Links for Keyword: Sleep

Follow us on Facebook or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 1100

By Jackie Rocheleau After experimenting on a hen, his dog, his goldfish, and himself, dentist William Morton was ready. On Oct. 16, 1846, he hurried to the Massachusetts General Hospital surgical theater for what would be the first successful public test of a general anesthetic. His concoction of sulfuric ether and oil from an orange (just for the fragrance) knocked a young man unconscious while a surgeon cut a tumor from his neck. To the onlooking students and clinicians, it was like a miracle. Some alchemical reaction between the ether and the man’s brain allowed him to slip into a state akin to light sleep, to undergo what should have been a painful surgery with little discomfort, and then to return to himself with only a hazy memory of the experience. General anesthesia redefined surgery and medicine, but over a century later it still carries significant risks. Too much sedation can lead to neurocognitive disorders and may even shorten lifespan; too little can lead to traumatic and painful wakefulness during surgery. So far, scientists have learned that, generally speaking, anesthetic drugs render people unconscious by altering how parts of the brain communicate. But they still don’t fully understand why. Although anesthesia works primarily on the brain, anesthesiologists do not regularly monitor the brain when they put patients under. And it is only in the past decade that neuroscientists interested in altered states of consciousness have begun taking advantage of anesthesia as a research tool. “It’s the central irony” of anesthesiology, says George Mashour, a University of Michigan neuroanesthesiologist, whose work entails keeping patients unconscious during neurosurgery and providing appropriate pain management. Mashour is one of a small set of clinicians and scientists trying to change that. They are increasingly bringing the tools of neuroscience into the operating room to track the brain activity of patients, and testing out anesthesia on healthy study participants. These pioneers aim to learn how to more safely anesthetize their patients, tailoring the dose to individual patients and adjusting during surgery. They also want to better understand what governs the transitions between states of consciousness and even hope to crack the code of coma. © 2022 NautilusThink Inc, All rights reserved.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 4: Development of the Brain
Link ID: 28480 - Posted: 09.17.2022

Michael Heithaus Could you explain how fish sleep? Do they drift away on currents, or do they anchor themselves to a particular location when they sleep? – Laure and Neeraj, New York From the goldfish in your aquarium to a bass in a lake to the sharks in the sea – 35,000 species of fish are alive today, more than 3 trillion of them. All over the world, they swim in hot springs, rivers, ponds and puddles. They glide through freshwater and saltwater. They survive in the shallows and in the darkest depths of the ocean, more than five miles down. If those trillions of fish, three major types exist: bony fish, like trout and sardines; jawless fish, like the slimy hagfish; and sharks and rays, which are boneless – instead, they have skeletons made of firm yet flexible tissue called cartilage. And all of them, every last one, needs to rest. Whether you’re a human or a haddock, sleep is essential. It gives a body time to repair itself, and a brain a chance to reset and declutter. As a marine biologist, I’ve always wondered how fish can rest. After all, in any body of water, predators are all over the place, lurking around, ready to eat them. But somehow they manage, like virtually all creatures on Earth. See the mysterious spot off the coast of Mexico where sharks take a nap. How they do it Scientists are still learning about how fish sleep. What we do know: Their sleep is not like ours. © 2010–2022, The Conversation US, Inc.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28465 - Posted: 09.07.2022

