Chapter 10. Biological Rhythms and Sleep

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By Siddhant Pusdekar In the deepest stage of sleep, slow waves of electrical activity travel through your brain. They help consolidate memories and flush out the buildup of unwanted chemicals, getting you ready for the day. This midnight orchestra is responsible for many of the benefits of a good night’s sleep, such as improved attention, mood and energy levels. Scientists at the University of California, Berkeley, recently found that for some people, these waves could also serve as early warning signs of diabetes. The results, published in July in Cell Reports Medicine, suggest that getting a restful sleep may help control high blood sugar. People with type 2 diabetes are unable to metabolize sugar, leading to a damaging excess concentration in the blood. The approximately 515 million people globally with type 2 diabetes can manage blood sugar through diet, exercise and medications such as insulin. But researchers and clinicians have observed that quality of sleep seems to influence blood sugar, too. “We have known that something magic happens during sleep,” says New York University neuroscientist Gyorgy Buzsaki about the links between sleep and metabolism. Yet the mechanism behind that relationship has been a mystery, he says. To investigate, the July study’s co-lead author Raphael Vallat, then a postdoctoral researcher at U.C. Berkeley, analyzed blood glucose and sleep measurements from two large independent public datasets. In the first analysis, Vallat and his colleagues examined sleep patterns measured from polysomnography, a standard assessment that doctors recommend for people with sleep problems. The procedure, typically conducted at night, involves placing a bunch of wires on different parts of the head to record activity in specific brain regions. The ends of the wires act like “microphones” that “hear” brain waves, explains Vyoma Shah, a graduate student at U.C. Berkeley and co-lead author of the paper. Squiggles of different shapes and sizes on the polysomnography graphs represent the ebbs and flows of electrical activity in people’s head as they sleep throughout the night. It is only a surface-level view, however. © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep; Obesity
Link ID: 29035 - Posted: 12.09.2023

By Jake Buehler Nesting chinstrap penguins take nodding off to the extreme. The birds briefly dip into a slumber many thousands of times per day, sleeping for only seconds at a time. The penguins’ breeding colonies are noisy and stressful places, and threats from predatory birds and aggressive neighbor penguins are unrelenting. The extremely disjointed sleep schedule may help the penguins to protect their young while still getting enough shut-eye, researchers report in the Dec. 1 Science. The findings add to evidence “that avian sleep can be very different from the sleep of land mammals,” says UCLA neuroscientist Jerome Siegel. Nearly a decade ago, behavioral ecologist Won Young Lee of the Korea Polar Research Institute in Incheon noticed something peculiar about how chinstrap penguins (Pygoscelis antarcticus) nesting on Antarctica’s King George Island were sleeping. They would seemingly doze off for very short periods of time in their cacophonous colonies. Then in 2018, Lee learned about frigate birds’ ability to steal sleep while airborne on days-long flights. Lee teamed up with sleep ecophysiologist Paul-Antoine Libourel of the Lyon Neuroscience Research Center in France and other researchers to investigate the penguins’ sleep. In 2019, the team studied the daily sleep patterns of 14 nesting chinstrap penguins using data loggers mounted on the birds’ backs. The devices had electrodes surgically implanted into the penguins’ brains for measuring brain activity. Other instruments on the data loggers recorded the animals’ movements and location. Nesting penguins had incredibly fragmented sleep patterns, taking over 600 “microsleeps” an hour, each averaging only four seconds, the researchers found. At times, the penguins slept with only half of their brain; the other half stayed awake. All together, the oodles of snoozes added up, providing over 11 hours of sleep for each brain hemisphere across more than 10,000 brief sleeps each day. © Society for Science & the Public 2000–2023.

