Along the outer walls of blood vessels, microscopic currents flow, sweeping away waste that would otherwise cause harm. This is the glymphatic system, a network of channels that helps the brain clear unwanted proteins and by-products of cellular metabolism. It may explain one of life’s most familiar pleasures: feeling refreshed after a good night’s sleep.
Yet we only learned of its existence in 2012, and ever since, researchers have been scrambling to figure out exactly how it works. Now, it seems this overlooked system may be crucial for our health – when clearance falters, it may contribute to Alzheimer’s and Parkinson’s disease, and possibly other hard-to-treat conditions, including migraine. Doctors are eager to intervene, wondering whether boosting this nocturnal detox could slow or even prevent disease.
Experiments range from using drugs and red-light therapy to inhaling bursts of carbon dioxide. There’s also talk of improving brain clearance by changing how we exercise or breathe, or even the position in which we sleep. Meanwhile, emerging techniques hint that we might already be able to gauge the health of our glymphatic system using a simple smartwatch.
Yet the young field has already been dogged by disputed methods, exaggerated headlines and the apparent detention of a key researcher. With so much at stake, it is vital to separate promise from hype, establishing what we can reliably measure, which interventions help clear the waste and whether doing so improves our health and prevents disease. All our cells produce unwanted chemicals that become harmful if they build up.
Luckily, we have an elaborate network of tubes called the lymphatic system that runs throughout the body, collecting fluid from cells, filtering it and sending it to the blood, with waste being expelled by the liver and kidneys. The strange thing is that there are no lymph vessels in the brain. The implication was that the brain’s waste molecules left passively, drifting through the extracellular fluid surrounding brain cells.
But this never made much sense for such an energy-hungry – and therefore heavily waste-creating – organ. The extraordinary influence of the lymphatic system on our health A breakthrough came in 2012, when Iliff and his colleagues injected a fluorescent tracer into the brains of living mice. They targeted the subarachnoid space, a thin region between two of the membranes, or meninges, that encase the brain and spinal cord.
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