By Mitch Leslie Scientists think sleep is the brain’s rinse cycle, when fluid percolating through the organ flushes out chemical waste that accumulated while we were awake. But what propels this circulation has been uncertain. A study of mice, reported today in Cell, suggests regular contractions of blood vessels in the brain, stimulated by the periodic release of a chemical cousin of adrenaline, push the fluid along. “This is excellent science,” says neuroscientist Suzana Herculano-Houzel of Vanderbilt University, who wasn’t connected to the study. “They put a number of pieces of evidence together that tell a pretty compelling story.” The scientists also found that the sleep drug zolpidem, better known as Ambien, impedes the blood vessel oscillations and the fluid flow they promote, implying it could hamper cleansing. The finding could help researchers create new sleep aids that preserve this brain-scrubbing function. The brain lacks the lymphatic vessels that collect and move fluid in other parts of the body. But in 2012, neuroscientist Maiken Nedergaard of the University of Rochester Medical Center and colleagues identified an alternative drainage system in which cerebrospinal fluid, the liquid bathing the brain, seeps through the organ via tiny passages alongside blood vessels, sweeping away metabolic refuse and other unwanted molecules. Fluid flow through this so-called glymphatic system ramps up during sleep, they also reported. Studies from 
Nedergaard’s group and others suggest vigorous glymphatic clearance is beneficial: Circulation falters in Alzheimer’s disease and other neurodegenerative illnesses. Some researchers have challenged parts of this picture, however; a 2024 study, for example, suggested waste clearance is actually faster during waking than during sleep. In the new research, Nedergaard and her team wanted to pin down what keeps cerebrospinal fluid moving through the brain. But studying the mouse glymphatic system often involves anesthetizing the rodents, she says, which is very different from natural sleep. To avoid this problem, the scientists surgically implanted mice with electrodes and fiber optic filaments. Although the rodents are tethered to a set of cables, they can fall asleep normally while researchers track blood volume, electrical activity, and chemical levels and use light transmitted through the fiber optic lines to activate certain groups of neurons.

Keyword: Sleep
Link ID: 29626 - Posted: 01.11.2025

By Traci Watson New clues have emerged in the mystery of how the brain avoids ‘catastrophic forgetting’ — the distortion and overwriting of previously established memories when new ones are created. A research team has found that, at least in mice, the brain processes new and old memories in separate phases of sleep, which might prevent mixing between the two. Assuming that the finding is confirmed in other animals, “I put all my money that this segregation will also occur in humans”, says György Buzsáki, a systems neuroscientist at New York University in New York City. That’s because memory is an evolutionarily ancient system, says Buzsáki, who was not part of the research team but once supervised the work of some of its members. The work was published on Wednesday in Nature1. Scientists have long known that, during sleep, the brain ‘replays’ recent experiences: the same neurons involved in an experience fire in the same order. This mechanism helps to solidify the experience as a memory and prepare it for long-term storage. To study brain function during sleep, the research team exploited a quirk of mice: their eyes are partially open during some stages of slumber. The team monitored one eye in each mouse as it slept. During a deep phase of sleep, the researchers observed the pupils shrink and then return to their original, larger size repeatedly, with each cycle lasting roughly one minute. Neuron recordings showed that most of the brain’s replay of experiences took place when the animals’ pupils were small. That led the scientists to wonder whether pupil size and memory processing are linked. To find out, they enlisted a technique called optogenetics, which uses light to either trigger or suppress the electrical activity of genetically engineered neurons in the brain. First, they trained engineered mice to find a sweet treat hidden on a platform. Immediately after these lessons, as the mice slept, the authors used optogenetics to reduce bursts of neuronal firing that have been linked to replay. They did so during both the small-pupil and large-pupil stages of sleep. © 2025 Springer Nature Limited

