- As many as 70 million people have consistent sleeping issues.
- Not getting enough sleep each night can raise a person’s risk for several health concerns, including cognitive decline and dementia.
- For the first time a new study describes the synchronized oscillations during sleep that power the brain’s glymphatic system to help remove ‘waste’ associated with neurodegenerative diseases, via a mouse model.
- Researchers also found that a commonly prescribed sleep aid might suppress those oscillations, disrupting the brain’s waste removal during sleep.
- Looking at all the possible factors that might contribute to potential cognitive decline risk is important, particularly as new research estimates that dementia risk the risk after the age of 55 among Americans has now more than doubled.
Although doctors recommend that adults over the age of 18 get
Data from 2022 suggest that, in the United States alone,
Past studies report that not getting enough sleep each night can increase a person’s risk for several health concerns, including brain-related conditions, such as
“Sleep allows the brain to go offline, shut down processing of the external world and focus on maintenance tasks, such as immune surveillance and removal of waste,” Natalie Hauglund, PhD, a postdoctoral fellow at the Universities of Copenhagen in Denmark, and Oxford in the United Kingdom, explained to Medical News Today. “The lack of sleep is associated with cognitive impairment and disease development.”
But could some sleep aids also contribute to poorer brain health as we age? It is now more important than ever to study all the possible factors that might contribute to cognitive decline, particularly seeing that a new study published in
Hauglund is the first author of another study, which appears in the journal
The study also reports that the commonly prescribed sleep aid
For this study, researchers used various technologies to record brain activity while mice were both awake and asleep.
Scientists observed that slow synchronized oscillations of the neurotransmitter norepinephrine, along with cerebral blood and
“Our brain is unique in that it does not have lymphatic vessels, which removes waste products such as dead cells and bacteria from the rest of our body,” Maiken Nedergaard, MD, PhD, professor at the Universities of Rochester and Copenhagen and lead author of this study told MNT.
“Instead, the brain uses cerebrospinal fluid, a brain fluid that is produced inside the brain, to flush the brain tissue and wash away unwanted molecules,” she explained.
“The cleaning system of the brain is called the glymphatic system. Importantly, the glymphatic system is only on during the deep part of sleep called non-REM sleep. This is because of a neuromodulator called norepinephrine, which during non-REM sleep is released in slow cycles roughly every 50 seconds.”
– Maiken Nedergaard, MD, PhD
“Norepinephrine binds to the muscle cells of the arteries, which makes them constrict,” Nedergaard told us. “Therefore, the slow oscillation in norepinephrine concentration drives a slow fluctuation in the diameter of the arteries and in the blood volume in the brain.”
”This dynamic change in blood volume works like a pump to transport cerebrospinal fluid along the arteries towards the brain and through the brain tissue. Thus, norepinephrine coordinates the synchronized constriction and dilation of the blood vessels which drives the glymphatic system,” she detailed.
Researchers also examined if sleep aids might replicate the natural oscillations needed for glymphatic function. They focused their research on the sedative zolpidem.
They discovered that zolpidem appeared to halt norepinephrine oscillations, interrupting the glymphatic system’s waste removal in the brain during sleep.
“Sleep aids may provide a short-cut to sleep, but our study shows that the sleep you get with sleep medication may lack the beneficial effects of natural, restorative sleep,” Hauglund said. “Our findings underscore that sleep aids should only be used for short periods of time and as a last resort.”
Nedergaard explained that:
“Sleep is crucial as it gives the brain time to perform homeostatic housekeeping tasks such as waste removal. On the contrary, sleep aids block the neuromodulators that drive the waste removal system and prevent the brain [from] properly preparing for a new day.”
MNT also spoke with Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA, about this study.
According to Segil, who was not involved in the recent research, “it is extremely unlikely the benefits of increased sleep which occurs when patients use a sleep aid like zolpidem are outweighed by any claimed potential adverse effect of this medication decreasing REM sleep, which then in turn decreases brain neurotransmitter levels, [which] then in turn decreases brain protein levels,”
“There are too many ‘in turn’ claims to cause me any concern [that] there is any clinical significance to the research,“ he told us. “Clinical neurologists like me are not concerned [that] using zolpidem appropriately in elderly patients who can’t sleep will cause dementia.”
Furthermore, he pointed out: “In the year 2025, there remains no accepted response on why we sleep. Different researchers make different claims and sometimes these are the same and sometimes they are different. We know healthy sleep makes us healthy and poor sleep makes us unhealthy.”
“For clinical neurologists like me, it is challenging to agree that a sleeping medication will cause dementia, and I would reassure my patients the benefits or a good night sleep outweigh any claimed potential risk these can cause memory loss as you age or dementia,” Segil added.
Finally, MNT spoke with Peter G. Polos, MD, PhD, FCCP, FAASM, an assistant professor of sleep medicine at the Hackensack Meridian Neuroscience Institute at JFK University Medical Center in New Jersey, about this research.
Polos, who was not involved in the study, commented that he found the results intriguing.
“There is no doubt that the interaction between the glymphatic system and various transmitters and waste products in the brain can work in synchrony,” he said.
“This study suggests that alterations in this tight balance have potential cellular and perhaps clinical consequences. While fascinating, we must remind ourselves that this is an animal study and, as is often the case, extrapolation of animal data to humans must be done cautiously. Nonetheless, it does give clinicians a phenomenon that is deserving of some discussion.”
– Peter G. Polos, MD, PhD, FCCP, FAASM
“If more work were to be done in this area, we certainly would like to see if studies could assess the impact of sleep aids on human glymphatic flow,” Polos continued. “This of course would require noninvasive techniques and perhaps some advanced imaging. Such information, even if in small numbers, would be of benefit.”
“The interaction between the brain, quality sleep, and overall health cannot be understated,” he added. “The rhythmic nature of sleep and the regular cycling of sleep stages have been well studied, We have learned much about the effects of alterations in the brain and their impact on sleep, We do have much more to learn and so we, as sleep physicians, fully support continued research in the relationship between the brain, sleep, and overall health.”