Keyword: Sleep; Evolution
Link ID: 29028 - Posted: 12.02.2023

By Erin Garcia de Jesús A new brain-monitoring device aims to be the Goldilocks of anesthesia delivery, dispensing drugs in just the right dose. No physician wants a patient to wake up during surgery — nor do patients. So anesthesiologists often give more drug than necessary to keep patients sedated during medical procedures or while on lifesaving machines like ventilators. But anesthetics can sometimes be harmful when given in excess, says David Mintz, an anesthesiologist at Johns Hopkins University. For instance, elderly people with cognitive conditions like dementia or age-related cognitive decline may be at higher risk of post-surgical confusion. Studies also hint that long periods of use in young children might cause behavioral problems. “The less we give of them, the better,” Mintz says. An automated anesthesia delivery system could help doctors find the right drug dose. The new device monitored rhesus macaques’ brain activity and supplied a common anesthetic called propofol in doses that were automatically adjusted every 20 seconds. Fluctuating doses ensured the animals received just enough drug — not too much or too little — to stay sedated for 125 minutes, researchers reported October 31 in PNAS Nexus. The study is a step toward devising and testing a system that would work for people. © Society for Science & the Public 2000–2023.

Keyword: Consciousness; Pain & Touch
Link ID: 29021 - Posted: 11.26.2023

By Timmy Broderick Smell is probably our most underappreciated sense. “If you ask people which sense they would be most willing to give up, it would be the olfactory system,” says Michael Leon, a neurobiologist at the University of California, Irvine. But a loss of smell has been linked to health complications such as depression and cognitive decline. And mounting evidence shows that olfactory training, which involves deliberately smelling strong scents on a regular basis, may help stave off that decline. Now a team of researchers led by Leon has successfully boosted cognitive performance by exposing people to smells while they sleep. Twenty participants—all older than 60 years and generally healthy—received six months of overnight olfactory enrichment, and all significantly improved their ability to recall lists of words compared with a control group. The study appeared in Frontiers in Neuroscience. The scientists are unsure about how the overnight odors may have produced this result, but Leon notes that the neurons involved in olfaction have “direct superhighway access” to brain regions related to memory and emotion. In participants who received the treatment, the study authors observed physical changes in a brain structure that connects the memory and emotional centers—a pathway that often deteriorates as people age, especially in those with Alzheimer's disease. Previous successful attempts to boost memory with odors typically relied on complicated interventions with multiple exposures a day. If the nighttime treatment proves successful in larger trials, it promises to be a less intrusive way to achieve similar effects, says Vidya Kamath, a neuropsychologist at the Johns Hopkins University School of Medicine, who was not involved in the recent study. Larger trials may also help answer some remaining questions. The new study used widely available essential oils such as rose and eucalyptus, but researchers aren't sure if just any odor would get the same results. They don't know how much an odor's qualities—whether it's foul or pleasant to people, for example—affects the cognitive gains. It is also unclear how much novelty plays a role, says Michał Pieniak, a psychology researcher at the University of Wroclaw in Poland who has studied olfactory training. © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep; Learning & Memory
Link ID: 29010 - Posted: 11.18.2023

Sean O'Donnell Human-driven climate change is increasingly shaping the Earth’s living environments. Rising temperatures, rapid shifts in rainfall and seasonality, and ocean acidification are presenting altered environments to many animal species. How do animals adjust to these new, often extreme, conditions? Animal nervous systems play a central role in both enabling and limiting how they respond to changing climates. Two of my main research interests as a biologist and neuroscientist involve understanding how animals accommodate temperature extremes and identifying the forces that shape the structure and function of animal nervous systems, especially brains. The intersection of these interests led me to explore the effects of climate on nervous systems and how animals will likely respond to rapidly shifting environments. All major functions of the nervous system – sense detection, mental processing and behavior direction – are critical. They allow animals to navigate their environments in ways that enable their survival and reproduction. Climate change will likely affect these functions, often for the worse. Changing temperatures shift the energy balance of ecosystems – from plants that produce energy from sunlight to the animals that consume plants and other animals – subsequently altering the sensory worlds that animals experience. It is likely that climate change will challenge all of their senses, from sight and taste to smell and touch. Animals like mammals perceive temperature in part with special receptor proteins in their nervous systems that respond to heat and cold, discriminating between moderate and extreme temperatures. These receptor proteins help animals seek appropriate habitats and may play a critical role in how animals respond to changing temperatures.

