Sleep Helps Flush Waste From the Brain
In mice, sleep expands the space between brain cells, helping cerebrospinal fluid wash away waste, including proteins linked to Alzheimer’s disease.
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Sleep does more than give the brain a break. Research in mice found that during sleep, the space between brain cells expands substantially, allowing cerebrospinal fluid to move more freely through brain tissue and increase the clearance of metabolic waste. The process is part of what researchers call the glymphatic system, a brain waste-clearance pathway involving fluid movement around blood vessels. The 2013 study found faster removal of beta-amyloid, a protein associated with Alzheimer’s disease, in sleeping mice than in awake mice. Later research has continued to investigate how sleep, brain fluid movement, blood flow, and waste clearance interact, including evidence from human studies. However, the original mouse findings do not mean that sleeping prevents Alzheimer’s disease, and the exact relationship between sleep, glymphatic clearance, and human brain disorders is still being studied. The broader picture is that sleep appears to support important maintenance processes in the brain while the brain is less occupied with active information processing.
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