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Ian Sample Science editor For Jules Verne it was the friend who keeps us waiting. For Edgar Allan Poe so many little slices of death. But though the reason we spend a third of our lives asleep has so far resisted scientific explanation, research into the impact of sleepless nights on brain function has shed fresh light on the mystery - and also offered intriguing clues to potential treatments for depression. In a study published on Tuesday, researchers show for the first time that sleep resets the steady build-up of connectivity in the human brain which takes place in our waking hours. The process appears to be crucial for our brains to remember and learn so we can adapt to the world around us. The loss of a single night’s sleep was enough to block the brain’s natural reset mechanism, the scientists found. Deprived of rest, the brain’s neurons seemingly became over-connected and so muddled with electrical activity that new memories could not be properly laid down. Lack of sleep alters brain chemicals to bring on cannabis-style 'munchies' But Christoph Nissen, a psychiatrist who led the study at the University of Freiburg, is also excited about the potential for helping people with mental health disorders. One radical treatment for major depression is therapeutic sleep deprivation, which Nissen believes works through changing the patient’s brain connectivity. The new research offers a deeper understanding of the phenomenon which could be adapted to produce more practical treatments. © 2016 Guardian News and Media Limited

Related chapters from BP7e: 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, Learning, and Development
Link ID: 22593 - Posted: 08.24.2016

by Laura Sanders When someone uses the phrase “sleeping like a baby,” it’s obvious that they don’t really know how babies sleep. Many babies, especially newborns, are lousy sleepers, waking up every few hours to rustle around, cry and eat. For creatures who sleep up to 18 hours per 24-hour period, newborns are exhausting. That means that bone-tired parents are often desperate to get their babies to sleep so they can rest too. A study published in the September Pediatrics captured this nightly struggle in the homes of 162 Pennsylvanian families. And the results revealed something disturbing: Despite knowing that they were being videotaped, many parents didn’t put their babies into a safe sleeping spot. The risk of sleep-related infant deaths, including those caused by strangulation or sudden infant death syndrome, goes up when babies are put in unsafe sleeping positions or near suffocation hazards. Babies should be on their back on a firm mattress free of any objects. But that wasn’t the case for the majority of babies in the study, says Ian Paul, a pediatrician at Penn State. As a parent to three, Paul is sympathetic to the difficulties of soothing babies to sleep. “The first few months are really exhausting,” he says. But as a pediatrician, he also sees the risks of ignoring safe sleep guidelines. “Parents need to realize that these risks are real and might happen to them.” The videos taken for the study revealed that at 1 month of age, nearly all of the babies were put onto a sleep surface that had a loose or ill-advised item. |© Society for Science & the Public 2000 - 2016

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22592 - Posted: 08.24.2016

By Roni Caryn Rabin We’ve all heard about the power of positive thinking. But will it help me sleep? My problem isn’t falling asleep – it’s staying asleep. This particular form of torture has been dubbed “sleep-maintenance” insomnia. Call me a high-functioning sufferer: I’m usually O.K. once I’ve had my morning coffee. But I worry about the long-term health ramifications of losing sleep. Now several medical organizations have endorsed a treatment known as cognitive behavioral therapy for insomnia or C.B.T.-I. In May the American College of Physicians advised its members that C.B.T.-I. was the first treatment they should offer patients with insomnia. I wanted to try it, but there is a shortage of trained therapists with expertise in C.B.T.-I. I didn’t want to wait for an appointment; I just wanted to solve the problem. So I decided to try an online sleep program. Convincing data that internet-based programs are effective is piling up, and a recent review of clinical trials reported that insomniacs improved their sleep as much after online C.B.T.-I. programs as they did after face-to-face C.B.T.-I. counseling. Internet programs are likely to be cheaper than most therapists, too. I downloaded a five-week course called Conquering Insomnia for $40. Another online C.B.T. program called SHUTi charges $135 for 16 weeks of access to a program, which includes a series of six sessions and follow-up for 10 weeks. Both programs provide individualized feedback on your weekly sleep logs. The developers of these programs say they want them to be accessible to as many people as possible. One in 10 people suffer from insomnia. “The number of clinicians nationally who know how to do C.B.T. for insomnia is a couple of thousand. We need 100,000,” said Dr. Gregg Jacobs, a sleep medicine specialist and assistant professor of psychiatry at the University of Massachusetts Medical School who developed the Conquering Insomnia program. “There are tens of millions of people out there who have insomnia.” © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22591 - Posted: 08.24.2016

