Not all sleep is equal when it comes to cleaning the brain

28 Mar Not all sleep is equal when it comes to cleaning the brain

New research shows how the depth of sleep can impact our brain’s ability to efficiently wash away waste and toxic proteins. Because sleep often becomes increasingly lighter and more disrupted as we become older, the study reinforces and potentially explains the links between ageing, sleep deprivation, and heightened risk for Alzheimer’s disease.

The study, which appears in the journal¬†Science Advances, indicates that the slow and steady brain and cardiopulmonary activity associated with deep non-REM sleep are optimal for the function of the glymphatic system, the brain’s unique process of removing waste. The findings may also explain why some forms of anaesthesia can lead to cognitive impairment in older adults.

The study raises several important clinical questions. It further bolsters the link between sleep, ageing, and Alzheimer’s disease. It is known that as we age it becomes more difficult to consistently achieve deep non-REM sleep, and the study reinforces the importance of deep sleep to the proper function of the glymphatic system. The study also demonstrates that the glymphatic system can be manipulated by enhancing sleep, a finding that may point to potential clinical approaches, such as sleep therapy or other methods to boost the quality of sleep, for at-risk populations.

Furthermore, because several of the compounds used in the study were analogous to anaesthetics used in clinical settings, the study also sheds light on the cognitive difficulties that older patients often experience after surgery and suggests classes of drugs that could be used to avoid this phenomenon. Mice in the study that were exposed to anaesthetics that did not induce slow brain activity saw diminished glymphatic activity.


University of Rochester Medical Center. “Not all sleep is equal when it comes to cleaning the brain.” ScienceDaily. ScienceDaily, 27 February 2019.