Keyword: Biological Rhythms
Link ID: 29007 - Posted: 11.15.2023

By Jocelyn Solis-Moreira When the alarm goes off in the early morning, it’s tempting to hit the snooze button and curl back under the warm covers for a few more minutes of slumber. This repeated postponing of the buzzer is often thought of as a bad habit—one that creates not only a lazy start to a day but also a fragmented sleep pattern that’s detrimental to health. Now, however, a growing body of recent research is contradicting this notion. A new study published in the Journal of Sleep Research found that people who regularly press the snooze button lost only about six minutes of sleep per night—and that it didn’t affect their morning sleepiness or mood. In fact, tests showed that it actually improved cognition. This adds to research in 2022 that also found chronic snoozers generally felt no sleepier than nonsnoozers. “Snoozing for a limited time in the morning is probably not bad for you,” says the new study’s lead author Tina Sundelin, a sleep researcher at Stockholm University. She says that her study is one of few that have directly tested snoozing’s effect on sleep health, and it supplies evidence that snoozing doesn’t break up sleep in a harmful way. Scientific American spoke with sleep experts on the science of snoozing and how the habit may actually be good for you—if you do it right. The Potential Benefits of Snoozing Snoozing does shorten sleep, Sundelin says, but she maintains that it’s not as bad as scientists once thought. Past research has suggested that the extra minutes snoozers get don’t really help them feel more rested—and repeatedly waking up and trying to sleep again has been thought to prevent the restorative stages of sleep, including rapid-eye movement (REM). Other research has suggested that waking someone in the middle of their sleep cycle causes them to feel sleepier throughout the day. “If you disturb someone’s sleep, it’s not good-quality sleep, and they often feel tired afterwards—but this [idea] is based on a whole night of sleep fragmentation,” explains Sundelin, who adds that most theories about snoozing are “inferred from what we know about sleep in general.” © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep
Link ID: 29005 - Posted: 11.15.2023

Catherine Sweeney - WPLN NASHVILLE, Tenn. — High school classes start so early around this city that some kids get on buses at 5:30 in the morning. Just 10% of public schools nationwide start before 7:30 a.m., according to federal statistics. But in Nashville, classes start at 7:05 — a fact the new mayor, Freddie O'Connell, has been criticizing for years. "It's not a badge of honor," he said when he was still a city council member. Since his election in September, O'Connell has announced that pushing back school start times is a cornerstone of the education policy he is promoting. He and others around the country have been trying to stress that teenagers aren't lazy or to blame for getting too little sleep. It's science. Sponsor Message "All teenagers have this shift in their brain that causes them to not feel sleepy until about 10:45 or 11 at night," said Kyla Wahlstrom, a senior research fellow at the University of Minnesota in the College of Education and Human Development. She studies how education policy affects learning, and she used to be a teacher. "It's a shift that is biologically determined." Sleep deprivation in teenagers is linked to mental health struggles, worse grades, traffic accidents, and more. That's why states including California and Florida have mandated later start times. Individual districts across the country — including some in Tennessee — have made the same change. But resistance to later starts is less about the science than it is about logistical and financial difficulties, especially with basics like busing. Melatonin makes people feel drowsy. The brain starts producing it when it gets dark outside, and its production peaks in the middle of the night. Adolescents' brains start releasing melatonin about three hours later than adults' and younger children's brains, according to the American Chemical Society. When teens wake up early, their brains are still producing melatonin. © 2023 npr

Keyword: Biological Rhythms; Sleep
Link ID: 28995 - Posted: 11.11.2023

By Regina G. Barber What your parents didn't tell you about pulling an all-nighter? It might just ease depression for several days. At least, that's what researchers found happened to mice in a study published in the journal Neuron Thursday. Most people who've stayed up all night know the "tired and wired" feeling they get the next day. The body might be exhausted, but the brain feels jittery, hyperactive or even giddy. Even after these changes wear off, sleep loss can have a strong antidepressant effect in people that lasts several days. But researchers hadn't figured out why sleeplessness might have this effect —until this study from neurobiologists at Northwestern University. To study all of this, the team looked at the effects of sleep loss in mice. They induced sleep loss in some of the mice, while the others got a typical night's rest. They found that after this sleepless night, the mice were more excitable, more aggressive, more sexual and less depressed than mice that got a regular amount of sleep. Of course, researchers can't just ask mice whether they feel "less depressed." Instead, they created a depression-like state in all the mice before either disrupting their sleep or allowing them to rest by repeatedly giving them small shocks. In response to these shocks, the mice entered a depressive-like state and eventually stopped trying to escape their cages. Then, they tested the mice's response to shocks again. The ones that had stayed up all night showed a reversed depressive state, indicated by more attempts to escape the shocks. Dopamine is responsible for the brain's reward response. Changes in the brain's dopamine system have also been implicated in conditions like depression and in sleep regulation. And so, to see how the mice's brains responded to their sleepless night, the researchers measured dopamine neuron activity. They saw that sleep-deprived mice showed higher dopamine activity in three regions: the prefrontal cortex, nucleus accumbens and hypothalamus. © 2023 npr