By Andrea Anderson When we bed down in a new locale, our sleep often suffers. A recent study finds that this so-called first-night effect may be the result of partial wakefulness in one side of the brain—as if the brain is keeping watch. Researchers at Brown University and the Georgia Institute of Technology used neuroimaging and a brain wave–tracking approach called polysomnography to record activity in four brain networks in 11 individuals as they slept on two nights about a week apart. The subjects nodded off at their normal bedtimes, and their brain was scanned for about two hours—the length of a sleep cycle. As participants slept, right hemisphere regions showed consistent slow-wave activity regardless of the night. Yet average slow-wave activity was shallower in their left hemisphere during the first night—an asymmetry that was enhanced in those who took longer to fall asleep. The results, published in May in Current Biology, suggest systems in one side of the brain remain active as people venture into unfamiliar sleep situations—an apparent survival strategy reminiscent of the unihemispheric sleep reported in certain animals. Because the results represent just one sleep cycle, however, it is unclear whether the left side of the brain is always tasked with maintaining attentiveness, explains the study's senior author Yuka Sasaki, a cognitive, linguistic and psychological sciences researcher at Brown. It is possible the right hemisphere takes over guard dog duties at some point in the night. © 2016 Scientific American

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22580 - Posted: 08.22.2016

By Melinda Wenner Moyer The science of sleep is woefully incomplete, not least because research on the topic has long ignored half of the population. For decades, sleep studies mostly enrolled men. Now, as sleep researchers are making a more concerted effort to study women, they are uncovering important differences between the sexes. Hormones are a major factor. Estrogen, progesterone and testosterone can influence the chemical systems in the brain that regulate sleep and arousal. Moreover, recent studies indicate that during times of hormonal change—such as puberty, pregnancy and menopause—women are at an increased risk for sleep disorders such as obstructive sleep apnea, restless legs syndrome and insomnia. Women also tend to report that they have more trouble sleeping before and during their menstrual periods. And when women do sleep poorly, they may have a harder time focusing than sleep-deprived men do. In one recent study, researchers shifted the sleep-wake cycles of 16 men and 18 women for 10 days. Volunteers were put on a 28-hour daily cycle involving nearly 19 hours of awake time followed by a little more than nine hours of sleep. During the sleep-shifted period, the women in the group performed much less accurately than the men on cognitive tests. The findings, published in April of this year in the Proceedings of the National Academy of Sciences USA, may help explain why women are more likely than men to get injured working graveyard shifts. In addition, a study conducted in 2015 in teenagers reported that weekday sleep deprivation affects cognitive ability more in girls than in boys. © 2016 Scientific American

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 22568 - Posted: 08.18.2016

By Karen Weintraub There’s been lots of coverage lately about meeting exercise recommendations by completing small chunks of exercise throughout the day rather than one, continuous session. Does the same hold true for meeting sleep recommendations? No. Unfortunately, sleep does not work that way. Substituting periodic naps for one consolidated night of sleep creates severe sleep deprivation, said Dr. Daniel Buysse, a sleep expert and professor of psychiatry at the University of Pittsburgh. He and his colleagues once did an experiment in which volunteers agreed to alternate 30 minutes of sleep with 60 minutes of wakefulness for two and a half days straight. They ended up sleep deprived, he said, because sound sleep is not equally likely at all times of day. People have a better chance of falling quickly into deep, restful sleep at night than midday, even if they feel as though they could fall asleep at any time. “Our biological clocks do not allow us to sleep as well during the day as at night,” he said. “All sleep is not necessarily equal.” That’s why night workers get less sleep on average than people who work other shifts – and suffer health consequences as a result, he said. But it’s always a good idea to make up for lost sleep, regardless of the time of day, said Dr. Ruth Benca, a professor of psychiatry and director of the Center for Sleep Medicine and Sleep Research at the University of Wisconsin-Madison. People used to think that it was better to pull an all-nighter than to break it up with a short nap, but that isn’t true, she said. On the other hand, it may be helpful, she said, to take an afternoon nap to compensate for a short night of sleep, bringing a six-and-a-half hour night up to seven, for instance. “If you have to stay awake for a prolonged period, you can mitigate that a little bit by taking some naps, but you can’t live your life like that,” Dr. Benca said. “Any sleep is better than no sleep, and more sleep is better than less sleep.” © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22567 - Posted: 08.18.2016