Keyword: Learning & Memory; Sleep
Link ID: 29615 - Posted: 01.04.2025

By Marla Broadfoot Everyone has heard that it’s vital to get seven to nine hours of sleep a night, a recommendation repeated so often it has become gospel. Get anything less, and you are more likely to suffer from poor health in the short and long term — memory problems, metabolic issues, depression, dementia, heart disease, a weakened immune system. But in recent years, scientists have discovered a rare breed who consistently get little shut-eye and are no worse for wear. Natural short sleepers, as they are called, are genetically wired to need only four to six hours of sleep a night. These outliers suggest that quality, not quantity, is what matters. If scientists could figure out what these people do differently it might, they hope, provide insight into sleep’s very nature. “The bottom line is, we don’t understand what sleep is, let alone what it’s for. That’s pretty incredible, given that the average person sleeps a third of their lives,” says Louis Ptáček, a neurologist at the University of California San Francisco. Scientists once thought sleep was little more than a period of rest, like powering down a computer in preparation for the next day’s work. Thomas Edison called sleep a waste of time — “a heritage from our cave days” — and claimed to never sleep more than four hours a night. His invention of the incandescent lightbulb encouraged shorter sleep times in others. Today, a historically high number of US adults are sleeping less than five hours a night. But modern sleep research has shown that sleep is an active, complicated process we don’t necessarily want to cut short. During sleep, scientists suspect that our bodies and brains are replenishing energy stores, flushing waste and toxins, pruning synapses and consolidating memories. As a result, chronic sleep deprivation can have serious health consequences.

Keyword: Sleep; Genes & Behavior
Link ID: 29603 - Posted: 12.14.2024

By Derek Thompson At 3 a.m. I’m jolted awake. The room is dark and still. I grab my phone and scan sports scores and Twitter. Still awake. A faceless physician whispers in my mind: To overcome middle-of-the-night insomnia, experts say you ought to get out of bed … I get out of bed. I pour a glass of water and drink it. I go back to bed. Still awake. Perhaps you know the feeling. Like millions of Americans and hundreds of millions of people around the world, I suffer from so-called mid-sleep awakenings that can keep me up for hours. One day, I was researching my nocturnal issues when I discovered a cottage industry of writers and sleep hackers who claim that sleep is a nightmare because of the industrial revolution, of all things. Essays in The Guardian, CNN, The New York Times, and The New York Times Magazine recommended an old fix for restlessness called “segmented sleep.” In premodern Europe, and perhaps centuries earlier, people routinely went to sleep around nightfall and woke up around midnight—only to go back to sleep a few hours later, until morning. They slept sort of like I do, but they were Zen about it. Then, the hackers claim, modernity came along and ruined everything by pressuring everybody to sleep in one big chunk. The romanticization of preindustrial sleep fascinated me. It also snapped into a popular template of contemporary internet analysis: If you experience a moment’s unpleasantness, first blame modern capitalism. So I reached out to Roger Ekirch, the historian whose work broke open the field of segmented sleep more than 20 years ago. In the 1980s, Ekirch was researching a book about nighttime before the industrial revolution. One day in London, wading through public records, he stumbled on references to “first sleep” and “second sleep” in a crime report from the 1600s. He had never seen the phrases before. When he broadened his search, he found mentions of first sleep in Italian (primo sonno), French (premier sommeil), and even Latin (primo somno); he found documentation in Africa, the Middle East, South Asia, and Latin America. © 2024 The Atlantic Monthly Group.