Keyword: Sleep; Depression
Link ID: 28985 - Posted: 11.04.2023

Anil Oza Scientists once considered sleep to be like a shade getting drawn over a window between the brain and the outside world: when the shade is closed, the brain stops reacting to outside stimuli. A study published on 12 October in Nature Neuroscience1 suggests that there might be periods during sleep when that shade is partially open. Depending on what researchers said to them, participants in the study would either smile or frown on cue in certain phases of sleep. “You’re not supposed to be able to do stuff while you sleep,” says Delphine Oudiette, a cognitive scientist at the Paris Brain Institute in France and a co-author of the study. Historically, the definition of sleep is that consciousness of your environment halts, she adds. “It means you don’t react to the external world.” Dream time A few years ago, however, Oudiette began questioning this definition after she and her team conducted an experiment in which they were able to communicate with people who are aware that they are dreaming while they sleep — otherwise known as lucid dreamers. During these people’s dreams, experimenters were able to ask questions and get responses through eye and facial-muscle movements2. Karen Konkoly, who was a co-author on that study and a cognitive scientist at Northwestern University in Evanston, Illinois, says that after that paper came out, “it was a big open question in our minds whether communication would be possible with non-lucid dreamers”. So Oudiette continued with the work. In her latest study, she and her colleagues observed 27 people with narcolepsy — characterized by daytime sleepiness and a high frequency of lucid dreams — and 22 people without the condition. While they were sleeping, participants were repeatedly asked to frown or smile. All of them responded accurately to at least 70% of these prompts. © 2023 Springer Nature Limited

Keyword: Sleep; Learning & Memory
Link ID: 28968 - Posted: 10.25.2023

By Hallie Levine Finding that a good night’s rest has become more elusive over the years? Live well every day with tips and guidance on food, fitness and mental health, delivered to your inbox every Thursday. Older people need about the same amount of sleep as younger ones — generally, seven to eight hours, says Rosanne M. Leipzig, a professor of geriatrics and palliative medicine at the Icahn School of Medicine at Mount Sinai in New York. But about 30 percent of older people get less than seven hours of sleep daily, and almost 20 percent report either frequent insomnia or poor sleep quality, according to a 2022 study published in the journal BMC Public Health. If you have been struggling with sleep, consider the following. How your sleep cycle changes Older adults tend to have less deep (what’s called non-REM) sleep, says Ronald Chervin, chief of the Division of Sleep Medicine at University of Michigan Health in Ann Arbor. So “you may find that you’re woken more by things that would not have disturbed you before,” Leipzig says. You may also notice that you become sleepy earlier in the evening. “As we get older, our circadian rhythm — the body’s internal clock — changes,” Chervin says. This may lead you to head off to sleep earlier at night and wake up earlier in the morning. In addition, at night, older people tend to produce less antidiuretic hormone — which “instructs” the kidneys to cut back on creating fluid — than they once did, Leipzig says. As a result, you may wake up more often at night with the need to urinate. Other medical conditions, such as prostate problems or diabetes, can also contribute to those middle-of-the-night bathroom visits.

