By Elizabeth Pennisi Dive among the kelp forests of the Southern California coast and you may spot orange puffball sponges (Tethya californiana)—creatures that look like the miniature pumpkins used for pies. No researchers paid them much mind until 2017, when William Joiner, a neuroscientist at the University of California (UC), San Diego, decided to look into whether sponges take naps. That’s not as silly a question as it seems. Over the past few years, studies in worms, jellyfish, and hydra have challenged the long-standing idea that sleep is unique to creatures with brains. Now, “The real frontier is finding an animal that sleeps that doesn’t have neurons at all,” says David Raizen, a neurologist at the University of Pennsylvania (UPenn) Perelman School of Medicine. Sponges, some of the earliest animals to appear on Earth, fit that description. To catch one snoozing could upend researchers’ definition of sleep and their understanding of its purpose. Scientists have often defined sleep as temporary loss of consciousness, orchestrated by the brain and for the brain’s benefit. That makes studying sleep in brainless creatures controversial. “I do not believe that many of these organisms sleep—at least not the way you and I do,” says John Hogenesch, a genome biologist at Cincinnati Children’s Hospital Medical Center. Calling the restful, unresponsive state seen in jellyfish and hydra “sleeplike” is more acceptable to him. But others in the field are pushing for a much more inclusive view: that sleep evolved not with modern vertebrates as previously assumed, but perhaps a half-billion years ago when the first animals appeared. “I think if it’s alive, it sleeps,” says Paul Shaw, a neuroscientist from Washington University in St. Louis. The earliest life forms were unresponsive until they evolved ways to react to their environment, he suggests, and sleep is a return to the default state. “I think we didn’t evolve sleep, we evolved wakefulness.” © 2021 American Association for the Advancement of Science.

Keyword: Sleep; Evolution
Link ID: 28061 - Posted: 11.03.2021

By Brooke Jarvis Deirdre Barrett’s body was in bed, but her mind was in a library. The library was inside a very old house, with glowing oil lamps and shelves of beautiful leatherbound books. At first it felt snug and secure and timeless, exactly the sort of place an academic like Barrett, who teaches in the psychiatry department at Harvard Medical School and edits the scientific journal Dreaming, might find inviting. But as the dream went on, she remembered later, “I became less able to focus on the library and more overwhelmed by the unseen horror outside.” Beyond the windows of the softly lit library, “a terrible plague was ravaging the world.” When Barrett woke up, it was mid-March of 2020. She had been reading about the novel coronavirus in Wuhan since it began to make headlines, and she wondered, as she often did when she read about events in the news, how this one might be showing up in the dreams of the people who were experiencing it: residents on lockdown in China, overwhelmed doctors and nurses in Italy. The dreamlife of collective catastrophe was something she had studied repeatedly during her academic career — analyzing, for example, the dreams of Kuwaitis after the Iraqi invasion and those of British officers held prisoner by the Nazis during World War II, to see how the dreams compared with one another and with dreams from calmer times. As a child, Barrett was fascinated by her own dreams, which were often vivid. They tended to stay with her well after she woke up, making nights feel like a time for slipping in and out of new worlds and adventures, often ones she’d read about but was now able to interact with and inhabit fully. When she grew up, she decided, she would become a writer of fiction; many of the early stories she wrote were set not just in worlds that she imagined, but also in and out of the various dream worlds of her characters. She was deeply curious about the dream lives of other people: When she started writing for her high school newspaper, she occasionally asked her sources if they’d had dreams related to whatever she was interviewing them about. Dreams were a window, albeit a very strange one, into the way that other people and their minds worked. In college Barrett decided that fiction was not her future (though she did develop a practice of making visual art about what she saw and felt while sleeping). What she wanted was to be a scientist who studied what happened inside dreams. © 2021 The New York Times Company