Keyword: Sleep
Link ID: 29595 - Posted: 12.11.2024

Andrew Gregory Health editor Failing to stick to a regular time for going to bed and waking up increases the risk of stroke, heart attack and heart failure by 26%, even for those who get a full night’s sleep, the most comprehensive study of its kind suggests. Previous studies have focused on the links between sleep duration and health outcomes, with people advised to get between seven and nine hours shut-eye a night. That advice still stands. But researchers are increasingly focusing on sleep patterns, and in particular the impact of irregular sleep – defined as variations in the time a person goes to sleep and wakes up. The new study found irregular sleep – going to bed and waking up at different times each day – was “strongly associated” with a higher risk of major adverse cardiovascular events. Even getting eight hours of sleep was insufficient to offset the harmful effects of consistently varying bed and wake-up times, experts said. The research, published in the Journal of Epidemiology and Community Health, involved 72,269 people aged 40 to 79 from the UK Biobank study. It did not establish precisely how close you have to get to the same bed and wake-up time – only that the further away you are, the higher the risk of harm. The lead author, Jean-Philippe Chaput, of the University of Ottawa, said: “We should aim to wake up and go to sleep within 30 minutes of the same time each night and each morning, including weekends. Within an hour of the same time is good but less good than 30 minutes, and even better is to have zero variation. “Beyond an hour’s difference each night and each morning means irregular sleep. That can have negative health impacts. The closer you are to zero variation the better. “No one is perfect across a whole year, and if you don’t have a regular sleep pattern for one or two days a week, it’s not going to kill you. But if you repeatedly have irregular sleep, five or six days a week, then it becomes chronic, and that is a problem.” Chaput said waking up at the same time each day was more important than going to bed at the same time. “Waking up at different times each morning really messes with your internal clock, and that can have adverse health consequences,” he said. © 2024 Guardian News & Media Limited

Keyword: Sleep
Link ID: 29578 - Posted: 11.27.2024

By Shaena Montanari In the Sterling Hall of Medicine at Yale University, a sign on a walk-in refrigerator door tells people to keep their voices down. Inside, about 250 ground squirrels are hibernating, each surrounded by shredded paper fluff and curled up in a clear plastic box. Shelves lined with these makeshift nests are bathed in red light that only the researchers can see, leaving the motionless animals in complete darkness. From about September to April—roughly the hibernation season for these thirteen-lined ground squirrels, which have stripes reminiscent of a chipmunk—the temperature inside the homemade hibernaculum is set at 4 degrees Celsius. The tiny rodents’ body temperature is the same as the chilly air, and their breathing and heart rates slow to just a handful of breaths and beats per minute—an energy-conserving response known as torpor. Scientists have studied this extreme physiological state for more than a century, says Elena Gracheva, whose bustling lab sits just outside the silent hibernaculum. But to date, they have focused mainly on physiological changes in individual peripheral organs that help an animal survive in cold temperatures. It is still unknown how the central nervous system regulates the process, she says. “We know a lot about physiology, but we don’t know the molecular basis.” Gracheva, professor of physiology and neuroscience at Yale University, is part of a small cadre of scientists who have set their sights on revealing those neural hibernation controls, using advanced tools to explore how the brain and other organ systems work together to maintain homeostasis. Their efforts are opening a “new era” in hibernation research, says Shona Wood, associate professor of Arctic chronobiology and physiology at the Arctic University of Norway. © 2024 Simons Foundation

Keyword: Sleep
Link ID: 29550 - Posted: 11.09.2024

By Lynne Peeples Living things began tracking the incremental passage of time long before the human-made clock lent its hands. As life grew in harmony with the sun’s daily march through the sky, and with the seasons, phases of the moon, tides, and other predictable environmental cycles, evolution ingrained biology with the timekeeping tools to keep a step ahead. It gifted an ability to anticipate changes, rather than respond to them, and an internal nudge to do things when most advantageous and to avoid doing things when not so advantageous. Of course, that optimal timing depended on a species’ niche on the 24-hour clock. When mammals first arose, for example, they were nocturnal — most active during the hours that the dinosaurs slept. Now mammals occupy both their choice territories on a spinning planet and their preferred space on a rotating clock. Timing is everything when it comes to seeking and digesting food, storing food, avoiding becoming food, dodging exposure to DNA-damaging ultraviolet radiation, and many more vital activities, such as navigating, migrating, and reproducing. Take the Eudyptula minor, a tiny penguin species that lives on Phillip Island in Australia. The slate-blue plumaged seabird speed waddles from the ocean to burrow home at the same “sun time” each day — just after sunset. Finding that precise window between day and night maximizes the penguins’ fishing time, allows them enough light to see their way to their burrows, and minimizes the chances they become visible food along the way for nighttime predators, such as orcas, seabirds, and feral cats. An internal clock off by just 10 minutes could prove fatal, one source told me. The island’s tourism industry capitalizes on this predictable “Penguin Parade.” A website lists approximate penguin arrival times for every month of the year and sells tickets to witness the spectacle. A higher ticket price grants visitors access to an underground viewing structure where they can watch the procession of waddlers at eye level. In October 2022, lucky visitors got to view a record-breaking 5,440 little penguins storm the shore and hurry home.