Keyword: Sleep
Link ID: 28964 - Posted: 10.17.2023

By Veronique Greenwood This morning, when the sun came up, billions of humans opened their eyes and admitted into their bodies a shaft of light from space. When the stream of photons struck the retina, neurons fired. And in every organ, in nearly every cell, elaborate machinery stirred. Each cell’s circadian clock, a complex of proteins whose levels rise and fall with the sun, clicked into gear. That clock synchronizes our bodies to the light-dark cycle of the planet by controlling the expression of more than 40% of our genome. Genes for immune signals, brain messengers and liver enzymes, to name just a few, are all transcribed to make proteins when the clock says it’s time. That means you are not, biochemically, the same person at 10 p.m. that you are at 10 a.m. It means that evenings are a more dangerous time to take large doses of the painkiller acetaminophen: Liver enzymes that protect against overdose become scarce then. It means that vaccines given in the morning and evening work differently, and that night-shift workers, who chronically disobey their clocks, have higher rates of heart disease and diabetes. People whose clocks run fast or slow are trapped in a hideous state of perpetual jet lag. “We are linked to this day in ways that I think people just push off,” the biochemist Carrie Partch tells me. If we understand the clock better, she has argued, we might be able to reset it. With that information, we might shape the treatment of diseases, from diabetes to cancer. For more than a quarter century, Partch has lived among the orchestrators of the circadian clock, the proteins whose rise and fall control its workings. As a postdoc, she produced the first visualization of the bound pair of proteins at its heart, CLOCK and BMAL1. Since then, she has continued to make visible the whorls and twists of those and other clock proteins while charting how changes to their structure add or subtract time from the day. Her achievements in pursuit of that knowledge have brought her some of the highest honors in this field of science: the Margaret Oakley Dayhoff Award from the Biophysical Society in 2018, and the National Academy of Sciences Award in Molecular Biology in 2022. Simons Foundation All Rights Reserved © 2023

Keyword: Biological Rhythms
Link ID: 28957 - Posted: 10.12.2023

By Stephanie Pappas Your bedmate is whimpering in their sleep and perhaps thrashing about. It looks like a nightmare. Should you wake them? Nope, experts say. As terrible as whatever visions that are running through their head might be, waking someone from a nightmare is more likely to ensure that they’ll remember the bad dream. And if someone appears physically distressed in their sleep like this, it’s more likely that they’re having a night terror than a nightmare; night terrors are different neurological experiences. Nightmares are a normal part of dreaming, says Deirdre Barrett, a dream researcher at Harvard Medical School and author of The Committee of Sleep (Oneiroi Press, 2001). They almost always happen in rapid eye movement (REM) sleep, the stage of sleep marked by brain activity that looks very similar to that of an awake brain. “Except for being scary, they look like every other dream,” Barrett says. During REM sleep, the brain areas responsible for long-term memory storage show altered activation, so people don’t tend to remember their nightmares unless those sleep tales are scary enough to wake them up. Once a dreamer awakens, their long-term memory regions come back on line. Most of the time, someone having a nightmare will be indistinguishable from a peaceful dreamer. During a nightmare, heart rate increases by seven beats per minute on average, says Michael Schredl, a dream and sleep researcher at the Central Institute of Mental Health in Germany. Otherwise the sleeper typically lies still in bed: during REM sleep, muscles are paralyzed, which keeps people from acting out their dreams. If someone is moving around, talking in their sleep or sleepwalking while appearing distressed, it’s more likely a night terror, which occurs during non-REM sleep, Schredl says.

