The rhythmic waves of blood and cerebrospinal fluid (CSF) that occur when we are sleeping, appear to function much like a washing machine’s rinse cycle, which may help to clear the brain of toxic waste on a regular basis.
Every 20 seconds, a wave of fresh cerebrospinal fluid rolls into the sleeping brain. These slow, rhythmic blasts, described for the first time in the Nov. 1 Science, may help explain why sleep is so important for brain health.
Studies on animals have shown that the fluid, called CSF, can wash harmful proteins, including those implicated in Alzheimer’s disease, out of the brain. The new results give heft to the idea that a similar power wash happens in sleeping people.
The findings, published recently in the journal Science, are the first to suggest that the brain’s well-known ebb and flow of blood and electrical activity during sleep may also trigger cleansing waves of blood and CSF. While the experiments were conducted in healthy adults, further study of this phenomenon may help explain why poor sleep or loss of sleep has previously been associated with the spread of toxic proteins and worsening memory loss in people with Alzheimer’s disease.
From Science News via YouTube »
During non-REM sleep, oxygen-rich blood (colored red) flows out of the brain just before a wave of cerebrospinal fluid (blue) rolls in, entering from a lower part called the fourth ventricle. That cerebrospinal fluid may help clean harmful proteins out of the brain.
A third of people in the UK get less than the recommended 7-9 hours a night, according to the National Sleep Foundation. But ostrich pillows, nap pods, wearable devices and sleep robots can all supposedly help. The FT’s Daniel Garrahan tests out some of the latest sleep solutions.
How well we sleep impacts how we think and feel, as well as our alertness, memory, and concentration. “Sleep quality and quantity are directly related to the health of the brain,” says Beth A. Malow, MD, MS, FAAN, professor of neurology and director of the sleep disorders division at Vanderbilt University Medical Center in Nashville. Several studies have demonstrated an association between sleep disturbances such as insomnia, fragmented sleep, sleep apnea, and even excessive napping and an increased risk of cognitive decline over time, says Brendan P. Lucey, MD, assistant professor of neurology and director of the sleep medicine section at Washington University School of Medicine in St. Louis.
In 2009, a series of studies on mice conducted at Washington University were among the first to suggest that chronically sleep-deprived subjects develop higher levels of harmful amyloid beta and tau proteins—considered, along with neurofibrillary tangles, to be hallmarks of Alzheimer’s disease. “Think of tau and amyloid as the waste produced by typical nerve function,” says Charlene Gamaldo, MD, FAAN, associate professor of neurology and medical director of the Johns Hopkins Sleep Disorders Center. “Normally, the brain clears these metabolic waste products away.”
And it may clear away these proteins during sleep, according to a landmark 2013 rodent study in Science by researchers at the University of Rochester Medical Center, who showed that during deep sleep, when neural activity quiets down, cerebrospinal fluid (CSF) bathes the brain, washing away excess amyloid beta and tau proteins. A more recent study, published in the November 2019 issue of iScience, provided further insight into CSF’s function. MRI scans taken while subjects were sleeping showed that during deep sleep, blood flow in the brain diminished as pulsing waves of CSF flushed out excess amyloid beta and tau, presumably girding the brain against cognitive decline. So while it has been known that sleep has some value for survival, these reports seem to put sleep front and center in terms of protecting us from cognitive decline.
Long-term sleep disruptions may raise the risk of some cancers. But sleep and cancer are intertwined in other ways too. Getting a good night’s sleep is difficult during cancer treatment and can be a lifelong challenge for survivors.
“In our research, nearly one in four survivors of childhood cancer had difficulty falling asleep and staying asleep,” says cancer expert Kathryn Ruble, M.S.N., Ph.D. , of the Johns Hopkins Kimmel Cancer Center . “Helping cancer survivors improve their sleep might help them perform at school, on the job, and throughout their lives.”
Disruptions in the body’s “biological clock,” which controls sleep and thousands of other functions, may raise the odds of cancers of the breast, colon, ovaries and prostate. Exposure to light while working overnight shifts for several years may reduce levels of melatonin, encouraging cancer to grow.
Sleep is your life-support system and Mother Nature’s best effort yet at immortality, says sleep scientist Matt Walker. In this deep dive into the science of slumber, Walker shares the wonderfully good things that happen when you get sleep — and the alarmingly bad things that happen when you don’t, for both your brain and body. Learn more about sleep’s impact on your learning, memory, immune system and even your genetic code — as well as some helpful tips for getting some shut-eye.
Researchers have found that the type of sleep most apt to calm and reset the anxious brain is deep sleep, also known as non-rapid eye movement (NREM) slow-wave sleep, a state in which neural oscillations become highly synchronized, and heart rates and blood pressure drop.
“We have identified a new function of deep sleep, one that decreases anxiety overnight by reorganizing connections in the brain,” said study senior author Matthew Walker, a UC Berkeley professor of neuroscience and psychology. “Deep sleep seems to be a natural anxiolytic (anxiety inhibitor), so long as we get it each and every night.”
The findings, published this month in the journal Nature Human Behaviour, provide one of the strongest neural links between sleep and anxiety to date. They also point to sleep as a natural, non-pharmaceutical remedy for anxiety disorders, which have been diagnosed in some 40 million American adults and are rising among children and teens.
All of 2,300 employees working at Microsoft Japan had three-day weekends in August this year, as part of the company’s ‘Work Life Choice Challenge.’
Getting an extra day off every week made for improvements in several areas, including productivity and operational costs. Sales per employee, used to determine productivity, rose by 39.9 percent as compared to figures in August 2018, while remaining closed for an extra day reduced the firm’s electricity costs by 23.1 percent and saw a 58.7 percent decline in paper printing.
Given that employees had only four days to work, meetings were capped at 30 minutes, while remote conferences were increased to eliminate commuting where possible. The experiment also incorporated self-development and family wellness schemes and received positive feedback by the majority of employees, 92.1 percent of whom liked the shorter workweek.
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