Keyword: Biological Rhythms
Link ID: 29549 - Posted: 11.09.2024

By Mariana Lenharo Immune cells rush to the brain and promote deep sleep after a heart attack, according to a new study1 involving both mice and humans. This heavy slumber helps recovery by easing inflammation in the heart, the study found. The findings, published today in Nature, could help to guide care for people after a heart attack, says co-author Cameron McAlpine at the Icahn School of Medicine at Mount Sinai in New York City, who studies immune function in the cardiovascular and nervous systems. “Getting sufficient sleep and rest after a heart attack is important for long-term healing of the heart,” he notes. The implications of the study go beyond heart attack, says Rachel Rowe, a specialist in sleep and inflammation at the University of Colorado Boulder. “For any kind of injury, your body’s natural response would be to help you sleep so your body can heal,” she says. Scientists have long known that sleep and cardiovascular health are linked. People who sleep poorly are at a higher risk of developing high blood pressure, for example, than are sound sleepers. But how cardiovascular disease affects sleep has been less explored. To learn more, the authors induced heart attacks in mice and investigated the animals’ brainwaves. The researchers found that these mice spent much more time in slow-wave sleep — a stage of deep sleep that has been associated with healing — than did mice that hadn’t had a heart attack. Next, the authors sought to understand what was causing that effect. One obvious place to look was the brain, which controls sleep, notes McAlpine. After a heart attack, immune cells trigger a massive burst of inflammation in the heart, he says, and the researchers wondered whether these immune changes also occurred in the brain. © 2024 Springer Nature Limited

Keyword: Sleep
Link ID: 29542 - Posted: 11.06.2024

By Maria Temming If you want to have a dream where you know you’re dreaming, you might be in luck. A phone app seems to boost users’ odds of having lucid dreams. Before bed, the app has users listen to a specific sound, such as a series of beeps, and practice associating that cue with a keen awareness of their thoughts and body. When the app plays that sound again six hours later, it’s meant to reactivate that self-awareness in the sleeping user, coaxing them to become lucid mid-dream. These types of sensory cues have proved fairly effective for inducing lucid dreams in sleep studies. But a researcher usually tracks someone’s sleep to play sounds during the REM stage, when lucid dreams are most likely. New experiments now show that a rough approximation of the technique using an app can promote lucid dreaming at home, researchers report in the October Consciousness and Cognition. This DIY approach might help more people have lucid dreams for recreation or research on the nature of consciousness (SN: 8/27/23). Researchers at Northwestern University in Evanston, Ill., built and tested the app. In one experiment, 19 people used it every night for a week. During the previous week, the group reported an average 0.74 lucid dreams. During the week of app use, that ramped up to an average 2.11 lucid dreams. “That’s a really big increase for lucid dreaming,” says Northwestern cognitive neuroscientist Karen Konkoly. “Lucid dreaming once a week is a lot.” But it wasn’t completely clear that the app’s sound cues led to that increase. “It could be that just focusing on lucid dreaming for a week or expectations or something was responsible,” Konkoly says. So the team ran another experiment with 112 people. © Society for Science & the Public 2000–2024.

