Scientists Say: Glymphatic System

The glymphatic system takes out brain cells’ trash

a girl lies with her eyes closed on a bed under covers

The brain’s garbage disposal system, or glymphatic system, appears to be most active during sleep.

Yasser Chalid/Getty Images

Glymphatic system (noun, “Glim-FAT-ick SIS-tem”)

The glymphatic system is thought to be the brain’s waste-disposal system, flushing out the brain’s trash. During waking hours, brain cells chuck out bits of protein and other waste. This litter builds up between cells. During sleep, the glymphatic system bathes the brain in cleansing fluids. Those fluids flood the spaces between cells and wash away chemical junk. This trash is carried off to the liver, which gets rid of the waste.

Scientists identified this brain-cleaning system in rodents about a decade ago. But observations of brain fluids in people suggest it washes chemical garbage out of human brains, too. The name for the system comes from the words “lymphatic” and “glial.” The lymphatic system is the waste disposal system for the rest of the body. It washes fluid through other tissues to clear out chemical trash. Glial cells are those in the brain that control the glymphatic system. These cells are tasked with supporting and nourishing the brain’s nerve cells, or neurons.

The glymphatic system may help explain why all animals need sleep to survive. Without sleep, this brain cleaning service may not be able to do its work.

Problems with the glymphatic system may also lead to some brain disorders. For instance, Alzheimer’s disease is linked to the buildup of protein bits called amyloid-beta in the brain. That’s one of the pieces of chemical trash the glymphatic system is responsible for removing. Likewise, Parkinson’s disease is linked to harmful proteins piling up in the brain. Learning more about the glymphatic system and its connections to diseases may lead to new treatments.

In a sentence

The spaces between brain cells widen to let the glymphatic system flush fluids through these channels during sleep.

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Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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