Keyword: Sleep
Link ID: 28946 - Posted: 10.07.2023

By Katherine Harmon Courage On the surface, sleep seems obvious, essential. It comes in long, languid, predictable waves, washing over humans and elephants, birds and fish and beetles. It comes bearing restoration, repair, learning. It follows an ancestral rhythm played deep within our cells, cued by the movement of our planet around our star. Perhaps we could believe this nice, simple fantasy, were it not for an irksome little eyeless fish. More than a decade ago, this fish—the Mexican tetra (Astyanax mexicanus)—caught the eye of a graduate student at New York University. It was not new to science—it had been the subject of fascination for aquarists and researchers for decades, who marveled at its ghostly appearance and the splash of skin where its eyes should have been. But other quirks of the fish turned out to be even more mysterious. In Manhattan, the fish were far from their place of origin: a collection of unassuming caves strung through northeastern Mexico. Inside these caves, it is pitch dark, always cool, quiet, and rather boring. A seemingly perfect place to sleep. So Erik Duboué, the curious graduate student, decided to test if these fish showed any unusual sleep habits. One night in 2009, he made a 2 a.m. visit to the lab and noticed something strange about these sightless fish: They seemed wide awake. On further investigation, he found that despite their soporific native environs, they actually hardly sleep at all. In fact, he discovered, they doze just about three and a half hours out of each 24-hour period. And their bouts of sleep seem to come on entirely randomly and only in brief spurts. Curiously, these eyeless cavefish seem to have been flourishing on this quiescence interruptus for hundreds of thousands of years. “What you have is a fish that is completely healthy—it just doesn’t need to sleep,” says Duboué, who is now a molecular geneticist at Florida Atlantic University. Since then, Duboué and others have been studying the strange sleep of these wakeful creatures—prodding them in the lab to rouse them from their occasional slumber and plumbing their DNA. Combined with investigations into other animals, as well as some peculiar experiments that have sent humans to sleep in caves, scientists are uncovering new, closely guarded truths about sleep that have eluded us in our bright, rhythmic world. © 2023 NautilusNext Inc.

Keyword: Sleep; Evolution
Link ID: 28941 - Posted: 10.03.2023

By Stephanie Pappas If you’ve ever awoken from a vivid dream only to find that you can’t remember the details by the end of breakfast, you’re not alone. People forget most of the dreams they have—though it is possible to train yourself to remember more of them. Dreaming happens mostly (though not always exclusively) during rapid eye movement (REM) sleep. During this sleep stage, brain activity looks similar to that in a waking brain, with some very important differences. Key among them: during REM sleep, the areas of the brain that transfer memories into long-term storage—as well as the long-term storage areas themselves—are relatively deactivated, says Deirdre Barrett, a dream researcher at Harvard Medical School and author of the book The Committee of Sleep (Oneiroi Press, 2001). This may be a side effect of REM’s role in memory consolidation, according to a 2019 study on mice in the journal Science. Short-term memory areas are active during REM sleep, but those only hang on to memories for about 30 seconds. “You have to wake up from REM sleep, generally, to recall a dream,” Barrett says. If, instead, you pass into the next stage of sleep without rousing, that dream will never enter long-term memory. REM sleep occurs about every 90 minutes, and it lengthens as the night drags on. The first REM cycle of the night is typically just a few minutes long, but by the end of an eight-hour night of sleep, a person has typically been in the REM stage for a good 20 minutes, Barrett says. That’s why the strongest correlation between any life circumstance and your memory of dreams is the number of hours you’ve slept. If you sleep only six hours, you’re getting less than half of the dream time of an eight-hour night, she says. Those final hours of sleep are the most important for dreaming. And people tend to remember the last dream of the night—the one just before waking. © 2023 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 28939 - Posted: 10.03.2023

By Meghan Rosen Maybe TikTok showed you people putting a little tape on their lips. Or maybe Instagram served you ads for sticky mouth strips. On social media and beyond, a trend called mouth taping is keeping people’s mouths shut at night — helping them breathe through their nose. Zack Ford, age 38, first tried the trend last month, after recovering from surgery for a deviated septum. Surgery improved his nasal breathing, but at night, he was still sucking air through his lips. In the mornings, Ford says, he’d wake up with a dry mouth and a scratchy throat. Ford brought up mouth taping during an appointment with his doctor, who didn’t think there was harm in trying. That evening, Ford placed a small square of surgical tape over the middle of his lips and settled into bed. It was the best night’s sleep he’s had in recent memory, he says. “When I woke up, I was like, ‘Holy shit this works!’” Mouth taping’s benefits have been touted for everything from the dental to the somnial. People may seal their mouths shut to prevent teeth grinding, bad breath, snoring and sleep apnea — or even to boost fitness or get a stronger jaw. But there’s little data yet to support such claims, dentist Jonathan Quigley wrote in a June 23 letter in the British Dental Journal. Before advising patients, Quigley, who works at a dental clinic in England, would like to see more studies and have a better understanding of the potential risks and benefits. Could taping the mouth improve people’s sleep? Some evidence suggests that mouth taping may have merit for helping treat at least one ailment: sleep apnea. Even here, though, the science is skimpy, and the methods are varied. From a thin strip on the lips to a black patch across the mouth, tape types and techniques can differ between people, brands and studies, making it difficult to draw broad conclusions. © Society for Science & the Public 2000–2023.