Rachel Ehrenberg Pulling consecutive all-nighters makes some brain areas groggier than others. Regions involved with problem solving and concentration become especially sluggish when sleep-deprived, a new study using brain scans reveals. Other areas keep ticking along, appearing to be less affected by a mounting sleep debt. The results might lead to a better understanding of the rhythmic nature of symptoms in certain psychiatric or neurodegenerative disorders, says study coauthor Derk-Jan Dijk. People with dementia, for instance, can be afflicted with “sundowning,” which worsens their symptoms at the end of the day. More broadly, the findings, published August 12 in Science, document the brain’s response to too little shut-eye. “We’ve shown what shift workers already know,” says Dijk, of the University of Surrey in England. “Being awake at 6 a.m. after a night of no sleep, it isn’t easy. But what wasn’t known was the remarkably different response of these brain areas.” The research reveals the differing effects of the two major factors that influence when you conk out: the body’s roughly 24-hour circadian clock, which helps keep you awake in the daytime and put you to sleep when it’s dark, and the body’s drive to sleep, which steadily increases the longer you’re awake. Dijk and collaborators at the University of Liege in Belgium assessed the cognitive function of 33 young adults who went without sleep for 42 hours. Over the course of this sleepless period, the participants performed some simple tasks testing reaction time and memory. The sleepy subjects also underwent 12 brain scans during their ordeal and another scan after 12 hours of recovery sleep. Throughout the study, the researchers also measured participants’ levels of the sleep hormone melatonin, which served as a way to track the hands on their master circadian clocks. |© Society for Science & the Public 2000 - 2016

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22548 - Posted: 08.12.2016

By Alice Klein Rise and shine! Neuronal switches have been discovered that can suddenly rouse flies from slumber – or send them into a doze. There are several parallels between sleep in flies and mammals, making fruit flies a good choice for investigating how we sleep. One way to do this is to use optogenetics to activate specific neurons to see what they do. This works by using light to turn on cells genetically modified to respond to certain wavelengths. Gero Miesenböck at the University of Oxford and his team have discovered how to wake flies up. Using light as the trigger the team stimulated neurons that release a molecule called dopamine. The dopamine then switched off sleep-promoting neurons in what’s called the dorsal fan-shaped body, waking the flies. Meanwhile, Fang Guo at Brandeis University in Waltham, Massachusetts, and his team have found that activating neurons that form part of a fly’s internal clock will send it to sleep. When stimulated, these neurons released glutamate, which turned off activity-promoting neurons in the master pacemaker area of the brain. While human and fly brains are obviously very different in structure, being asleep or awake are similar states regardless of the kind of brain an animal has, says Bruno van Swinderen at the University of Queensland, Australia. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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: 22517 - Posted: 08.04.2016

