Your brain works hard all day, processing information that comes in at a staggering rate of 1 billion bits per second. It’s no wonder, then, that it needs some downtime to freshen up. Scientists have long theorized that humans and other animals need sleep because it helps maintain the brain, but they’ve also discovered that, during sleep, the brain is literally washed with fluid in a sort of rinse cycle that clears out chemical waste.
A waste clearance network called the glymphatic system is responsible for this brain rinse, which is thought to happen largely when we’re asleep. Unlike other parts of the body, the brain doesn’t have lymphatic vessels to help it move fluids around. However, it does seem to have developed a work-around: In a study with mice, researchers found that blood volume and cerebrospinal fluid levels varied in response to pulses of norepinephrine, a neurotransmitter found in the brain that regulates alertness and affects your sleep-wake cycle, among other things.
Norepinephrine pulses cause the brain’s blood vessels to clench — and, with the hard wall of the skull creating resistance, that clenching action creates a pumping effect. Cerebrospinal fluid moves in to fill the gap made by the clenching vessels. When the blood vessels relax, the fluid is moved out again, carrying away waste.
Media Release/InterestingFacts