Keyword: Sleep
Link ID: 28927 - Posted: 09.27.2023

By Carolyn Wilke Young jumping spiders dangle by a thread through the night, in a box, in a lab. Every so often, their legs curl and their spinnerets twitch — and the retinas of their eyes, visible through their translucent exoskeletons, shift back and forth. “What these spiders are doing seems to be resembling — very closely — REM sleep,” says Daniela Rößler, a behavioral ecologist at the University of Konstanz in Germany. During REM (which stands for rapid eye movement), a sleeping animal’s eyes dart about unpredictably, among other features. In people, REM is when most dreaming happens, particularly the most vivid dreams. Which leads to an intriguing question. If spiders have REM sleep, might dreams also unfold in their poppy-seed-size brains? Rößler and her colleagues reported on the retina-swiveling spiders in 2022. Training cameras on 34 spiders, they found that the creatures had brief REM-like spells about every 17 minutes. The eye-darting behavior was specific to these bouts: It didn’t happen at times in the night when the jumping spiders stirred, stretched, readjusted their silk lines or cleaned themselves with a brush of a leg. Though the spiders are motionless in the run-up to these REM-like bouts, the team hasn’t yet proved that they are sleeping. But if it turns out that they are — and if what looks like REM really is REM — dreaming is a distinct possibility, Rößler says. She finds it easy to imagine that jumping spiders, as highly visual animals, might benefit from dreams as a way to process information they took in during the day. Young jumping spiders have translucent skin. Behind their eyes, tube-shaped retinas move as the spiderlings look about. As shown in this sped-up video, researchers have also observed such retinal tube-shifting behavior in resting — possibly sleeping — spiders. In these intermittent, active bouts, the animals’ legs curl and their spinnerets twitch — suggesting that spiders may experience something like REM sleep. © 2023 Annual Reviews

Keyword: Sleep; Evolution
Link ID: 28896 - Posted: 09.07.2023

By Maria Temming When Christopher Mazurek realizes he’s dreaming, it’s always the small stuff that tips him off. The first time it happened, Mazurek was a freshman at Northwestern University in Evanston, Ill. In the dream, he found himself in a campus dining hall. It was winter, but Mazurek wasn’t wearing his favorite coat. “I realized that, OK, if I don’t have the coat, I must be dreaming,” Mazurek says. That epiphany rocked the dream like an earthquake. “Gravity shifted, and I was flung down a hallway that seemed to go on for miles,” he says. “My left arm disappeared, and then I woke up.” Most people rarely if ever realize that they’re dreaming while it’s happening, what’s known as lucid dreaming. But some enthusiasts have cultivated techniques to become self-aware in their sleep and even wrest some control over their dream selves and settings. Mazurek, 24, says that he’s gotten better at molding his lucid dreams since that first whirlwind experience, sometimes taking them as opportunities to try flying or say hi to deceased family members. Other lucid dreamers have used their personal virtual realities to plumb their subconscious minds for insights or feast on junk food without real-world consequences. But now, scientists have a new job for lucid dreamers: to explore their dreamscapes and report out in real time. Dream research has traditionally relied on reports collected after someone wakes up. But people often wake with only spotty, distorted memories of what they dreamed. The dreamers can’t say exactly when events occurred, and they certainly can’t tailor their dreams to specific scientific studies. © Society for Science & the Public 2000–2023.