Keyword: Sleep
Link ID: 29541 - Posted: 11.06.2024

By Emily Schmall It’s time to change the clocks again, and getting out of bed may feel harder than usual: Research has shown the sudden shift can be disruptive to sleep. But for many adults in the United States, sleep deprivation is a year-round problem that can affect both their physical and mental health. Research suggests that chronic poor sleep raises your risk of cardiovascular disease, high blood pressure and metabolic issues, and can make you more prone to infections. Some long-term studies have also linked a lack of sleep to depression, anxiety and other mental health disorders. Getting enough sleep, on the other hand, can reduce stress, sharpen attention and even bolster our immune systems. You don’t need to miss out on a lot of sleep every night to experience negative health effects. If a person is consistently getting even 15 minutes less sleep than they need to function well, experts said, that can be considered sleep deprivation. How common is sleep deprivation? Ideally, adults should aim for seven to nine hours of sleep every night, according to the Centers for Disease Control and Prevention. Yet, about one in three adults in the United States logs less than seven hours of sleep a day. Studies suggest that insufficient sleep has become more common in recent decades, in part because Americans work longer hours and spend more time on blue-light-generating computers and phones that can affect their ability to sleep. Blue light, like the sun’s rays, sets off brain receptors that are designed to keep us awake. “As we become more and more plugged in, this becomes more and more of an issue,” said Dr. Charlene Gamaldo, a professor of neurology at Johns Hopkins University School of Medicine. Generally speaking, experts consider someone sleep-deprived if that person gets less sleep than needed or not enough quality sleep for several days a week over several months, Dr. Gamaldo said. Not sleeping enough within the ideal window for your biological clock — for most people, that is between 11 p.m. and 7 a.m., but it can vary — can result in lower-quality rest, causing sleep deprivation, she said. © 2024 The New York Times Company

Keyword: Sleep
Link ID: 29540 - Posted: 11.06.2024

By Christina Caron It’s not uncommon for our minds to unleash a torrent of difficult feelings under the cover of darkness: sadness and negative thoughts may surface at night, making sleep hard to come by. On social media and elsewhere people often refer to this as “nighttime depression.” But is that really a thing? And if so, why do some people get blue at night? Feeling down after dusk doesn’t necessarily mean that you have a mental health condition, experts said. Understanding why it happens can help you take steps to feel better. What is nighttime depression? Nighttime depression is a colloquial term for depressive symptoms that either appear or worsen late at night. It is not itself a diagnosis. While anxiety can also ramp up at night, and tends to make people feel agitated, tense and restless, nighttime depression is best characterized as a low mood. “It’s a sense of sadness,” said Dr. Theresa Miskimen Rivera, a clinical professor of psychiatry at Rutgers University and president-elect of the American Psychiatric Association. “It’s that feeling of: There’s no joy. My life is so blah.” Nighttime depression can also feel uncomfortable — “not only in your mind, but in your body,” Dr. Rivera added, especially if these feelings interfere with getting enough sleep. © 2024 The New York Times Company

Keyword: Depression; Sleep
Link ID: 29506 - Posted: 10.05.2024

Anna Bawden Health and social affairs correspondent An epilepsy drug could help prevent the breathing of patients with sleep apnoea from temporarily stopping, according to research. Obstructive sleep apnoea is a common breathing problem that affects about one in 20 people, according to the National Institute for Health and Care Excellence in England. Patients often snore loudly, their breathing starts and stops during the night and they may wake up several times. Not only does this cause tiredness but it can also increase the risk of high blood pressure, stroke, heart disease and type 2 diabetes. An international study has identified that an epilepsy medication is associated with a marked reduction in sleep apnoea symptoms. The findings, presented at the European Respiratory Society Congress in Vienna, Austria, demonstrated there were possible options for those unable to use mechanical breathing aids such as continuous positive airway pressure (Cpap) machines. Prof Jan Hedner, from Sahlgrenska university hospital and the University of Gothenburg in Sweden, said: “The standard treatment for obstructive sleep apnoea is sleeping with a machine that blows air through a face mask to keep the airways open. Unfortunately, many people find these machines hard to use over the long term, so there is a need to find alternative treatments.” The researchers conducted a randomised controlled trial of almost 300 obstructive sleep apnoea patients in Belgium, the Czech Republic, France, Germany and Spain who did not use the Cpap machines. They were divided into four groups and given one of three strengths of sulthiame or a placebo. © 2024 Guardian News & Media Limited