By Sarah Kaplan Sleep just doesn't make sense. "Think about it," said Gero Miesenböck, a neuroscientist at the University of Oxford. "We do it. Every animal with a brain does it. But obviously it has considerable risks." Sleeping animals are incredibly vulnerable to attacks, with no obvious benefit to make up for it — at best, they waste precious hours that could be used finding food or seducing a mate; at worst, they could get eaten. "If evolution had managed to invent an animal that doesn’t need to sleep ... the selective advantage for it would be immense," Miesenböck said. "The fact that no such animal exists indicates that sleep is really vital, but we don't know why." But Miesenböck is part of team of sleep researchers who believe they are inching closer to to an answer. In a paper published in the journal Nature on Wednesday, they describe a cluster of two dozen brain cells in fruit flies that operate as a homeostatic sleep switch, turning on when the body needs rest and off again when it's time to wake up. "It's like a thermostat," Miesenböck said of the switch, "But instead of responding to temperature it responds to something else." If he and his colleagues could find out what that "something" is, "we might have the answer to the mystery of sleep."

Related chapters from BP7e: 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: 22516 - Posted: 08.04.2016

By Alice Klein The debate has finally been put to bed. Wearable brainwave recorders confirm that birds do indeed sleep while flying, but only for brief periods and usually with one half of their brain. We know several bird species can travel vast distances non-stop, prompting speculation that they must nap mid-flight. Great frigatebirds, for example, can fly continuously for up to two months. On the other hand, the male sandpiper, for one, can largely forgo sleep during the breeding season, hinting that it may also be possible for birds to stay awake during prolonged trips. To settle this question, Niels Rattenborg at the Max Planck Institute for Ornithology in Seewiesen, Germany, and his colleagues fitted small brain activity monitors and movement trackers to 14 great frigatebirds. During long flights, the birds slept for an average of 41 minutes per day, in short episodes of about 12 seconds each. By contrast, they slept for more than 12 hours per day on land. Frigatebirds in flight tend to use one hemisphere at a time to sleep, as do ducks and dolphins, but sometimes they used both. “Some people thought that all their sleep would have to be unihemispheric otherwise they would drop from the sky,” says Rattenborg. “But that’s not the case – they can sleep with both hemispheres and they just continue soaring.” Sleep typically took place as the birds were circling in rising air currents, when they did not need to flap their wings. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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: 22509 - Posted: 08.03.2016

Aaron E. Carroll I remember thinking, after my pregnant wife’s water broke, minutes after I went to bed, anguishing really, over one thought as we drove to the hospital: “I’m never going to be well rested again.” If there’s one things all new parents wish for, it’s a good night’s sleep. Unfortunately, infants sometimes make that impossible. They wake up repeatedly, needing to be fed, changed and comforted. Eventually, they reach an age when they should sleep through the night. Some don’t, though. What to do with them continues to be a topic of a heated debate in parenting circles. One camp believes that babies should be left to cry it out. These people place babies in their cribs at a certain time, after a certain routine, and don’t interfere until the next morning. No matter how much the babies scream or cry, parents ignore them. After all, if babies learn that tantrums lead to the appearance of a loved one, they will continue that behavior in the future. The official name for this intervention is “Extinction.” The downside, of course, is that it’s unbelievably stressful for parents. Many can’t do it. And not holding fast to the plan can make everything worse. Responding to an infant’s crying after an extended period of time makes the behavior harder to extinguish. To a baby, it’s like a slot machine that hits just as you’re ready to walk away; it makes you want to play more. A modification of this strategy is known as “Graduated Extinction.” Parents allow their infant to cry it out for a longer period each night, until infants eventually put themselves to sleep. On the first night, for instance, parents might commit to not entering the baby’s room for five minutes. The next night, 10 minutes. Then 15, and so on. Or, they could increase the increments on progressive checks each night. When they do go in the room, it’s only to check and make sure the baby is O.K. – no picking up or comforting. This isn’t meant to be a reward for crying, but to allow parents to be assured that nothing is wrong. © 2016 The New York Times Company

Related chapters from BP7e: 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, Learning, and Development
Link ID: 22499 - Posted: 08.01.2016