Keyword: Sleep; Consciousness
Link ID: 28891 - Posted: 08.30.2023

By Christina Caron About one in four adults in the United States develops symptoms of insomnia each year. In most cases, these are short-lived, caused by things like stress or illness. But one in 10 adults is estimated to have chronic insomnia, which means difficulty falling or staying asleep at least three times a week for three months or longer. Sleep deprivation doesn’t just create physical health problems, it can also harm our minds. A recent poll from the National Sleep Foundation, for example, found a link between poor sleep health and depressive symptoms. In addition, studies have shown that a lack of sleep can lead otherwise healthy people to experience anxiety and distress. Fortunately, there is a well-studied and proven treatment for insomnia that generally works in eight sessions or less: cognitive behavioral therapy for insomnia, or C.B.T.-I. If you cannot find a provider, C.B.T.-I. instruction is easy to access online. Yet it is rarely the first thing people try, said Aric Prather, a sleep researcher at the University of California, San Francisco, who treats patients with insomnia. Instead, they often turn to medication. According to a 2020 survey from the Centers for Disease Control, more than 8 percent of adults reported taking sleep medication every day or most days to help them fall or stay asleep. Studies have found that C.B.T.-I. is as effective as using sleep medications in the short term and more effective in the long term. Clinical trial data suggests that as many as 80 percent of the people who try C.B.T.-I. see improvements in their sleep and most patients find relief in four to eight sessions, even if they have had insomnia for decades, said Philip Gehrman, the director of the Sleep, Neurobiology and Psychopathology lab at the University of Pennsylvania. © 2023 The New York Times Company

Keyword: Sleep
Link ID: 28890 - Posted: 08.30.2023

Nicola Davis Taking a short nap during the day may help to protect the brain’s health as it ages, researchers have suggested after finding that the practice appears to be associated with larger brain volume. While previous research has suggested long naps could be an early symptom of Alzheimer’s disease, other work has revealed that a brief doze can improve people’s ability to learn. Now researchers say they have found evidence to suggest napping may help to protect against brain shrinkage. That is of interest, the team say, as brain shrinkage, a process that occurs with age, is accelerated in people with cognitive problems and neurodegenerative diseases, with some research suggesting this may be related to sleep problems. “In line with these studies, we found an association between habitual daytime napping and larger total brain volume, which could suggest that napping regularly provides some protection against neurodegeneration through compensating for poor sleep,” the researchers note. Writing in the journal Sleep Health, researchers at UCL and the University of the Republic in Uruguay report how they drew on data from the UK Biobank study that has collated genetic, lifestyle and health information from 500,000 people aged 40 to 69 at recruitment. The team used data from 35,080 Biobank participants to look at whether a combination of genetic variants that have previously been associated with self-reported habitual daytime napping are also linked to brain volume, cognition and other aspects of brain health. © 2023 Guardian News & Media Limited

Keyword: Sleep; Development of the Brain
Link ID: 28829 - Posted: 06.21.2023

By Emily Underwood It’s a classic science fiction trope: Astronauts on an interstellar journey are kept in sleek, refrigerated pods in a state of suspended animation. Although such pods remain purely fictional, scientists have pursued research into inducing a hibernation-like state in humans to lessen the damage caused by medical conditions such as heart attacks and stroke, and to reduce the stress and costs of future long-distance space sojourns. In a study published today in Nature Metabolism, scientists report that they can trigger a similar state in mice by targeting part of their brain with pulses of ultrasound. Some experts are calling it a major technical step toward achieving this feat in humans, whereas others say it’s a stretch to extrapolate the results to our species. "It’s an amazing paper,” says Frank van Breukelen, a biologist who studies hibernation at the University of Nevada, Las Vegas and co-authored an editorial accompanying the study. The work builds on a flurry of recent studies that pinpoint specific populations of neurons in a region called the preoptic area (POA) of the hypothalamus. These cells act like an on-off switch for “torpor”—a sluggish, energy-saving state the animals enter when they’re dangerously cold or malnourished. In previous studies, scientists genetically engineered these neurons to respond to light or certain chemicals, and found they could cause mice to enter a torpid state even when they were warm and well-fed. Such invasive techniques can’t be easily translated to people, however, Breukelen notes. “That’s really not going to happen in people.” The new ultrasound study, led by bioengineer Hong Chen and her team at Washington University in St. Louis required no genetic engineering. Chen knew from previous research that some neurons have specialized pores called TRPM2 ion channels that change shape in response to ultrasonic waves, including the subset of POA cells that controls mouse torpor. To see what effect that had on the animals’ behavior, her team next glued miniature, speakerlike devices on the heads of mice to focus these waves on the POA.

Keyword: Sleep; Brain imaging
Link ID: 28800 - Posted: 05.27.2023