Keyword: Sleep
Link ID: 28060 - Posted: 11.03.2021

A new study re-emphasises the fact that oversleeping can be harmful for us – and especially for older people Says who? Says Brendan P Lucey, MD. Who? Associate professor of neurology and director of the Washington University Sleep Medicine Center. And lead author of a new study at Washington University School of Medicine (which is neither in Washington DC nor Washington state but St Louis, Missouri, confusingly). Here we go, a new study: what does it say? That it is, in fact, possible to have too much of a good thing. And if that good thing is sleep, how much is too much? Possibly anything over seven and a half hours a night. What?! What about my beauty sleep? Eight hours, absolute minimum. The study monitored 100 older adults, in their mid to late 70s. I am awake now, so tell me what they found. That there’s an association between less than five and a half hours’ sleep and, more surprisingly, more than seven and a half hours’ sleep and reduced cognitive performance for older adults. So how much is right for the over-75s? The “sweet spot” is somewhere in the middle range, between five and a half and seven and a half hours’ kip. What else is associated with cognitive decline in older people? Alzheimer’s is the main cause, contributing to around 70% of dementia cases. “It’s been challenging to determine how sleep and different stages of Alzheimer’s disease are related,” said Lucey. “But that’s what you need to know to start designing interventions.” © 2021 Guardian News & Media Limited

Keyword: Sleep
Link ID: 28056 - Posted: 10.30.2021

Infants who sleep longer through the night and with fewer interruptions may be less likely to become overweight during their first six months of life, according to a study published in the journal SLEEP(link is external). While the research only showed a link – not a cause-effect relationship – between infants’ sleep and weight, the findings suggest that newborns can reap some of the same health benefits that others get from consistent, quality shut-eye. The research emerged from the Rise and SHINE (Sleep Health in Infancy & Early Childhood) study, which analyzes ways sleep may influence a newborn’s growth and development. The five-year study is being supported in part by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. “What is particularly interesting about this research is that the sleep-obesity association we see across the lifespan appears in infancy and may be predictive of future health outcomes,” said Marishka K. Brown, Ph.D., director of the National Center on Sleep Disorders Research, located within the NHLBI. Brown noted that multiple studies have shown links between good sleep and improved health. For children, this includes a reduced risk of developing obesity and diabetes, while supporting development, learning, and behavior. In the current study, researchers observed 298 newborns and found that for every hourly increase in nighttime sleep, measured between 7 p.m. and 8 a.m., the infants were 26% less likely to become overweight. Likewise, for each reduction in nighttime awakening, they were 16% less likely to become overweight.

Keyword: Sleep; Obesity
Link ID: 28047 - Posted: 10.23.2021

By Christina Caron For about 1 in 20 people in the northern half of the United States, cooling temperatures and shorter, darker days may signal the onset of seasonal affective disorder, or SAD, a type of depression that typically arrives in the fall or winter, then goes away in the spring. Unlike mild cases of the “winter blues,” SAD symptoms make it difficult to function. It tends to start with so-called “vegetative symptoms”: an increased appetite and a craving for carbohydrates like french fries or ice cream, the urge to sleep longer hours, difficulty getting up in the morning and feeling wiped out at work. Then, in three to four weeks, “the mood plummets,” said Michael Terman, a professor of clinical psychology at Columbia University and an expert in seasonal affective disorder. Patients with SAD develop major depression, which includes persistent feelings of sadness, withdrawal from friends and family and a loss of interest in activities that were once enjoyable. Researchers don’t yet know why some people develop SAD and others do not, but the disorder is believed to run in families and is more common among women. SAD develops in the fall and winter because shorter daylight hours and less sunlight shift the body’s internal clock, and certain mood-regulating hormones, like serotonin, oscillate with the seasons. The good news is that because SAD is tied to the changing seasons, “you can predict its onset and ward it off,” Dr. Terman said. If you have already started experiencing vegetative symptoms — for example you are sleeping longer and having more difficulty waking up — or if you already know you are susceptible to seasonal affective disorder, experts said it’s best to start implementing preventive measures before major depression sets in. © 2021 The New York Times Company