By Richard Kemeny Sleep is essential for memory. Mounting evidence continues to support the notion that the nocturnal brain replays, stabilizes, reorganizes, and strengthens memories while the body is at rest. Recently, one particular facet of this process has piqued the interest of a growing group of neuroscientists: sleep spindles. For years these brief bursts of brain activity have been largely ignored. Now it seems that examining these neuronal pulses could help researchers better understand—perhaps even treat—cognitive impairments. Sleep spindles are a defining characteristic of stage 2 non-rapid eye movement (NREM) sleep. These electrical bursts between 10-16 Hz last only around a second, and are known to occur in the human brain thousands of times per night. Generated by a thin net of neurons enveloping the thalamus, spindles appear across several regions of the brain, and are thought to perform various functions, including maintaining sleep in the face of disturbances in the environment. It appears they are also a fundamental part of the process by which the human brain consolidates memories during sleep. A memory formed during the day is stored temporarily in the hippocampus, before being spontaneously replayed during the night. Information about the memory is distributed out and integrated into the neocortex through an orchestra of slow-waves, spindles, and rapid hippocampal ripples. Spindles, it seems, could be a guiding force—providing the plasticity and coordination needed for this delicate, interregional transfer of information. © 1986-2016 The Scientist

Related chapters from BP7e: 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, Learning, and Development
Link ID: 22494 - Posted: 07.30.2016

By Emma Bryce In 1999, neuroscientist Gero Miesenböck dreamed of using light to expose the brain's inner workings. Two years later, he invented optogenetics, a technique that fulfils this goal: by genetically engineering cells to contain proteins that make them light-responsive, Miesenböck found he could shine light at the brain and trigger electrical activity in those cells. This technique gave scientists the tools to activate and control specific cell populations in the brain, for the first time. For example, Miesenböck, who directs the Centre for Neural Circuits and Behaviour at the University of Oxford, first used optogenetics to activate courtship responses in fruit flies, and even make headless flies take flight - groundbreaking experiments that allowed him to examine, in unprecedented detail, how neurons drive behaviour. Gero Miesenböck: There was almost a "eureka" moment. As is often the case, you tend to have your best ideas when you're not trying to have them: suddenly I had this idea - which I must have been incubating for a long time, because I was thinking about manipulating neurons in the brain genetically to emit light so I could visualise their activity. Suddenly I thought, "What if we just turn the thing upside down, and instead of reading activity, write activity using light and genetics?" That was the real breakthrough idea, and then of course came the big challenge of having to make it work. Brains are composed of many different kinds of nerve cells, and they are genetically distinct from one another. To deconstruct how the brain works we need to pinpoint the roles these individual classes of cells play in processing information. Optogenetics uses the genetic signatures that define individual cell types to address them selectively in the intact brain - that's the "genetics" component. The "opto" component is to use these genetic signatures to place light-sensitive molecules that are encoded in DNA within these cells.

Related chapters from BP7e: 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: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 22469 - Posted: 07.23.2016

You drift off to dreamland just fine but then something, a noise, a partner's tossing and turning, jars you awake. Now your mind races with an ever expanding to-do list of worries that you can't shut off. When the alarm buzzes, you start the day feeling grouchy and slightly dazed. Nearly six in 10 Canadians say they wake up feeling tired. About 40 per cent of Canadians will exhaust themselves with a sleep disorder at some point in their lifetime, studies suggest. It's common for people to wake up in the middle of the night. What's important is not to let it snowball, sleep specialists say. Our sleep cycles include brief periods of wakefulness but deep sleep makes us forget about these awakenings. "It's normal to have one or two a night," said Dr. Brian Murray, a sleep neurologist at Sunnybrook Health Sciences Centre and a professor at the University of Toronto. "It's when it's multiple that I worry." Sleep experts say if someone wakes up multiple times a night, it's a red flag. Chronic sleep problems are linked to heart disease, high blood pressure and some cancers. It can also affect hormone levels, which increases the risk of obesity and Type 2 diabetes, sleep specialists say. Julie Snyder of Toronto said she has stretches of days or weeks when she'll consistently wake up at 1:15 a.m., and again at 4 a.m. The broken sleep leaves her feeling short on patience. ©2016 CBC/Radio-Canada.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22463 - Posted: 07.21.2016

