Chapter 14. Biological Rhythms, Sleep, and Dreaming

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


Links 81 - 100 of 1427

By Anna Azvolinsky In January 1983, 22-year-old Amita Sehgal arrived in New York City from India to visit her oldest sister, who was due to have a baby. Sehgal had just been rejected from the molecular biology PhD programs at Rockefeller University and Columbia University. “I felt that I had no prospects,” says the University of Pennsylvania professor of neuroscience. She had heard about a Cornell University in NYC, so she and her other sister walked the streets of Manhattan asking its whereabouts. “Someone told us Cornell was hundreds of miles away in Ithaca, and that I must have been asking about the medical school. I had no idea, but I said ‘Yes’ and was directed to the Upper East Side.” Sehgal walked into the medical school, inquired about their PhD program, and was told that the application deadline for the program was that very day. “I sat in the office and filled out the application, wrote my essay, and handed it in!” she says. A few months later, Sehgal was admitted into the genetics program. Sehgal’s parents had also joined the visit and were returning to India in July, shortly before she started the PhD program. “It was fortuitous the way things worked out. My parents were comfortable leaving me in New York because my oldest sister was living there.” One month later, however, her sister and family moved to Florida, and Sehgal was alone, living in Cornell housing. “The first six months were really, really rough,” she says. Cornell had dissolved the genetics program to which Sehgal had been admitted and offered her tuition support with no stipend—and that only for the first semester. “My parents and sister were in no position to help me financially,” she says. Sehgal found a professor at the adjacent Memorial Sloan Kettering Cancer Center (MSKCC), Raju Chaganti, who gave her part-time work with no expectation that she join his lab. She had little money and survived on ramen noodles. © 1986-2016 The Scientist

Keyword: Sleep
Link ID: 22850 - Posted: 11.10.2016

Ian Sample Science editor US military scientists have used electrical brain stimulators to enhance mental skills of staff, in research that aims to boost the performance of air crews, drone operators and others in the armed forces’ most demanding roles. The successful tests of the devices pave the way for servicemen and women to be wired up at critical times of duty, so that electrical pulses can be beamed into their brains to improve their effectiveness in high pressure situations. The brain stimulation kits use five electrodes to send weak electric currents through the skull and into specific parts of the cortex. Previous studies have found evidence that by helping neurons to fire, these minor brain zaps can boost cognitive ability. The technology is seen as a safer alternative to prescription drugs, such as modafinil and ritalin, both of which have been used off-label as performance enhancing drugs in the armed forces. But while electrical brain stimulation appears to have no harmful side effects, some experts say its long-term safety is unknown, and raise concerns about staff being forced to use the equipment if it is approved for military operations. Others are worried about the broader implications of the science on the general workforce because of the advance of an unregulated technology. © 2016 Guardian News and Media Limited

Keyword: Learning & Memory; Sleep
Link ID: 22844 - Posted: 11.08.2016

Anesthesia during early childhood surgery poses little risk for intelligence and academics later on, the largest study of its kind suggests. The results were found in research on nearly 200,000 Swedish teens. School grades were only marginally lower in kids who'd had one or more common surgeries with anesthesia before age 4, compared with those who'd had no anesthesia during those early years. Whether the results apply to sicker children who have riskier surgeries with anesthesia is not known. But the researchers from Sweden's Karolinska Institute and doctors elsewhere called the new results reassuring, given experiments in young animals linking anesthesia drugs with brain damage. Previous studies of children have been relatively small, with conflicting results. The new findings, published Monday in JAMA Pediatrics, don't provide a definitive answer and other research is ongoing. The study authors and other doctors say the harms from postponing surgery must be considered when evaluating any potential risks from anesthesia in young children. The most common procedures in the study were hernia repairs; ear, nose or throat surgeries; and abdominal operations. The researchers say the operations likely lasted an hour or less. The study did not include children with other serious health problems and those who had more complex or risky operations, including brain, heart and cancer surgeries. The research involved about 33,500 teens who'd had surgery before age 4 and nearly 160,000 who did not. ©2016 CBC/Radio-Canada.