Keyword: Depression; Biological Rhythms
Link ID: 28018 - Posted: 10.02.2021

Annie Melchor After finishing his PhD in neuroscience in 2016, Thomas Andrillon spent a year road-tripping around Africa and South America with his wife. One evening, on a particularly difficult road in Patagonia, his mind began to wander and he ended up accidentally flipping the car. Luckily, no one was hurt. As locals rushed in to help, they asked Andrillon what had happened. Was there an animal on the road? Had he fallen asleep at the wheel? “I had difficulty explaining that I was just thinking about something else,” he remembers. This experience made him think. What had happened? What was going on in his brain when his mind began to wander? In 2017, Andrillon started his postdoctoral research with neuroscientists Naotsugu Tsuchiya and Joel Pearson at Monash University in Melbourne. Shortly after, Tsuchiya and Andrillon teamed up with philosopher Jennifer Windt, also at Monash, to dive into the neural basis of mind wandering. Initially, Andrillon says, they wanted to know if they could detect mind wandering from facial expressions, recalling how teachers claim to be very good at knowing when their students are not paying attention. So they did a pilot experiment in which they filmed their test subjects performing a tedious, repetitive task. After reviewing the videos, one of Andrillon’s students came to him, concerned. “I think we have a problem,” said the student. “[The subjects] look exhausted.” Sure enough, even though all the study participants were awake, they were obviously struggling to not fall asleep, says Andrillon. It was this observation that gave them the idea to broaden their focus, and start looking at the connection between wavering attention and sleep. © 1986–2021 The Scientist.=

Keyword: Attention; Sleep
Link ID: 28016 - Posted: 10.02.2021

By Leigh Weingus I’ve struggled with sleep since I was a teenager, and have spent almost as long trying to fix it. I’ve absorbed countless books and articles on getting better sleep that instructed me to go blue-light free at least two hours before bedtime, take nightly baths to lower my body temperature, keep my phone far from my bedroom and avoid caffeine after 12 p.m. In between all my diligent sleep hygiene work, I couldn’t help but feel like there was a larger force at play. My sleep seemed to change throughout my menstrual cycle, for example, getting worse in the days before my period and significantly better afterward. When I was pregnant, I experienced the best sleep of my life, and when I stopped breastfeeding, I didn’t sleep for days. I finally started to ask myself: When we talk about getting better sleep, why aren’t we talking more about hormones? According to the National Sleep Foundation, the lifetime risk of insomnia is 40 percent higher for women than it is for men. Blaming this discrepancy entirely on hormones oversimplifies it — women also tend to take on the bulk of household worrying and emotional labor, and they tend to experience higher levels of anxiety. But according to Mary Jane Minkin, an obstetrician-gynecologist and clinical professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale School of Medicine, anecdotal evidence and studies suggest that hormones likely play a role.

Keyword: Sleep; Hormones & Behavior
Link ID: 28000 - Posted: 09.22.2021

By Sarah Lyall In the winter of 1995, the Brazilian neuroscientist Sidarta Ribeiro moved to New York to pursue his Ph.D. at Rockefeller University. His arrival, he writes in his fascinating, discursive new book, “The Oracle of Night,” precipitated one of the strangest periods of his life. Overcome by a sudden, inexplicable lassitude, Ribeiro did little but attend classes, read and sleep. But his sleep was exciting and revelatory, full of vivid, evocative dreams that enriched his waking hours. “I began to dream in English,” he writes, “and my dreams became even more intense, with representations of epic narratives through unnaturally deserted New York streets on the sunny, icy morning of an endless Sunday.” This period lasted for several months and then abruptly ended. When Ribeiro re-entered the world, as if emerging from hibernation, he was refreshed and alert, energized by a “cognitive transformation” that he felt had been enhanced by his dreaming imagination. He became fascinated by dreams — why do we have them, what do they say about us, what role do they play in our lives? — and embarked on a lifetime of study of this most interesting of topics. (He wears many hats. He got his Ph.D. in animal behavior; he is the founder and vice director of the Brain Institute at the Federal University of Rio Grande do Norte in Brazil.) “The Oracle of Night” makes a resounding case for the mystery, beauty and cognitive importance of dreams. Ribeiro marshals prodigious evidence to bolster his case that a dream is not simply “fragments of memory assembled at random” (as he summarizes Francis Crick’s dismissive position), but instead is a “privileged moment for prospecting the unconscious” — a phenomenon that, in Carl Jung’s words, “prepares the dreamer for the events of the following day.” © 2021 The New York Times Company