Keyword: Sleep
Link ID: 29474 - Posted: 09.11.2024

By Kevin Loria When you have obstructive sleep apnea, addressing it is key. Left untreated, sleep apnea is linked to daytime sleepiness and an increased risk of anxiety, diabetes, hypertension and stroke. With OSA, your breathing pauses during sleep because your tongue or relaxed throat muscles block your airway, explains Richard Schwab, chief of the division of sleep medicine at the University of Pennsylvania Perelman School of Medicine in Philadelphia. Losing weight, quitting smoking and limiting alcohol can all help ease obstructive sleep apnea symptoms such as snoring, says Ana Krieger, medical director of the Center for Sleep Medicine at Weill Cornell Medicine in New York City. Sleep apnea’s severity is determined by something called your apnea-hypopnea index (AHI): the number of times per hour you fully or partially stop breathing for 10 seconds or longer. The primary treatment for people with moderate (15 to 29 AHI) or severe (30 AHI and higher) obstructive sleep apnea is a continuous positive airway pressure (CPAP) machine, which keeps your airway open by pumping air through a mask you wear over your mouth and/or nose when you sleep. Many people have difficulty tolerating a CPAP and don’t stick with it, however. The good news is CPAP machines have become smaller and quieter, with more comfortable options available. And for some people with mild (5 to 14 AHI) or even moderate OSA, less-invasive alternatives to a CPAP may be worth considering. A dental device designed to move the jaw so that the tongue shifts toward the front of the mouth can help keep the airway open. It’s one of the primary alternatives to a CPAP, Schwab says, and can also be used with a CPAP to help make severe obstructive sleep apnea milder.

Keyword: Sleep
Link ID: 29460 - Posted: 09.04.2024

Tobi Thomas People who “catch up” on missed sleep at the weekend may have up to a 20% lower risk of heart disease compared with those who do not, according to a study. The findings, presented at a meeting of the European Society of Cardiology, looked at data from 90,903 adults taking part in the UK Biobank project, a database that holds medical and lifestyle records of 500,000 people in the UK. Of these, 19,816 met the criteria for being sleep-deprived, and over a follow-up period of 14 years the researchers found that the people who had the most extra sleep during the weekends were 19% less likely to develop heart disease than those who had the least amount of sleep at the weekends. Sleep deprivation in the study has been defined as those who self-reported having had less than seven hours of sleep per night. The video player is currently playing an ad. Those who got extra sleep at weekends ranged from an additional 1.28 hours to 16.06 hours, and those with the least sleep were losing 16.05 hours to 0.26 hours over the weekend. The study also looked at a sub-group of people with daily sleep deprivation and found that those who had the most compensatory sleep at the weekend had a 20% lower risk of developing heart disease than those with the least. Although the rest of the participants included in the study may have experienced inadequate sleep, on average their daily hours of sleep did not meet the criteria for being sleep deprived. Prof Yanjun Song, the study’s author, of China’s National Centre for Cardiovascular Disease in Beijing, said: “Sufficient compensatory sleep is linked to a lower risk of heart disease. The association becomes even more pronounced among individuals who regularly experience inadequate sleep on weekdays.” © 2024 Guardian News & Media Limited

Keyword: Sleep
Link ID: 29455 - Posted: 08.31.2024

Linda Geddes Imagine a world in which you could solve problems, create art or music or even improve your tennis serve in your sleep. If scientists working in the field of lucid dreams succeed, that world could become a reality sooner than we realise. Researchers are developing techniques that could enable more people to experience lucid dreams – a state of consciousness where a person is aware they are dreaming and can recognise their thoughts and emotions while doing so – and transfer the content of these dreams into their waking lives. They have shown in recent months that it is possible to transfer the rhythm of dream music, switch on a real-life kettle and control a virtual car on a computer screen from inside a lucid dream. “Sooner or later there will be methods or tools that will allow anybody to experience lucid dreams easily or relatively easily, we are searching for ways to connect these two worlds together,” said Michael Raduga, the founder and CEO of REMspace Inc, a sleep research company in Redwood City, California who led the studies. “Even for people who don’t think they are smart, their subconscious is enormous, and we hope to be able to transfer all of this information into reality.” The video player is currently playing an ad. Although not everyone can do it, roughly half of the population have experienced at least one lucid dream in their lifetimes and around a fifth experience them once a month or more. An international group of researchers published a paper in Current Biology several years ago that suggested it was possible to ask people questions, either vocally or using morse code delivered via flashing lights, while they were in a lucid dream – including basic mathematical calculations – and for the dreamers to answer using eye movements or by contracting facial muscles to convey yes/no or numerical answers. © 2024 Guardian News & Media Limited

