Not getting enough sleep each night raises significant concerns for one’s health, including an increased risk of cognitive decline and dementia. Recent studies indicate that dementia risk after the age of 55 among Americans has more than doubled when compared to previous estimates. With doctors recommending at least 7 hours of quality sleep per night for adults over 18, this news highlights an urgent call to address sleep-related issues. Many adults face consistent challenges like insomnia and sleep apnea, affecting their cognitive health in the long run.
Sleep aids, often used to combat these sleep issues, block neuromodulators critical for the brain’s waste removal system. Norepinephrine, a key neuromodulator, binds to muscle cells in artery walls, promoting constriction in slow cycles during non-REM sleep. The glymphatic system, crucial for removing waste linked to neurodegenerative diseases, operates during sleep through synchronized oscillations.
"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," explained Natalie Hauglund, PhD.
A study published in the journal Cell using a mouse model elaborates on these oscillations that power the glymphatic system. This system’s importance in removing waste is crucial for preventing cognitive impairments and disease development.
"The lack of sleep is associated with cognitive impairment and disease development," added Hauglund.
Globally, an astounding 70 million people suffer from consistent sleep issues. Despite extensive research, there remains no universally accepted explanation as to why sleep is essential. Nonetheless, its significance in preparing the brain for a new day is undeniable.
"In the year 2025, there remains no accepted response on why we sleep," noted Segil. "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."
Peter G. Polos, MD, PhD, FCCP, FAASM commented on the study’s implications.
"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."
Polos also emphasized the importance of further research on the impact of sleep aids on human glymphatic flow.
"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."
The interaction between quality sleep and overall health remains a critical focus for future studies.
"The interaction between the brain, quality sleep, and overall health cannot be understated," Polos stated.
Despite concerns about sleep aids affecting glymphatic function, Segil remained skeptical about their adverse effects.
"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."
Segil further argued that there are too many intermediate claims to warrant concern about medications like zolpidem leading to clinical significance.
“There are too many ‘in turn’ claims to cause me any concern [that] there is any clinical significance to the research," he asserted.
The unique nature of the human brain without lymphatic vessels adds complexity to this issue.
"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," explained Maiken Nedergaard, MD, PhD.
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