By Rebecca Sohn Distinctive bursts of sleeping-brain activity, known as sleep spindles, have long been generally associated with strengthening recently formed memories. But new research has managed to link such surges to specific acts of learning while awake. These electrical flurries, which can be observed as sharp spikes on an electroencephalogram (EEG), tend to happen in early sleep stages when brain activity is otherwise low. A study published in Current Biology shows that sleep spindles appear prominently in particular brain areas that had been active in study participants earlier, while they were awake and learning an assigned task. Stronger spindles in these areas correlated with better recall after sleep. “We were able to link, within [each] participant, exactly the brain areas used for learning to spindle activity during sleep,” says University of Oxford cognitive neuroscientist Bernhard Staresina, senior author on the study. Staresina, Marit Petzka of the University of Birmingham in England and their colleagues devised a set of tasks they called the “memory arena,” which required each participant to memorize a sequence of images appearing inside a circle. While the subjects did so, researchers measured their brain activity with an EEG, which uses electrodes placed on the head. Participants then took a two-hour nap, after which they memorized a new image set—but then had to re-create the original image sequence learned before sleeping. During naps, the researchers recorded stronger sleep spindles in the specific brain areas that had been active during the pre-sleep-memorization task, and these areas differed for each participant. This suggested that the spindle pattern was not “hardwired” in default parts of the human brain; rather it was tied to an individual's thought patterns. The researchers also observed that participants who experienced stronger sleep spindles in brain areas used during memorization did a better job re-creating the images' positions after the nap. © 2022 Scientific American

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory and Learning
Link ID: 28460 - Posted: 09.03.2022

Steven Strogatz Dreams are so personal, subjective and fleeting, they might seem impossible to study directly and with scientific objectivity. But in recent decades, laboratories around the world have developed sophisticated techniques for getting into the minds of people while they are dreaming. In the process, they are learning more about why we need these strange nightly experiences and how our brains generate them. In this episode, Steven Strogatz speaks with sleep researcher Antonio Zadra of the University of Montreal about how new experimental methods have changed our understanding of dreams. Steven Strogatz (00:03): I’m Steve Strogatz, and this is The Joy of Why, a podcast from Quanta Magazine that takes you into some of the biggest unanswered questions in math and science today. (00:13) In this episode, we’re going to be talking about dreams. What are dreams exactly? What purpose do they serve? And why are they often so bizarre? We’ve all had this experience: You’re dreaming about something fantastical, some kind of crazy story with a narrative arc that didn’t actually happen, with people we don’t necessarily know, in places we may have never even been. Is this just the brain trying to make sense of random neural firing? Or is there some evolutionary reason for dreaming? Dreams are inherently hard to study. Even with all the advances in science and technology, we still haven’t really found a way to record what someone else is dreaming about. Plus, as we all know, it’s easy to forget our dreams as soon as we wake up, unless we’re really careful to write them down. But even with all these difficulties, little by little, dream researchers are making progress in figuring out how we dream and why we dream. (01:11) Joining me now to discuss all this is Dr. Antonio Zadra, a professor at the University of Montreal and a researcher at the Center for Advanced Research in Sleep Medicine. His specialties include the study of nightmares, recurrent dreams and lucid dreaming. He’s also the coauthor of the recent book When Brains Dream, exploring the science and mystery of sleep. Tony, thank you so much for joining us today. Strogatz (01:39): I’m very excited to talk to you about this. So let’s start with thinking about the science of dreams as you and your colleagues see it today. Why are dreams so hard to study? All Rights Reserved © 2022

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28454 - Posted: 08.27.2022

Yuta Senzai Massimo Scanziani Does rapid eye movement during sleep reveal where you’re looking at in the scenery of dreams, or are they simply the result of random jerks of our eye muscles? Since the discovery of REM sleep in the early 1950s, the significance of these rapid eye movements has intrigued and fascinated scores of scientists, psychologists and philosophers. REM sleep, as the name implies, is a period of sleep when your eyes move under your closed eyelids. It’s also the period when you experience vivid dreams. We are researchers who study how the brain processes sensory information during wakefulness and sleep. In our recently published study, we found that the eye movements you make while you sleep may reflect where you’re looking in your dreams. Past studies have attempted to address this question by monitoring the eye movements of people as they slept and waking them up to ask what they were dreaming. The goal was to find a possible connection between the content of a dream just before waking up (say, a car coming in from the left) and the direction the eyes moved at that moment. Unfortunately, these studies have led to contradictory results. It could be that some participants inaccurately reported dreams, and it’s technically difficult to match a given eye movement to a specific moment in a self-reported dream. We decided to bypass the problem of dream self-reporting. Instead, we used a more objective way to measure dreams: the electrical activity of a sleeping mouse brain. Mice, like humans and many other animals, also experience REM sleep. Additionally, they have a sort of internal compass in their brains that gives them a sense of head direction. When the mouse is awake and running around, the electrical activity of this internal compass precisely reports its head direction, or “heading,” as it moves in its environment. © 2010–2022, The Conversation US, Inc.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 7: Vision: From Eye to Brain
Link ID: 28453 - Posted: 08.27.2022