By Clare Wilson It is one of life’s great enigmas: why do we sleep? Now we have the best evidence yet of what sleep is for – allowing housekeeping processes to take place that stop our brains becoming overloaded with new memories. All animals studied so far have been found to sleep, but the reason for their slumber has eluded us. When lab rats are deprived of sleep, they die within a month, and when people go for a few days without sleeping, they start to hallucinate and may have epileptic seizures. One idea is that sleep helps us consolidate new memories, as people do better in tests if they get a chance to sleep after learning. We know that, while awake, fresh memories are recorded by reinforcing connections between brain cells, but the memory processes that take place while we sleep have remained unclear. Support is growing for a theory that sleep evolved so that connections in the brain can be pruned down during slumber, making room for fresh memories to form the next day. “Sleep is the price we pay for learning,” says Giulio Tononi of the University of Wisconsin-Madison, who developed the idea. Now we have the most direct evidence yet that he’s right. Tononi’s team measured the size of these connections or synapses in brain slices taken from mice. The synapses in samples taken at the end of a period of sleep were 18 per cent smaller than those in samples taken from before sleep, showing that the synapses between neurons are weakened during slumber. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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, Learning, and Development
Link ID: 22424 - Posted: 07.12.2016

Laurel Hamers Even Amelia Earhart couldn’t compete with the great frigate bird. She flew nonstop across the United States for 19 hours in 1932; the frigate bird can stay aloft up to two months without landing, a new study finds. The seabird saves energy on transoceanic treks by capitalizing on the large-scale movement patterns of the atmosphere, researchers report in the July 1 Science. By hitching a ride on favorable winds, the bird can spend more time soaring and less time flapping its wings. “Frigate birds are really an anomaly,” says Scott Shaffer, an ecologist at San Jose State University in California who wasn’t involved in the study. The large seabird spends much of its life over the open ocean. Both juvenile and adult birds undertake nonstop flights lasting weeks or months, the scientists found. Frigate birds can’t land in the water to catch a meal or take a break because their feathers aren’t waterproof, so scientists weren’t sure how the birds made such extreme journeys. Researchers attached tiny accelerometers, GPS trackers and heart rate monitors to great frigate birds flying from a tiny island near Madagascar. By pooling data collected over several years, the team re-created what the birds were doing minute-by-minute over long flights — everything from how often the birds flapped their wings to when they dived for food. © Society for Science & the Public 2000 - 2016.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22387 - Posted: 07.01.2016

By Tanya Lewis The human brain may wind down when asleep, but it doesn’t lose all responsiveness. Researchers from the École Normale Supérieure in Paris and their colleagues recently used electroencephalography (EEG) to monitor the brains of volunteers listening to recordings of spoken words, which they were asked to classify as either objects or animals. Participants were able to classify words during light non-REM (NREM) sleep, but not during either deep NREM sleep or REM sleep, according to a study published today (June 14) in The Journal of Neuroscience. “With an elegant experimental design and sophisticated analyses of neural activity, [the authors] demonstrate the extent to which the sleeping brain is able to process sensory information, depending on sleep depth [or] stage,” Thomas Schreiner of the University of Fribourg in Switzerland, who was not involved in the study, wrote in an email to The Scientist. During sleep, the brain is thought to block out external stimuli through a gating mechanism at the level of the thalamus. But experiments dating back to the 1960s have shown that certain types of stimuli, such as hearing one’s name, can filter through and trigger awakening. However, the mechanisms that allow the brain to selectively take in information during sleep remain unknown. “When we fall asleep, it’s pretty similar to a coma because we lose consciousness of our self and of the [outside] world,” study coauthor Thomas Andrillon, a neuroscientist at the École Normale Supérieure, told The Scientist. The question was “whether the brain could still monitor what was going on around, just to be sure the environment was still safe,” he added. © 1986-2016 The Scientist

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 14: Attention and Consciousness
Link ID: 22334 - Posted: 06.18.2016