Keyword: Development of the Brain; Sleep
Link ID: 22842 - Posted: 11.08.2016

By CLAIRE CAIN MILLER and AARON E. CARROLL New parents get a lot of advice. It comes from breast-feeding “lactivists” and Ferberizers, attachment parents and anti-helicopter ones. It’s not enough to keep babies fed, rested and changed — they also need to learn grit and sign language. So when the American Academy of Pediatrics recently issued new infant sleep guidelines — highlighting a recommendation that babies sleep in their parents’ rooms for at least six months but ideally a full year — some parents despaired. The academy said that sharing a room could cut babies’ chance of dying in their sleep by “up to 50 percent.” Suffocation, strangulation or sudden infant death syndrome, known as SIDS, kills 3,500 babies a year in this country. The academy’s previous recommendations — place babies on their backs to sleep, without loose bedding, in their own cribs — have been an undisputed success in helping to cut SIDS deaths by 53 percent from 1992 to 2001, but SIDS is still the largest cause of infant mortality in the United States after the first month of life. Yet the recommendation drew skepticism from some doctors, who argued that a close look at the evidence showed that the benefits of room-sharing didn’t always justify its costs to parents, who would have to sacrifice privacy, sex and, above all, sleep. Sharing a room can make breast-feeding and bonding easier. It has historically been common around the world, and many parents do it by choice or necessity. But the evidence is not conclusive, and doctors need to understand the trade-offs before demanding that parents follow the recommendation. Doing so will be part of making parenthood possible in a society in which most parents work, yet receive less government support than in any other industrialized country. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22834 - Posted: 11.05.2016

Bedtime use of cellphones or tablets by children — even just having access to them — is consistently linked to excessive daytime sleepiness and poor sleep, researchers say. They called on teachers, health care professionals, parents and children to be educated about the damaging influence of device use on sleep. The portable media devices have entered the bedroom, giving children unprecedented access to technology and media before researchers have had a chance to explore the positive and negative impacts. To explore whether there's an association between use of, or access to, media devices and sleep quantity and quality, researchers reviewed 20 sleep studies involving 125,198 children aged six to 19. In Monday's issue of JAMA Pediatrics, the reviewers concluded there's strong and consistent evidence of an association between access to or use of devices and reduced sleep quantity (defined as less than 10 hours for children and less than nine hours for adolescents) or quality, as well as increased daytime sleepiness. The way device use leads to poor sleep is thought to be light emission. But the review looked at examples of holding a device in the bedroom and not using it, which excludes light emission as the sole mechanism, said study author Ben Carter of the Institute of Psychiatry, Psychology and Neuroscience at King's College London. "We are presenting results that highlight that it looks likely there are also other causes," Carter said in an email. ©2016 CBC/Radio-Canada.

Keyword: Sleep
Link ID: 22812 - Posted: 11.01.2016

Ramin Skibba Some common swifts spend ten months in flight without taking a break, setting a flight record that would be the envy of Amelia Earhart and Charles Lindbergh. Researchers report these long hauls, which occurred during migrations between Scandinavia and central Africa, on 27 October in Current Biology1. Ornithologists and birdwatchers have speculated about the long-distance prowess of common swifts (Apus apus) since the 1960s. People had seen the birds fill the sky in Liberia, for example, but couldn't find any nearby roost sites where the birds might land. Scientists attached tags that combined tiny data loggers and accelerometers to the 40-gram birds to record their route and flight activity during their annual journey. The team tracked 13 individual birds, some for multiple seasons, starting and ending at their breeding grounds in Sweden. The researchers found that some of the birds made a few brief night landings in winter but remained airborne for 99% of the time. Three birds didn't touch down once in the entire ten months. “These long-term flights confirm what everybody suspected for quite some time now,” says Felix Liechti of the Swiss Ornithological Institute in Sempach. Other birds can remain aloft for long periods. Alpine swifts (Tachymarptis melba) fly nonstop for half the year during their migrations2. And the much larger frigate birds (Fregata minor) off the coast of Ecuador can go for two months without landing while they forage for food in the ocean. They can even sleep on the wing3. But common swifts are in a class of their own. © 2016 Macmillan Publishers Limited,

Keyword: Sleep
Link ID: 22803 - Posted: 10.28.2016

By Steven C. Pan A good night’s sleep can be transformative. Among its benefits are improved energy and mood, better immune system functioning and blood sugar regulation, and greater alertness and ability to concentrate. Given all of these benefits, the fact that a third of the human lifespan is spent sleeping makes evolutionary sense. However, sleep appears to have another important function: helping us learn. Across a plethora of memory tasks—involving word lists, maze locations, auditory tones, and more—going to sleep after training yields better performance than remaining awake. This has prompted many sleep researchers to reach a provocative conclusion: beyond merely supporting learning, sleep is vital, and perhaps even directly responsible, for learning itself. Recent discoveries from neuroscience provide insights into that possibility. Sleep appears to be important for long-term potentiation, a strengthening of signals between neurons that is widely regarded as a mechanism of learning and memory. Certain memories acquired during the day appear to be reactivated and “replayed” in the brain during sleep, which may help make them longer lasting. In some instances the amount of improvement that occurs on memory tasks positively correlates with the length of time spent in certain stages of sleep. These and other findings are generating great excitement among sleep researchers, as well as prompting heated debates about the degree to which sleep may or may not be involved in learning. To date, most sleep and learning research has focused on recall, which is the capacity to remember information. However, new research by Stéphanie Mazza and colleagues at the University of Lyon, recently published in the journal Psychological Science,suggests another potential benefit of sleep: improved relearning. © 2016 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 22787 - Posted: 10.26.2016