Keyword: Sleep
Link ID: 27979 - Posted: 09.08.2021

Rachel Hall Napping has long been a symbol of laziness, but actually it is an essential bodily function that improves our memory, creativity, empathy and problem-solving abilities. Sleep scientists say the gold standard for good physical and mental health is making sure you get between seven and nine hours’ sleep every day, but not necessarily all in one go. “Capitalists in the old days told us that we should do 12 to 16 hours of work for them, and then have eight hours to do what we like, so they wanted us to sleep efficiently in a certain window – that’s where the idea of consolidated sleep comes from,” said Till Roenneberg, a professor of chronobiology at the University of Munich. He has been studying civilisations without electricity, and has observed that people often woke up during the night, took a break and went back to sleep. However, Matthew Walker, a professor of neuroscience at the University of California, Berkeley, and author of Why We Sleep, said people who have trouble falling asleep at night should approach naps with caution, and that everyone should avoid napping after 3pm. “If you nap too late in the day it’s a bit like snacking before main meal, it just takes the edge off your sleep hunger at night,” he said. The ideal length, according to the scientists, is 20 to 25 minutes. Any longer and you’ll fall into a deeper sleep cycle, which lasts for about 90 minutes. This means when you wake up you will experience “sleep inertia”, or grogginess. © 2021 Guardian News & Media Limited

Keyword: Sleep; Biological Rhythms
Link ID: 27965 - Posted: 08.28.2021

By Jillian Kramer Mice are at their best at night. But a new analysis suggests researchers often test the nocturnal creatures during the day—which could alter results and create variability across studies—if they record time-of-day information at all. Of the 200 papers examined in the new study, more than half either failed to report the timing of behavioral testing or did so ambiguously. Only 20 percent reported nighttime testing. The analysis was published in Neuroscience & Biobehavioral Reviews. West Virginia University neuroscientist Randy Nelson, the study's lead author, says this is likely a matter of human convenience. “It is easier to get students and techs to work during the day than [at] night,” Nelson says. But that convenience comes at a cost. “Time of day not only impacts the intensity of many variables, including locomotor activity, aggressive behavior, and plasma hormone levels,” but changes in those variables can only be observed during certain parts of the diurnal cycle, says University of Wyoming behavioral neuroscientist William D. Todd. This means that “failing to report time of day of data collection and tests makes interpretation of results extremely difficult,” adds Beth Israel Deaconess Medical Center staff scientist Natalia Machado. Neither Todd nor Machado was involved in the new study. The study researchers say it is critical that scientists report the timing of their work and consider the fact that animals' behavioral and physiological responses can vary with the hour. As a first step, Nelson says, “taking care of time-of-day considerations seems like low-hanging fruit in terms of increasing behavioral neuroscience research reliability, reproducibility and rigor.” © 2021 Scientific American

Keyword: Biological Rhythms
Link ID: 27953 - Posted: 08.21.2021

By Virginia Hughes In the 1960s, the drug was given to women during childbirth to dampen their consciousness. In the 1990s, an illicit version made headlines as a “date rape” drug, linked to dozens of deaths and sexual assaults. And for the last two decades, a pharmaceutical-grade slurry of gamma-hydroxybutyrate, or GHB, has been tightly regulated as a treatment for narcolepsy, a disorder known for its sudden sleep attacks. Now, the Food and Drug Administration has approved the drug for a new use: treating “idiopathic hypersomnia,” a mysterious condition in which people sleep nine or more hours a day, yet never feel rested. Branded as Xywav, the medication is thought to work by giving some patients restorative sleep at night, allowing their brains to be more alert when they wake up. It is the first approved treatment for the illness. But some experts say the publicly available evidence to support the new approval is weak. And they worry about the dangers of the medication, which acts so swiftly that its label advises users to take it while in bed. Xywav and an older, high-salt version called Xyrem have a host of serious side effects, including breathing problems, anxiety, depression, sleepwalking, hallucinations and suicidal thoughts. GHB “has serious safety concerns, both in terms of its abuse liability and its addictive potential,” said Dr. Lewis S. Nelson, the director of medical toxicology at Rutgers New Jersey Medical School. An estimated 40,000 people in the United States have been diagnosed with idiopathic hypersomnia, but Dr. Nelson said that many more people with daytime drowsiness might wind up with this diagnosis now that it has an F.D.A.-approved treatment. The disorder’s hallmark symptoms — sleep cravings, long naps and brain fog — overlap with many other conditions. The more people who take the drug, the more opportunity for abuse. “The potential for the scope of use to expand is very real,” Dr. Nelson said. “So that is concerning to me.” © 2021 The New York Times Company