By Karen Weintraub Many people think they can teach themselves to need less sleep, but they’re wrong, said Dr. Sigrid Veasey, a professor at the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania’s Perelman School of Medicine. We might feel that we’re getting by fine on less sleep, but we’re deluding ourselves, Dr. Veasey said, largely because lack of sleep skews our self-awareness. “The more you deprive yourself of sleep over long periods of time, the less accurate you are of judging your own sleep perception,” she said. Multiple studies have shown that people don’t functionally adapt to less sleep than their bodies need. There is a range of normal sleep times, with most healthy adults naturally needing seven to nine hours of sleep per night, according to the National Sleep Foundation. Those over 65 need about seven to eight hours, on average, while teenagers need eight to 10 hours, and school-age children nine to 11 hours. People’s performance continues to be poor while they are sleep deprived, Dr. Veasey said. Extended vacations are the best times to assess how much sleep you truly need. Once you catch up on lost sleep and are not sleep deprived, the amount you end up sleeping is a good measure how much you need every night. You can ask yourself the questions, “Do you feel that your brain is much sharper, your temper is better, you’re paying attention more effectively? If those answers are yes, than definitely get the sleep,” said Dr. Veasey, who realized -- to her chagrin -- that she needs nine hours of sleep a night to function effectively. Health issues like pain, sleep apnea or autoimmune disease can increase people's need for sleep, said Andrea Meredith, a neuroscientist at the University of Maryland School of Medicine. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22333 - Posted: 06.18.2016

By Ashley P. Taylor Sleep is known to aid memory and learning. For example, people who learn something, sleep on it, and are tested on the material after they wake up tend to perform better than those who remain awake in the interim. Within that general phenomenon, however, there’s a lot of unexplained variation. University of California, Riverside, sleep researcher Sara Mednick wondered “what else might be going during that sleep period that helps people’s memories,” she told The Scientist. As it turns out, activity of the autonomic nervous system (ANS) explains a large part of this variation, Mednick and colleagues show in a paper published today (June 13) in PNAS. The researchers measured not only the electrical activity of the brain during sleep, but also that of the heart, providing an indicator of ANS activity. They found that the beat-to-beat variation in heart rate accounted for much of the previously unexplained variation in how well people performed on memory and creativity tests following a nap. “There is a good possibility that this additional measure [heart-rate variability] may help account for discrepant findings in the sleep-dependent memory consolidation literature,” sleep and cognition researcher Rebecca Spencer of the University of Massachusetts, Amherst, who was not involved in the work, wrote in an email. “Perhaps we put too large of a focus on sleep physiology from the CNS [central nervous system] and ignore a significant role of the ANS.” © 1986-2016 The Scientist

Related chapters from BP7e: 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, Learning, and Development
Link ID: 22323 - Posted: 06.15.2016

By Ian Randall As if you needed another reason to hate the gym, it now turns out that exercise can exhaust not only your muscles, but also your eyes. Fear not, however, for coffee can perk them right up again. During strenuous exercise, our muscles tire as they run out of fuel and build up waste products. Muscle performance can also be affected by a phenomenon called “central fatigue,” in which an imbalance in the body’s chemical messengers prevents the central nervous system from directing muscle movements effectively. It was not known, however, whether central fatigue might also affect motor systems not directly involved in the exercise itself—such as those that move the eyes. To find out, researchers gave 11 volunteers a carbohydrate solution either with a moderate dose of caffeine—which is known to stimulate the central nervous system—or as a placebo without, during 3 hours of vigorous cycling. After exercising, the scientists tested the cyclists with eye-tracking cameras to see how well their brains could still control their visual system. The team found that exercise reduced the speed of rapid eye movements by about 8%, impeding their ability to capture new visual information. The caffeine—the equivalent of two strong cups of coffee—was sufficient to counteract this effect, with some cyclists even displaying increased eye movement speeds, the team reports today in Scientific Reports. So it might be a good idea to get someone else to drive you home after that marathon. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 5: The Sensorimotor System
Link ID: 22243 - Posted: 05.25.2016