'Body clock' rhythms, not sleep, control brain waste disposal

This may explain their increased risk of brain disorders, such as Alzheimer’s disease.In 2012, researchers at the University of Rochester Medical Center (URMC), NY, discovered a previously unknown waste disposal system in the brain.They dubbed it the glymphatic system because nerve cells called glial cells manage its operation, which fulfills a similar role for the brain that the lymphatic system does for the rest of the body.The following year, the same team found that the glymphatic system is most active during sleep.In their latest experiments, the researchers reveal that it is the body’s circadian rhythms, the “master clock” regulating the sleep-wake cycle of roughly 24 hours, that governs this system.“These findings show that glymphatic system function is not solely based on sleep or wakefulness, but by the daily rhythms dictated by our biological clock,” says neuroscientist Dr. Maiken Nedergaard, co-director of the Center for Translational Neuromedicine at URMC and senior author of the study.The findings appear in the journal Nature Communications.One of the processes that occur during sleep is the clearance of toxic products of metabolism that accumulate in the brain during wakefulness.