Keyword: Sleep; Drug Abuse
Link ID: 27947 - Posted: 08.14.2021

By Katharine Q. Seelye Dr. J. Allan Hobson, a psychiatrist and pioneering sleep researcher who disputed Freud’s view that dreams held hidden psychological meaning, died on July 7 at his home in East Burke, Vt. He was 88. The cause was kidney failure resulting from diabetes, said his daughter, Julia Hobson Haggerty. For some time, sleep was not taken seriously as an academic pursuit. Even Dr. Hobson, who was a professor of psychiatry at Harvard Medical School and director of the Laboratory of Neurophysiology at the Massachusetts Mental Health Center, joked that the only known function of sleep was to cure sleepiness. But over a career that spanned more than four decades, his own research and that of others showed that sleep is crucial to normal cognitive and emotional function, including learning and memory. In more than 20 books — among them “The Dreaming Brain” (1988); “Dreaming as Delirium: How the Brain Goes Out of its Mind” (1999), and “Dream Self” (2021), a memoir — he popularized his research and that of others, including the findings that sleep begins in utero and is essential for tissue growth and repair throughout life. “He showed that sleep isn’t a nothing state,” Ralph Lydic, who conducted research with Dr. Hobson in the 1980s and is a professor of neuroscience at the University of Tennessee, said in a phone interview. “He demonstrated that the brain is as active during R.E.M. sleep as it is during wakefulness,” he added, referring to sleep characterized by rapid eye movement. “We know as much about sleep as we do in part because of him.” One of his most influential contributions to dream research came in 1977, when Dr. Hobson and a colleague, Robert McCarley, produced a cellular and mathematical model that they believed showed how dreams occur. Dreams, they said, are not mysterious codes sent by the subconscious but rather the brain’s attempt to attribute meaning to random firings of neurons in the brain. © 2021 The New York Times Company

Keyword: Sleep
Link ID: 27929 - Posted: 08.04.2021

By Laura Sanders A brush with death led Hans Berger to invent a machine that could eavesdrop on the brain. In 1893, when he was 19, Berger fell off his horse during maneuvers training with the German military and was nearly trampled. On that same day, his sister, far away, got a bad feeling about Hans. She talked her father into sending a telegram asking if everything was all right. To young Berger, this eerie timing was no coincidence: It was a case of “spontaneous telepathy,” he later wrote. Hans was convinced that he had transmitted his thoughts of mortal fear to his sister — somehow. So he decided to study psychiatry, beginning a quest to uncover how thoughts could travel between people. Chasing after a scientific basis for telepathy was a dead end, of course. But in the attempt, Berger ended up making a key contribution to modern medicine and science: He invented the electroencephalogram, or EEG, a device that could read the brain’s electrical activity. Berger’s machine, first used successfully in 1924, produced a readout of squiggles that represented the electricity created by collections of firing nerve cells in the brain. © Society for Science & the Public 2000–2021.

Keyword: Sleep
Link ID: 27895 - Posted: 07.08.2021

By Katherine Ellison Remember the line from that old folk song? If living were a thing that money could buy You know the rich would live and the poor would die. Sadly, there’s little “if” about it. On average, the poor live less healthy lives and are more than three times as likely to die prematurely as the rich. That’s true for many well-documented reasons, including less healthy diets with too much processed food, polluted neighborhoods and a lot more toxic stress. In recent years, however, researchers have added one more factor to this mix: It turns out that the poor, as well as socially disadvantaged racial minorities, sleep much less well on average than the rich, which can take a major toll on their physical and mental health. “We used to think that sleep problems were limited to Type A professionals, and they certainly aren’t immune, but low-income individuals and racial minorities are actually at greatest risk,” says Wendy Troxel, a senior behavioral and social scientist at the RAND Corporation, who coauthored an analysis of socioeconomic disparities in sleep and health in the 2020 Annual Review of Public Health. Inadequate sleep among low-income adults and racial minorities contributes to higher rates of illnesses, including cardiovascular disease and dementia, both of which are more common among these groups, Troxel and her coauthors point out. One study they cite attributes more than half of the differences in health outcomes between whites and Blacks, for example, to differences in quantity or quality of sleep. You might think of this as the great sleep divide. © 2021 Annual Reviews, Inc