By Sujata Gupta Lack of sleep has been linked to heart disease, poor mood and loneliness (SN: 11/15/16). Being tired could also make us less generous, researchers report August 23 in PLOS Biology. The hour of sleep lost in the switch over to Daylight Savings Time every spring appears to reduce people’s tendency to help others, the researchers found in one of three experiments testing the link between sleep loss and generosity. Specifically, they showed that average donations to one U.S.-based nonprofit organization dropped by around 10 percent in the workweek after the time switch compared with four weeks before and after the change. In Arizona and Hawaii, states that do not observe Daylight Savings Time, donations remained unchanged. With over half of the people living in parts of the developed world reporting that they rarely get enough sleep during the workweek, the finding has implications beyond the week we spring forward, the researchers say. “Lack of sleep shapes the social experiences we have [and] the kinds of societies we live in,” says neuroscientist Eti Ben Simon of the University of California, Berkeley. To test the link between sleep loss and generosity, Ben Simon and her team first brought 23 young adults into the lab for two nights. The participants slept through one night and stayed awake for another night. In the mornings, participants completed a standardized altruism questionnaire rating their likelihood of helping strangers or acquaintances in various scenarios. For instance, participants rated on a scale from 1 to 5, with 1 for least likely to help and 5 for most likely, whether they would give up their seat on a bus to a stranger or offer a ride to a coworker in need. Participants never read the same scenario more than once. Roughly 80 percent of participants showed less likelihood of helping others when sleep-deprived than when rested. © Society for Science & the Public 2000–2022.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 11: Emotions, Aggression, and Stress
Link ID: 28444 - Posted: 08.24.2022

By Carolyn Wilke Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. By day, jumping spiders hunt their prey, stalking and pouncing like cats. When the lights go down, these pea-sized predators hang out — and maybe their minds spin dreams. As they twitch their legs and move their eyes, Evarcha arcuata, a species of jumping spiders, show something reminiscent of rapid eye movement, or R.E.M., sleep, researchers report Monday in the Proceedings of the National Academy of Sciences. R.E.M. is the phase of sleep during which most human dreaming occurs. The study suggests that R.E.M. sleep may be more common than realized across animals, which may help untangle the mysteries of its purpose and evolution. To “look at R.E.M. sleep in something as distantly related to us as spiders is just utterly fascinating,” said Lauren Sumner-Rooney, a sensory biologist at the Leibniz Institute for Biodiversity and Evolution Research who wasn’t part of the new study. Daniela Roessler, a behavioral ecologist at the University of Konstanz in Germany and one of the study’s authors, was surprised when she noticed that jumping spiders sometimes dangle upside down during the night. Dr. Roessler started filming the resting arachnids and noticed other odd behaviors. “All of a sudden, they would make these crazy movements with the legs and start twitching. And it just reminded me immediately of a sleeping — not to say dreaming — cat or dog,” said Dr. Roessler. Such jerky movements in limbs are a marker of R.E.M. sleep, a state in which most of the body’s muscles go slack and the brain’s electrical activity mimics being awake. And then there’s the darting eyes, from which R.E.M. gets its name. But that’s tricky to spot it in animals with eyes that do not move, including spiders. However, part of a jumping spider’s eye does move. The acrobatic arachnids have eight eyes in total, and behind the lenses of their two biggest eyes are light-catching retinas that move to scan the environment. The arthropods’ exterior typically obscures these banana-shaped tubes, except when the spiders are babies and have translucent exoskeletons. So Dr. Roessler’s team looked for flitting retinas during rest in spiderlings younger than 10 days old. “It’s really clever,” said Paul Shaw, a neuroscientist at the Washington University School of Medicine. The researchers chose the right animal for this question, he added. © 2022 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28431 - Posted: 08.11.2022

