged or weakened, waste builds up, which may lead to brain fog, memory issues, and poor sleep.
Earlier studies have shown that poor glymphatic function is linked to diseases like Alzheimer’s, Parkinson’s, and PTSD. This new research is among the first to show that COVID-19 may also impair glymphatic flow—especially in people who suffer from post-infection sleep problems.
How the Study Was Conducted
Between January and March 2023, the researchers recruited 98 individuals who had recovered from COVID-19. Among them, 59 people developed new sleep problems after recovering (the COVID_SD group), while 39 others did not (COVID_NSD group). Participants were carefully screened to ensure no other health issues affected their sleep, and no one had taken sleep medications during the study.
All participants underwent brain scans using DTI-ALPS and filled out sleep quality surveys based on the Pittsburgh Sleep Quality Index (PSQI), where a higher score means worse sleep. They were evaluated initially and again two months later to observe any changes in their brain function and sleep quality.
The Surprising Results
At the start of the study, people with post-COVID sleep problems had significantly lower glymphatic activity than those without sleep problems. This was shown by reduced ALPS index scores on both sides of the brain. Importantly, the researchers found a clear and strong negative correlation between glymphatic function and sleep quality: the worse the sleep, the poorer the brain&
amp;rsquo;s waste-clearing performance.
Specifically, the left-side ALPS index in the sleep disorder group was 1.23 compared to 1.29 in the non-disorder group, while the right-side index was 1.29 versus 1.33. These differences were statistically significant.
After two months, the same group of participants was scanned again. Encouragingly, those with previous sleep issues showed some improvement in both their sleep scores and ALPS indices, indicating partial recovery of glymphatic function. However, their scores still remained lower than those of people who had no sleep problems to begin with.
Why COVID Might Be Harming the Brain’s Waste System
SARS-CoV-2, the virus behind COVID-19, is not traditionally known as a brain-invading virus. However, mounting evidence shows it can reach brain tissues and cause inflammation. Scientists believe this may happen through the glymphatic system itself—essentially allowing the virus to travel deeper into the brain by hijacking the very system meant to clean it.
By doing so, the virus may damage or disrupt this system, leading to the buildup of toxic materials and interfering with the brain’s natural sleep-wake cycles. This could explain the high number of long COVID patients complaining of insomnia, restlessness, and daytime sleepiness months after their initial infection.
The Link Between Sleep Quality and Brain Recovery
The study also found that two specific aspects of sleep—sleep quality and how long it takes to fall asleep (sleep latency)—were most strongly tied to changes in the glymphatic system. People who rated their sleep as poor or who took longer to fall asleep had lower ALPS scores.
Even more striking was the finding that improvements in glymphatic function were closely tied to improvements in sleep scores. As brain clearance improved, people reported better sleep. This suggests a direct two-way relationship: fixing the glymphatic system may help sleep, and sleeping better may boost brain cleanup.
Brain Hemispheres Recover Differently
One of the more curious findings was that the left side of the brain seemed more affected by glymphatic dysfunction than the right side. Over time, the right hemisphere showed a faster recovery. Researchers suspect that this difference might be linked to the fact that all participants were right-handed—hand dominance has been linked to how the brain is structured and how blood flows differently between hemispheres.
This pattern of uneven damage and recovery might help explain the diverse range of neurological symptoms seen in long COVID patients.
Study Limitations and Future Directions
Although this was a well-controlled and carefully conducted study, it had some limitations. The sample size was relatively small and limited to one geographic area in China. Also, while the DTI-ALPS technique is a reliable indicator of glymphatic activity, it only measures activity during wakefulness. Since glymphatic clearance is most active during sleep, future studies may need to explore this with other methods, including sleep-state brain scans or biomarkers of inflammation.
More research is needed to confirm whether this glymphatic dysfunction is unique to COVID-related sleep problems or whether it also appears in other types of sleep disorders.
Conclusions
This study provides the clearest evidence so far that sleep problems following COVID-19 are not just psychological or emotional in nature—they may stem from actual damage to a vital system in the brain that flushes out waste. Using an advanced but non-invasive brain imaging technique, researchers showed that this glymphatic dysfunction is significantly worse in those suffering from post-COVID sleep disorders. Importantly, improvements in sleep were accompanied by improvements in this brain function, suggesting that recovery is possible. These findings offer hope and also open new doors for treating long COVID symptoms through brain-targeted therapies that support glymphatic health.
The study findings were published in the peer reviewed journal: Nature and Science of Sleep
https://www.tandfonline.com/doi/full/10.2147/NSS.S522745
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Read Also:
https://www.thailandmedical.news/news/study-reveals-alarming-connection-between-disruption-of-brain-waste-clearance-and-long-covid-symptoms
https://www.thailandmedical.news/news/covid-19-causes-glymphatic-drainage-dysfunction-and-bbb-disruption-that-contributes-to-neuroaxonal-injury
https://www.thailandmedical.news/news/breaking-covid-19-news-study-alarmingly-finds-that-recovered-individuals-who-only-had-mild-covid-19-exhibit-glymphatic-system-dysfunction
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