Keyword: Sleep; Stress
Link ID: 27881 - Posted: 06.29.2021

By Nicholas Bakalar If you are a morning person, you may be at reduced risk for major depression, a new study suggests. Several studies of the body’s circadian sleep-wake cycle have shown that being an early bird is associated with a lower risk for depression. But those studies were observational so could not prove cause and effect. For example, people who are early birds may have other health or lifestyle behaviors that reduce their risk for depression — they may have a healthier diet, for example, exercise more, or have fewer health conditions, such as chronic pain, that are associated with depression. All these factors, and many others, could explain the decreased risk for depression, and not the fact of being an early bird. Moreover, depression itself causes sleep disturbances, so it could be that depression is a cause of being a night owl, rather than the other way around. The new study, however, offers more compelling evidence that going to bed early and waking early may, in itself, provide protection against depression, independent of other factors. The study, published in JAMA Psychiatry, uses a research method called Mendelian randomization that helps pinpoint the cause of what may be a cause-and-effect relationship. With Mendelian randomization, researchers can compare large groups of people based on genetic variants that are independent of other health or behavioral characteristics — in this case, the tendency to being a night owl or a morning person, inherited traits that are randomly allocated during our development in the womb. More than 340 genetic variants associated with circadian sleep rhythm have been identified, and the researchers can compare large groups of people with the genetic variants for being a morning person with groups that lack them. Nature has, in essence, set up the randomized experiment for them. © 2021 The New York Times Company

Keyword: Biological Rhythms; Depression
Link ID: 27868 - Posted: 06.23.2021

By Anahad O'Connor According to recent studies, the number of people complaining of insomnia skyrocketed during the pandemic, rising from 20 percent of adults last summer to nearly 60 percent in March. If you’re one of those people who’s been plagued by poor sleep, the Well desk is here to help. Recently, we asked our readers to tell us two things: What’s keeping you from getting a good night’s rest? And what are the most pressing questions you would ask a sleep expert? More than 1,200 of you responded. You asked about insomnia, supplements, middle-of-the-night awakenings, snoring bed mates and more. So we collected your most popular questions, brought them to the world’s top sleep experts and shared their answers below. Sometimes I am physically tired but can’t fall asleep. How is that possible? This is what’s known as the tired but wired syndrome. Usually, it’s driven by stress and anxiety. Even if you’re exhausted, a racing mind can activate the “fight or flight” branch of your nervous system, making you alert and unable to fall asleep. “For us to fall asleep and stay asleep, we need to go in the opposite nervous system direction,” said Matthew Walker, a professor of neuroscience and psychology at the University of California, Berkeley, and the author of the best-selling book “Why We Sleep.” “We need to shift over to the calming branch of the nervous system called the parasympathetic nervous system.” © 2021 The New York Times Company

Keyword: Sleep
Link ID: 27847 - Posted: 06.11.2021

Nicholas Bakalar Many people wear a CPAP machine at night to treat the interrupted breathing of obstructive sleep apnea, a condition that affects an estimated 22 million Americans. But CPAP machines can be noisy, cumbersome and uncomfortable, and many people stop using the devices altogether, which can have dire long-term consequences. Mouth guards may be a more comfortable and easy-to-use alternative for many people with obstructive sleep apnea, according to a new report. The study, published in Laryngoscope, looked at 347 people with sleep apnea who were fitted with a mouth guard by an otolaryngologist. Two-thirds of patients reported they were comfortable wearing the devices, and the devices appeared to be effective in helping to relieve the disordered breathing of obstructive sleep apnea. The lead author of the study, Dr. Guillaume Buiret, head of otolaryngology at Valence Hospital in Valence, France, said that if he had sleep apnea, he would choose an oral appliance first. “It’s easy to tolerate, effective and it costs a lot less than CPAP,” he said. “Thirty to 40 percent of our patients can’t use CPAP, and these patients almost always find the dental appliance helpful. I would recommend it as a first-line treatment” Loud snoring may be the most obvious consequence of sleep apnea, but the condition, if left untreated, can lead to a broad range of complications, including high blood pressure, heart disease, liver dysfunction and Type 2 diabetes. © 2021 The New York Times Company