Mo Costandi We spend approximately one-third of our lives sleeping, but why sleep is important is a big unanswered question, one which science has only begun to answer recently. We now know, for example, that the brain cleans itself while we sleep, and that long-term memories form during the rapid eye movement (REM) stage of sleep. Your brain is highly active during sleep Sleep can be defined as a temporary state of unconsciousness, during which our responses to the outside world are reduced. Yet, we also know that the brain is active during sleep, and there is growing evidence that it remains highly responsive: For instance, your sleeping brain will respond to your name, categorize words and then prepare appropriate actions, and even learn new information. Now, a new study by researchers at UCLA and Tel Aviv University shows that the human brain remains highly responsive to sound during sleep, but it does not receive feedback from higher order areas — sort of like an orchestra with “the conductor missing.” The findings could point to a better understanding of the extent to which the brain processes information in disorders of consciousness such as coma and vegetative states, and to the neural mechanisms of conscious awareness. The missing conductor Hanna Hayat and her colleagues had the rare opportunity to record the activity of cells directly from the brains of 13 patients with drug-resistant epilepsy, who were being evaluated for brain surgery and gave written consent to participate in the study during the evaluation. The researchers implanted depth electrodes in multiple regions of the patients’ brains, primarily to identify the source of their seizures, so that the abnormal tissue could be surgically removed. Over the course of eight overnight sessions and six daytime naps, they played various sounds — including words, sentences and music — to the patients through bedside loudspeakers. They also used standard electroencephalogram (EEG) to monitor the patients’ sleep stages and recorded their sleep behavior with video. © Copyright 2007-2022 & BIG THINK,

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28416 - Posted: 08.03.2022

By Linda Searing Routinely getting a good night’s sleep has been added to the American Heart Association’s list of key components of cardiovascular health, lengthening the list to eight factors the association believes can lead to a longer, higher-quality life without heart disease. Heart disease is the leading cause of death in the United States and has been for the past century, according to the Centers for Disease Control and Prevention. Since 2010, the AHA had focused on seven points: maintaining a healthy weight, not smoking, being physically active, eating a healthy diet, and keeping blood pressure, cholesterol and blood sugar at acceptable levels. Now, however, as indicated in its report published in the journal Circulation, the AHA believes that healthy sleep also should be taken into account. The group’s suggested goal is seven to nine hours of sleep daily for adults, and more for children (eight to 10 hours for 13- to 18-year-olds, nine to 12 hours for 6- to 12-year-olds and 10 to 16 hours for children 5 and younger). Sleep has long been considered vital to good health, both physically and psychologically. Sleep gives the body a needed break to heal and repair itself, setting people up to function normally when they awaken. But a lack of sleep (or poor-quality sleep) puts a person at higher risk for such conditions as diabetes, obesity, high blood pressure and more. © 1996-2022 The Washington Post

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28395 - Posted: 07.14.2022

By Lisa L. Lewis To any observers, the electrodes were the most visible sign that the Stanford Summer Sleep Camp was a bit out of the ordinary. Joe Oliveira, one of the original campers, recalls that right after check-in, four electrodes were glued to his hair, two taped next to his eyes, and several more by his chin. The electrodes remained in place the whole time. Long cords came out of them that were, “very small, like an iPhone charger,” he told me. During the day, the cords were often tied back and taped together into a compact bundle at the back of his head. The “trodes” (as the campers were called because of their electrode ponytails) attracted their fair share of weird looks on their outings around the university campus. And there was something else peculiar: Like clockwork, every two hours, they all returned to the dorm for “nap tests,” according to Mary Carskadon, who was pursuing her doctorate in neuro- and biobehavioral sciences at Stanford University. In their darkened dorm rooms, all the campers — a mix of kids and teens — would lie quietly for 20 minutes and attempt to fall asleep. Meanwhile, technicians in a nearby control room monitored their brainwaves, eye movements, and chin-muscle activity being transmitted from their electrodes via the cords, which had been plugged into a box near the headboard that had cables linked to a polysomnograph machine in the other room. There, a continuous paper trail issued forth mapping the campers’ data. When the time was up, the campers were roused and unplugged. The counselors recorded their vital signs, then plugged their wires into a second box closer to the dorm room desk and ran the campers through a short series of tests to measure their recall, attention span, and other aspects of alertness and cognitive functioning. Tom Harvey, who worked as a counselor/technician at the camp for several years, recalled a mix of “math tests and memory tests and ‘can you suffer through boredom’ tests.”

