Good sleep can help your body feel refreshed, but it can also help your brain health. A new study from researchers at the University of Hong Kong found poor sleep among their older study participants prevented their brains from fully utilizing the built-in waste removal system.

That means a bad night's sleep does not allow your brain to take out the trash.

Previous studies have linked poor sleep with diminished brain functioning so professor Tatia M.C. Lee and her team sough to understand more about the causes. They focused on the fluid transport pathway that plays a vital role in clearing waste from the brain.

The researchers found a direct link between poor sleep and diminished efficiency in the glial-lymphatic (glymphatic) system. That system is a major determinant of brain health, especially in aging populations.

Lee and her team said dysfunction in the glymphatic system leads to the accumulation of toxic proteins, which are linked to neurological disorders like Alzheimer's disease, Parkinson's disease and epilepsy.

"Sleep quality, brain activities, and glymphatic functioning are related," Lee said. "Understanding how sleep quality influences the glymphatic system and human brain networks offers valuable insight into the neurophysiological mechanisms underpinning age-related memory change."

Lee and fellow scientists studied 72 older adults by using functional MRI scans and sleep recordings. They found that when a study participant had poor sleep quality it adversely affected brain function. That was demonstrated by the deactivation of the restorative glymphatic system.

"The results clearly reveal the effect of sleep on the human brain's network through the glymphatic system, which in turn affects memory performance in older adults," Lee said. "Therefore, maintaining efficient glymphatic functioning seems crucial for promoting healthy aging."

The findings underscore the importance of proper sleep. The quality of sleep directly affected the cognitive health of the study participants by altering neural relationships.

"Impaired memory is a common complaint among older adults with poor sleep quality," Lee noted. "Our results provide a novel perspective on the interplay between sleep, the glymphatic system and multimodal brain networks."

Click here to read more in the journal Molecular Psychiatry.