![]() ![]() For a phenomenon so important, the purposes and mechanisms of sleep are only partially understood, so much so that as recently as the late 1990s it was quipped: "The only known function of sleep is to cure sleepiness". The importance of sleep is demonstrated by the fact that organisms daily spend hours of their time in sleep, and that sleep deprivation can have disastrous effects ultimately leading to death in animals. The study of sleep from a neuroscience perspective grew to prominence with advances in technology and the proliferation of neuroscience research from the second half of the twentieth century. Traditionally, sleep has been studied as part of psychology and medicine. The neuroscience of sleep is the study of the neuroscientific and physiological basis of the nature of sleep and its functions. PMID: 24136970.įunding: NIH’s National Institute of Neurological Disorders and Stroke (NINDS).Study of the neuroscientific and physiological basis of the nature of sleep Sleeping Princess: An early 20th-century painting by Victor Vasnetsov References: Sleep drives metabolite clearance from the adult brain. Alzheimer's Disease May Stem from Protein Clearance Problem.“Understanding precisely how and when the brain activates the glymphatic system and clears waste is a critical first step in efforts to potentially modulate this system and make it work more efficiently.” Related Links “These findings have significant implications for treating ‘dirty brain’ diseases like Alzheimer’s,” Nedergaard says. The study raises the possibility that certain neurological disorders might be prevented or treated by manipulating the glymphatic system. This result suggests a molecular connection between the sleep-wake cycle and the brain’s cleaning system. ![]() Treating mice with drugs that block noradrenaline induced a sleep-like state and increased brain fluid flow and extracellular brain volume. The researchers thus tested whether the hormone might affect the glymphatic system. The hormone noradrenaline, which increases alertness, is known to cause cells to swell. Glial cells control flow through the glymphatic system by shrinking and swelling. Beta-amyloid disappeared twice as quickly in the brains of mice that were asleep. The researchers next injected mice with labeled beta-amyloid and measured how long it lasted in their brains when they were asleep and awake. They found that this “extracellular” volume increased by 60% in the brain’s cortex when the mice were asleep or anesthetized. To test the idea, the team used a method that measures the volume of the space outside brain cells. In contrast, when the mice were unconscious - asleep or anesthetized - it flowed rapidly.Ĭhanges in the way fluid moves through the brain between conscious and unconscious states may reflect differences in the space available for movement. As reported in the October 18, 2013, edition of Science, the dye barely flowed when the mice were awake. The researchers first injected dye into the cerebrospinal fluid of mice and monitored electrical brain activity as they tracked the dye flow through the animals’ brains. The work was funded by NIH’s National Institute of Neurological Disorders and Stroke (NINDS). In their new study, the team tested the idea that sleep might affect beta-amyloid clearance by regulating the glymphatic system. ![]() Other research has shown that brain levels of beta-amyloid decrease during sleep. Beta-amyloid is renowned for accumulating in the brains of patients with Alzheimer's disease. The scientists also reported that the glymphatic system can help remove a toxic protein called beta-amyloid from brain tissue. The system is managed by the brain’s glial cells, and so the researchers called it the glymphatic system. Cerebrospinal fluid, a clear liquid surrounding the brain and spinal cord, moves through the brain along a series of channels that surround blood vessels. Maiken Nedergaard and her colleagues at the University of Rochester Medical Center recently discovered a system that drains waste products from the brain. However, the mechanisms behind these sleep benefits have been unknown.ĭr. ![]() Lack of sleep impairs reasoning, problem-solving, and attention to detail, among other effects. Scientists and philosophers have long wondered why people sleep and how it affects the brain. The results point to a potential new role for sleep in health and disease. Maiken NedergaardĪ mouse study suggests that sleep helps restore the brain by flushing out toxins that build up during waking hours. Cerebrospinal fluid (blue) flows through the brain and clears out toxins through a series of channels that expand during sleep. ![]()
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