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory and Learning
Link ID: 28381 - Posted: 06.25.2022

By Oliver Whang The sleep debt collectors are coming. They want you to know that there is no such thing as forgiveness, only a shifting expectation of how and when you’re going to pay them back. You think of them as you lie in bed at night. How much will they ask for? Are you solvent? You fall asleep, then wake up in a cold sweat an hour later. You fall asleep, then wake up, drifting in and out of consciousness until morning. As most every human has discovered, a couple nights of bad sleep is often followed by grogginess, difficulty concentrating, irritability, mood swings and sleepiness. For years, it was thought that these effects, accompanied by cognitive impairments like lousy performances on short-term memory tests, could be primarily attributed to a chemical called adenosine, a neurotransmitter that inhibits electrical impulses in the brain. Spikes of adenosine had been consistently observed in sleep-deprived rats and humans. Adenosine levels can be quickly righted after a few nights of good sleep, however. This gave rise to a scientific consensus that sleep debt could be forgiven with a couple of quality snoozes — as reflected in casual statements like “I’ll catch up on sleep” or “I’ll be more awake tomorrow.” But a review article published recently in the journal Trends in Neurosciences contends that the folk concept of sleep as something that can be saved up and paid off is bunk. The review, which canvassed the last couple of decades of research on long term neural effects of sleep deprivation in both animals and humans, points to mounting evidence that getting too little sleep most likely leads to long-lasting brain damage and increased risk of neurodegenerative disorders like Alzheimer’s disease. © 2022 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28380 - Posted: 06.25.2022

By Anna Gibbs Turns out there is rest for the wicked: Sleepy mosquitoes are more likely to catch up on missed z’s than drink blood, a new study finds. Most people are familiar with the aftermath of a poor night’s sleep. Insects also suffer; for instance, drowsy honeybees struggle to perform their signature waggle dance, and weary fruit flies show signs of memory loss. In the case of sleep-deprived mosquitoes, they give up valuable time for feeding in favor of sleeping overtime, researchers report June 1 in Journal of Experimental Biology. The preference for dozing over dining is surprising given that “we know that mosquitoes love blood a lot,” says Oluwaseun Ajayi, a disease ecologist at the University of Cincinnati. Scientists have long been interested in mosquitoes’ circadian rhythms, the internal clock that determines their sleep and awake times (SN: 10/2/17). Knowing when a mosquito is awake — and biting — is important for understanding and limiting disease transmission. For instance, malaria, often transmitted by nocturnal mosquitoes, is kept under control by slinging netting around beds. But new research suggests that mosquitoes that feed during the day may also spread the disease. It’s challenging to study sleeping bloodsuckers in the lab. That’s partly because awake mosquitoes are aroused by the presence of a meal — the experimenter. And when mosquitoes do fall asleep, they look rather similar to peers that are merely resting to conserve energy. © Society for Science & the Public 2000–2022.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28359 - Posted: 06.09.2022