Keyword: Sleep
Link ID: 29439 - Posted: 08.19.2024

By Catherine Offord Lack of sleep wreaks havoc on the brain, making us worse learners and disrupting our memory, among other insults. Now, a study in mice suggests some of these effects could stem from changes in how brain cells are connected to one another. In a paper published today in Current Biology, researchers show that just hours of sleep deprivation reduce how many different types of synapses—the places where neurons meet—there are in brain regions associated with learning and memory. The findings hint at a novel way sleep might help keep us sharp, the team says. The study “is a technical tour de force,” says Marcos Frank, a neuroscientist at Washington State University who was not involved in the work. Still, he and others caution it’s not yet clear whether this result explains sleep deprivation’s unpleasant side effects. Nerve cells meet and communicate via chemicals across synapses, allowing signals to travel through the nervous system. There are trillions such connections in the human brain, forming and rearranging circuits of neurons that capture and store information. Various theories have tried to invoke these connections to explain the relationship between sleep and memory. One well-known idea from the early 2000s holds that the strength of synapses in the brain decreases when we sleep, and that this is important for conserving energy and prepping the brain for encoding new information the following day. But such theories often treat synapses as relatively uniform, says Seth Grant, a neuroscientist at the University of Edinburgh. In the past few years, his team and others have found that synapses are surprisingly diverse. They differ not only in the types of chemical, or neurotransmitter, they use to send signals, but in structure and in the composition of proteins present in the neurons surrounding them.

Keyword: Sleep
Link ID: 29422 - Posted: 08.03.2024

Oscar Allan The sluggish start to the day, the struggle to concentrate on everyday tasks and the lethargy that comes with just a few hours sleep, these are the symptoms that will be familiar to anyone who suffers with insomnia. But according to research, not all sleepless nights are the same. Brain scans have revealed evidence for distinct forms of insomnia, each with an associated pattern of neural wiring. And while the clinical distinction may mean little to those whose days are blighted by sleep deprivation, the discovery does raise the prospect of tailored interventions for people with different kinds of insomnia, which could lead to better treatments. Researchers at the Netherlands Institute for Neuroscience in Amsterdam analysed MRI scans from more than 200 insomniacs and dozens of sound sleepers and spotted structural changes that distinguished sleepers from the sleepless and five separate forms of insomnia. “If these subtypes differ in their biological mechanism, then patients in each subtype might benefit from different focused treatments,” said Tom Bresser, a neuroscientist and first author on the study. Insomnia is broadly defined as poor sleep, generally due to difficulties falling or staying asleep, which negatively affects daytime functioning. About a third of adults in western countries have sleep problems at least once a week, with up to 10% qualifying for a formal insomnia diagnosis. Chronic insomnia is diagnosed if someone suffers sleep problems on at least three nights a week for three months or more. The condition is nearly twice as common in women than men. © 2024 Guardian News & Media Limited