Keyword: Sleep
Link ID: 27838 - Posted: 06.02.2021

Abby Olena Leptin is a hormone released by fat cells in adult organisms, and researchers have largely focused on how it controls appetite. In a study published May 18 in Science Signaling, the authors show that leptin promotes synapse formation, or synaptogenesis, in developing rodent neurons in culture. “This paper does a really wonderful job [breaking] down the mechanisms” of leptin signaling, and the authors look at changes in synaptic function, not just at the protein level, but also on a physiological level, says Laura Cocas, a neuroscientist at Santa Clara University who was not involved in the study. “Because all of the work on the paper is done in vitro, they can do very careful analysis . . . to break down each step in the signaling pathway.” When Washington State University neuroscientist Gary Wayman and his group started working on leptin about 10 years ago, most of the research had examined the hormone’s function in regulating satiety. But “we and others knew that leptin surged during a critical period of neuronal—and in particular synaptic—development in the brain,” he says. In people, this surge happens during the third trimester of fetal development and, in rodents, over the first few weeks of life. “This surge in leptin is independent of the amount of adipose tissue that’s present. And it does not control feeding during this period because feeding circuits have not developed, so we really wanted to understand what the developmental role was.” Wayman and colleagues focused on the hippocampus because, despite being one of the best-characterized regions in the brain, there wasn’t a lot of information out there about what the leptin receptors present were doing—particularly during development. Multiple groups had also shown that leptin injected in this brain region can improve cognition and act as an antidepressant. © 1986–2021 The Scientist.

Keyword: Obesity; Learning & Memory
Link ID: 27837 - Posted: 05.29.2021

Veronique Greenwood The hydra is a simple creature. Less than half an inch long, its tubular body has a foot at one end and a mouth at the other. The foot clings to a surface underwater — a plant or a rock, perhaps — and the mouth, ringed with tentacles, ensnares passing water fleas. It does not have a brain, or even much of a nervous system. And yet, new research shows, it sleeps. Studies by a team in South Korea and Japan showed that the hydra periodically drops into a rest state that meets the essential criteria for sleep. On the face of it, that might seem improbable. For more than a century, researchers who study sleep have looked for its purpose and structure in the brain. They have explored sleep’s connections to memory and learning. They have numbered the neural circuits that push us down into oblivious slumber and pull us back out of it. They have recorded the telltale changes in brain waves that mark our passage through different stages of sleep and tried to understand what drives them. Mountains of research and people’s daily experience attest to human sleep’s connection to the brain. But a counterpoint to this brain-centric view of sleep has emerged. Researchers have noticed that molecules produced by muscles and some other tissues outside the nervous system can regulate sleep. Sleep affects metabolism pervasively in the body, suggesting that its influence is not exclusively neurological. And a body of work that’s been growing quietly but consistently for decades has shown that simple organisms with less and less brain spend significant time doing something that looks a lot like sleep. Sometimes their behavior has been pigeonholed as only “sleeplike,” but as more details are uncovered, it has become less and less clear why that distinction is necessary. All Rights Reserved © 2021

Keyword: Sleep; Evolution
Link ID: 27825 - Posted: 05.19.2021

By Sofia Moutinho There’s no 9-to-5 for female northern elephant seals. After the winter breeding season, the animals spend more than 19 hours—and up to 24 hours—per day hunting in the northern Pacific Ocean, killing up to 2000 small fish daily to survive, according to a new study of these elusive animals. The work, made possible by cameras and devices attached to the seals’ heads, could also help scientists monitor other deep-ocean life. “This study is fascinating,” says Jeremy Goldbogen, a marine biologist at Stanford University who was not part of the research. “The advanced technology provides unprecedented levels of detail on where and when the elephant seals forage in a deep, dark ocean.” Northern elephant seals (Mirounga angustirostris) are mysterious animals. They appear onshore, on some Pacific Coast beaches, only twice a year: in late December or early January to mate or give birth, and about 2 months later to shed their fur. They spend the rest of their time, almost 10 months, fishing. Males, which can weigh up to 2 tons—about the weight of a small truck—hunt big fish close to the coast. Females, which are only about one-third of the size, hunt smaller fish in a deep-sea region known as the twilight zone. To get food from the zone, which reaches depths of 1500 meters, the females must hold their breath for up to 1.5 hours. “The physiological challenges that these animals face to meet their daily energetic demand is an extraordinary feat,” Goldbogen says. To find out how the females survive on the small fish—some of which are just 2 centimeters long—Japanese and U.S. researchers attached infrared video cameras with depth sensors to the heads of 48 female elephant seals. They also attached GPS trackers and a special device that could count every time a seal opened its mouth. (The researchers called their device the Kami Kami Logger, after the Japanese sound for biting, similar to the English “chomp chomp.”) © 2021 American Association for the Advancement of Science

Keyword: Sleep
Link ID: 27819 - Posted: 05.15.2021