By Peter Kendall As he gets ready for sleep each night, Don Tucker slips on an electrode cap and checks a little computer on his bedside table. Many workers at the private lab, run by the professor emeritus at the University of Oregon, follow the same routine. The experimental device monitors the nightly voyage through sleep. After sensing light sleep for a few minutes, it pulses electric current through the scalp and skull, nudging the brain into that nirvana known as deep sleep. The goal is not just a more restful slumber. Groundbreaking discoveries made in the past decade have revealed that the brain has a power-washing system that switches into high gear during deep sleep, flushing away harmful waste. This nightly cleanup is part of the restorative power of sleep and revives concentration, memory and motor skills. As we age, however, this cleansing system gets sloppier, and it can begin to leave behind some of the metabolic detritus of the day, including the amyloid beta proteins found in the plaque that characterize Alzheimer’s disease and other devastating neurological disorders. The controversial approval of an Alzheimer’s drug reignites the battle over the underlying cause of the disease The stunning revelation in 2012 of this previously unknown brain infrastructure — dubbed the glymphatic system — has ushered in a new age of research and invention not only about sleep but also aging, dementia and brain injury. Nearly 300 research papers were published last year on the glymphatic system. © 1996-2022 The Washington Post

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28346 - Posted: 06.01.2022

If you’ve ever been put under anaesthesia, you might recall the disorienting feeling of blinking your eyes one moment and the next, waking up hours later. Now, findings from a new study illustrate just how profoundly general anaesthesia alters the state of the brain as it induces and maintains unconsciousness. It’s the first paper to track travelling brain waves in subjects all the way through the process of losing to regaining consciousness. An interdisciplinary team has found that the commonly used anaesthetic, propofol, substantially alters how different frequencies of brain waves travel along the cortex – the surface of the brain – and the research has been published in the Journal of Cognitive Neuroscience. Unconsciousness induced by propofol may be in part due to an increase in the strength and direction of slow delta traveling brain waves that disrupt higher-frequency waves associated with cognition. “The rhythms that we associate with higher cognition are drastically altered by propofol,” explains senior author Earl Miller, professor of neuroscience with the Department of Brain and Cognitive Sciences at the Massachusetts Institute of Technology (MIT) in the US. “The beta traveling waves seen during wakefulness are pushed aside, redirected by delta traveling waves that have been altered and made more powerful by the anaesthetic,” he says. “The deltas come through like a bull in a china shop.” Conscious brains show a mixture of brain waves of different frequencies, which rotate or travel straight in various directions: you could think of them like the numerous waves on a choppy ocean.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28314 - Posted: 05.04.2022

By Elizabeth Preston On dry nights, the San hunter-gatherers of Namibia often sleep under the stars. They have no electric lights or new Netflix releases keeping them awake. Yet when they rise in the morning, they haven’t gotten any more hours of sleep than a typical Western city-dweller who stayed up doom-scrolling on their smartphone. Research has shown that people in non-industrial societies — the closest thing to the kind of setting our species evolved in — average less than seven hours a night, says evolutionary anthropologist David Samson at the University of Toronto Mississauga. That’s a surprising number when you consider our closest animal relatives. Humans sleep less than any ape, monkey or lemur that scientists have studied. Chimps sleep around 9.5 hours out of every 24. Cotton-top tamarins sleep around 13. Three-striped night monkeys are technically nocturnal, though really, they’re hardly ever awake — they sleep for 17 hours a day. Samson calls this discrepancy the human sleep paradox. “How is this possible, that we’re sleeping the least out of any primate?” he says. Sleep is known to be important for our memory, immune function and other aspects of health. A predictive model of primate sleep based on factors such as body mass, brain size and diet concluded that humans ought to sleep about 9.5 hours out of every 24, not seven. “Something weird is going on,” Samson says. Research by Samson and others in primates and non-industrial human populations has revealed the various ways that human sleep is unusual. We spend fewer hours asleep than our nearest relatives, and more of our night in the phase of sleep known as rapid eye movement, or REM. The reasons for our strange sleep habits are still up for debate but can likely be found in the story of how we became human. Graph shows average time spent sleep of different primate species. Humans sleep the least at seven hours per night; the three-striped night monkey sleeps the most at nearly 17 hours. © 2022 Annual Reviews