Keyword: Sleep
Link ID: 29401 - Posted: 07.23.2024

By Dana G. Smith Getting too little sleep later in life is associated with an increased risk for Alzheimer’s disease. But paradoxically, so is getting too much sleep. While scientists are confident that a connection between sleep and dementia exists, the nature of that connection is complicated. It could be that poor sleep triggers changes in the brain that cause dementia. Or people’s sleep might be disrupted because of an underlying health issue that also affects brain health. And changes in sleep patterns can be an early sign of dementia itself. Here’s how experts think about these various connections and how to gauge your risk based on your own sleep habits. Too Little Sleep Sleep acts like a nightly shower for the brain, washing away the cellular waste that accumulates during the day. During this process, the fluid that surrounds brain cells flushes out molecular garbage and transfers it into the bloodstream, where it’s then filtered by the liver and kidneys and expelled from the body. That trash includes the protein amyloid, which is thought to play a key role in Alzheimer’s disease. Everyone’s brain produces amyloid during the day, but problems can arise when the protein accumulates into sticky clumps, called plaques. The longer someone is awake, the more amyloid builds up and the less time the brain has to remove it. Scientists don’t know whether regularly getting too little sleep — typically considered six hours or less a night — is enough to trigger the accumulation of amyloid on its own. But research has found that among adults aged 65 to 85 who already have plaques in their brains, the less sleep they got, the more amyloid was present and the worse their cognition. “Is lack of sleep sufficient to cause dementia? Probably not by itself alone,” said Dr. Sudha Seshadri, the founding director of the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases at the University of Texas Health Science Center at San Antonio. “But it seems to definitely be a risk factor for increasing the risk of dementia, and perhaps also the speed of decline.” © 2024 The New York Times Company

Keyword: Sleep; Alzheimers
Link ID: 29400 - Posted: 07.23.2024

Anna Bawden The idea that night owls who don’t go to bed until the early hours struggle to get anything done during the day may have to be revised. It turns out that staying up late could be good for our brain power as research suggests that people who identify as night owls could be sharper than those who go to bed early. Researchers led by academics at Imperial College London studied data from the UK Biobank study on more than 26,000 people who had completed intelligence, reasoning, reaction time and memory tests. They then examined how participants’ sleep duration, quality, and chronotype (which determines what time of day we feel most alert and productive) affected brain performance. They found that those who stay up late and those classed as “intermediate” had “superior cognitive function”, while morning larks had the lowest scores. Going to bed late is strongly associated with creative types. Artists, authors and musicians known to be night owls include Henri de Toulouse-Lautrec, James Joyce, Kanye West and Lady Gaga. But while politicians such as Margaret Thatcher, Winston Churchill and Barack Obama famously seemed to thrive on little sleep, the study found that sleep duration is important for brain function, with those getting between seven and nine hours of shut-eye each night performing best in cognitive tests. © 2024 Guardian News & Media Limited

Keyword: Biological Rhythms; Learning & Memory
Link ID: 29389 - Posted: 07.11.2024

Jon Hamilton About 170 billion cells are in the brain, and as they go about their regular tasks, they produce waste — a lot of it. To stay healthy, the brain needs to wash away all that debris. But how exactly it does this has remained a mystery. Now, two teams of scientists have published three papers that offer a detailed description of the brain's waste-removal system. Their insights could help researchers better understand, treat and perhaps prevent a broad range of brain disorders. The papers, all published in the journal Nature, suggest that during sleep, slow electrical waves push the fluid around cells from deep in the brain to its surface. There, a sophisticated interface allows the waste products in that fluid to be absorbed into the bloodstream, which takes them to the liver and kidneys to be removed from the body. One of the waste products carried away is amyloid, the substance that forms sticky plaques in the brains of patients with Alzheimer's disease. This illustration demonstrates how the thin film of sensors could be applied to the brain during surgery. There's growing evidence that in Alzheimer's disease, the brain's waste-removal system is impaired, says Jeffrey Iliff, who studies neurodegenerative diseases at the University of Washington but was not a part of the new studies. The new findings should help researchers understand precisely where the problem is and perhaps fix it, Iliff says. "If we restore drainage, can we prevent the development of Alzheimer's disease?" he asks. The new studies come more than a decade after Iliff and Dr. Maiken Nedergaard, a Danish scientist, first proposed that the clear fluids in and around the brain are part of a system to wash away waste products. The scientists named it the glymphatic system, a nod to the body's lymphatic system, which helps fight infection, maintain fluid levels and filter out waste products and abnormal cells. © 2024 npr

Keyword: Sleep
Link ID: 29369 - Posted: 06.26.2024