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28310 - Posted: 04.30.2022

By Michele Lent Hirsch Sleep problems are a hallmark of modern American life — perhaps never more so than recently. In 2016, the Centers for Disease Control and Prevention found that a third of Americans were getting too little sleep at night. But then came the stressors of the pandemic, job losses, disrupted schedules and closed schools, which kept record numbers of Americans up at night or unable to wake up in the morning. As many as 2 in 3 Americans reported getting either too much or too little sleep, in a survey from the American Psychological Association during the pandemic’s second year. And the insomnia of the past two years may be stubbornly hanging on: Many people continue having more trouble falling asleep or staying asleep or have seen unusual shifts in their sleep schedules. All of this is taking a toll. “These different types of sleep changes seem to be closely related to [problems with] mental health,” says Karianne Dion, a graduate student in clinical psychology at the University of Ottawa. Research she co-wrote, published in the Journal of Sleep Research in 2021, found “worse symptoms of stress, anxiety, and depression” among those who are sleeping less or going to bed later and waking up later than before. Researchers have long known that anxiety and depression can lead to sleeplessness, while sleeping poorly can increase the likelihood of anxiety and depression. But a good night’s rest is also critical for a strong immune system, as well as for health overall. Insufficient sleep over time is associated with a greater risk of diabetes, high blood pressure and heart disease, according to the CDC. It can lead to memory and cognitive issues as well. So how can we get the sleep we need? Here’s how to solve seven common problems that can interfere with your rest and your health. © 1996-2022 The Washington Post

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28303 - Posted: 04.27.2022

Kayt Sukel Each night, as you transition into deep sleep from wakefulness, your body undergoes a remarkable transformation. Your muscles relax. Your breathing slows. Your temperature and blood pressure drop. Even your brain activity changes, decelerating into slow, coordinated waves. Despite these remarkable physiological changes, scientists are now learning that the brain is far from idle during sleep. Rather, it remains hard at work, facilitating memory and learning while uncoupled from the external world. “For a long time, we believed that being awake all day depleted you and that sleep was what was required to restore and reinvigorate the whole body, including the brain,” says Robert Stickgold, a pioneering sleep researcher at Harvard Medical School. “It turns out that rest has very little to do with the function of sleep—rather, our brain is sorting and consolidating the information we learned during the day so we can better access it when it’s needed.” Anyone who has ever pulled an all-nighter knows the effect that sleep deprivation can have on cognitive function, including one’s ability to learn and retain new information. Yet, over the last few decades, neuroscientists across the globe have learned that sleep plays an integral role in memory—and it is a role that is highly conserved across the animal kingdom. To better understand how sleep helps us remember, these researchers have been working to characterize not only the physiological changes observed during sleep, but also the neural mechanisms underlying them. Nearly every animal on earth, from fruit flies to non-human primates, experiences some form of sleep, a naturally recurring state of altered consciousness and inhibited sensory activity. And while the exact amount of time spent in slumber, and the patterns of neural activity, differ from animal to animal, humans are no different. We need sleep to thrive. © 2022 The Dana Foundation.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory and Learning
Link ID: 28285 - Posted: 04.16.2022

By Erin Blakemore From the streetlights outside our bedrooms to the lamps and devices inside, sleeping with some amount of light has become a way of life for many. That may not be such a bright idea. Research suggests that sleeping in a moderately lit room could affect metabolic and cardiovascular health compared with snoozing in a room with dimmer light. We don’t need more sleep. We just need more darkness. In a study published in PNAS, researchers at Northwestern University had two groups of 10 young adults sleep in differently lit rooms. One group slept in rooms with dim light for two nights; the other slept one night in a room with dim night and the next in a room with moderate overhead light — about the equivalent of an overcast day. Participants wore heart monitors at night. In the morning, they did a variety of glucose tests. Both groups got the same amount of sleep but their bodies experienced very different nights. Both groups responded well to insulin the first night, when they both slept in dim lighting. On the second night, however, the group sleeping in brighter lighting didn’t respond as well to insulin. The dim light sleepers’ insulin resistance scores fell about 4 percent on the second night, while the bright sleepers’ rose about 15 percent. Their heart rates were faster on the bright night, too. The heightened heart rate and other measures led the researchers to conclude that light activates the sympathetic nervous system, which usually dominates bodily functions during the day.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28252 - Posted: 03.26.2022

By Veronique Greenwood Sharks are celebrated for their apparently ceaseless motion — a small handful of species such as great white sharks must even swim to breathe, keeping water washing over their gills. Still, all that moving doesn’t preclude sharks from having a rest. Sleep across the animal kingdom manifests itself in many peculiar ways, like the birds whose brains sleep one half at a time or the bats that spend almost every hour of their day snoozing. And in a paper published in Current Biology on Wednesday, researchers confirmed that the draughtsboard shark, a small nocturnal shark native to New Zealand, appears to be sleeping during periods of calm, reporting that their metabolism and posture change significantly during these bouts of repose. They do, however, in a creepy touch, keep their eyes open for a lot of it. Further research will be required to demonstrate that other kinds of sharks catch underwater z’s like the draughtsboard shark. But the new study supports the hypothesis that one reason organisms might have evolved sleep is as a tool for conserving energy. Draughtsboard sharks were identified last year as sleepers by this same group of researchers based in New Zealand and Australia. They watched captured sharks carefully in tanks and tested their responses to disturbances during their restful periods. (These sharks are not among those that swim to breathe; they hang out on the ocean floor and pump water over their gills.) The team found that it was more difficult to prompt the sharks into movement if they had been still for a long time, suggesting they were in fact sleeping. This time, said Craig Radford, a professor of marine science at the University of Auckland and an author of the new paper, the researchers were looking to compare the sharks’ metabolisms during these periods of calm, defined as being still for longer than five minutes, with when they were resting for shorter periods and when they were actively swimming. They used a specially built tank with instruments that let them monitor how much oxygen the sharks were using, a way to indirectly measure metabolism. Seven sharks each spent 24 hours in the tank, and the researchers found that these states were indeed quite different. © 2022 The New York Times Company

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28234 - Posted: 03.11.2022

ByKelly Servick In 1997, Laura Gould put her 15-month-old daughter, Maria, down for a nap and returned to find her unresponsive. She had died suddenly, with no clues to explain the tragedy besides a fever the night before. When her daughter’s body was sent to the medical examiner’s office, “I thought they’d call me in an hour and tell me what happened … like on TV,” Gould says. Months later, neither that office nor independent pathologists had an explanation. “I hated ending it with ‘the autopsy was inconclusive, go on and live your life now,’” she says. “It just didn’t really feel like that was an option.” Gould co-founded a nonprofit foundation to support grieving parents, raise research funds, and increase awareness of sudden unexplained death in childhood (SUDC), a term used for children older than 12 months. In the United States, roughly 400 deaths fall into this category each year—about one-quarter as many as are labeled sudden infant death syndrome (SIDS). Two recent genetic analyses, one funded in part by Gould’s SUDC Foundation, now suggest potential causes for at least a small fraction of cases: mutations in genes associated with epilepsy, heart arrhythmias, and neurodevelopmental disorders. “Having this data is important,” says Marco Hefti, a neuropathologist at the University of Iowa Carver College of Medicine who was not involved in the new studies. SUDC is not a single disease, but “a grab bag of different things—and the more of those different things you can pull out, the better for everybody.” Neither study can say with certainty that a mutation is responsible for a child’s death. But the findings provide a basis for animal studies that could reveal how the genetic changes interfere with vital functions. They might also inform future child death investigations and potentially even screening programs to prevent deaths. Research on SUDC has lagged that on the more common and better known SIDS. Yet, biologically, SIDS and SUDC “may be part of a spectrum,” says Ingrid Holm, a medical geneticist at Boston Children’s Hospital. In both, death often occurs during sleep, and researchers suspect contributors including undetected heart defects, metabolic disorders, and central nervous system abnormalities. The children who die are roughly 10 times more likely than the average child to have a history of febrile seizures—convulsions that come with fevers in young children, notes neurologist Orrin Devinsky of New York University (NYU) Langone Health. © 2022 American Association for the Advancement of Science.

Related chapters from BN: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 28200 - Posted: 02.12.2022