Merrit Kennedy Parents can reduce the risk of sudden infant death syndrome by keeping their child's crib in the same room, close to their bed, according to the American Academy of Pediatrics. That's one of the key recommendations in new guidance released today aimed at preventing SIDS, which claims the lives of approximately 3,500 infants every year in the United States. That number "initially decreased in the 1990s after a national safe sleep campaign, but has plateaued in recent years," the AAP adds. The pediatricians say that children should sleep in the same room but on a separate surface from their parents for at least the first six months of their lives, and ideally the first year. They say that this can halve the risk of SIDS. It also "removes the possibility of suffocation, strangulation, and entrapment that may occur when the infant is sleeping in an adult bed," according to the recommendations. The AAP discourages sharing a bed with an infant. You can read the AAP's full guidance here. These are a few more of the pediatricians' recommendations: Infants under a year old should always sleep lying on their backs. Side sleeping "is not safe and is not advised," the AAP says. Infants should always sleep on a firm surface covered by only a flat sheet. That's because soft mattresses "could create a pocket ... and increase the chance of rebreathing or suffocation if the infant is placed in or rolls over to the prone position." Smoking — both during pregnancy and around the infant after birth — can increase the risk of SIDS. Alcohol and illicit drugs during pregnancy can also contribute to SIDS, and "parental alcohol and/or illicit drug use in combination with bed-sharing places the infant at particularly high risk of SIDS," the pediatricians say. © 2016 npr

Keyword: Sleep; Development of the Brain
Link ID: 22786 - Posted: 10.25.2016

Susan Milius For widemouthed, musical midshipman fish, melatonin is not a sleep hormone — it’s a serenade starter. In breeding season, male plainfin midshipman fish (Porichthys notatus) spend their nights singing — if that’s the word for hours of sustained foghorn hums. Males dig trysting nests under rocks along much of North America’s Pacific coast, then await females drawn in by the crooning. New lab tests show that melatonin, familiar to humans as a possible sleep aid, is a serenade “go” signal, says behavioral neurobiologist Ni Feng of Yale University. From fish to folks, nighttime release of melatonin helps coordinate bodily timekeeping and orchestrate after-dark biology. The fish courtship chorus, however, is the first example of the hormone prompting a launch into song, according to Andrew Bass of Cornell University. And what remarkable vocalizing it is. The plainfin midshipman male creates a steady “mmm” by quick-twitching specialized muscles around its air-filled swim bladder up to 100 times per second in chilly water. A fish can extend a single hum for about two hours, Feng and Bass report October 10 in Current Biology. That same kind of super-fast muscle shakes rattle-snake tails and trills vocal structures in songbirds and bats. |© Society for Science & the Public 2000 - 2016

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 22767 - Posted: 10.19.2016

Laura Sanders When the body’s internal sense of time doesn’t match up with outside cues, people can suffer, and not just from a lack of sleep. Such ailments are similar in a way to motion sickness — the queasiness caused when body sensations of movement don’t match the external world. So scientists propose calling time-related troubles, which can afflict time-zone hoppers and people who work at night, “circadian-time sickness.” This malady can be described, these scientists say, with a certain type of math. The idea, to be published in Trends in Neurosciences, is “intriguing and thought-provoking,” says neuroscientist Samer Hattar of Johns Hopkins University. “They really came up with an interesting idea of how to explain the mismatch.” Neuroscientist Raymond van Ee of Radboud University in the Netherlands and colleagues knew that many studies had turned up ill effects from an out-of-whack circadian clock. Depression, metabolic syndromes and memory troubles have been found alongside altered daily rhythms. But despite these results, scientists don’t have a good understanding of how body clocks work, van Ee says. Van Ee and colleagues offer a new perspective by using a type of math called Bayesian inference to describe the circadian trouble. Bayesian inference can be used to describe how the brain makes and refines predictions about the world. This guesswork relies on the combination of previous knowledge and incoming sensory information (SN: 5/28/16, p. 18). In the case of circadian-time sickness, these two cues don’t match up, the researchers propose. |© Society for Science & the Public 2000 - 2016

Keyword: Sleep
Link ID: 22763 - Posted: 10.18.2016

By PERRI KLASS, M.D. It’s a classic which-came-first question: Is the child not getting enough sleep because of problem behaviors, especially at bedtime, or is the child behaving problematically because of not getting enough sleep? The answers are most likely yes and yes, and the back-and-forth currents can drag a child down developmentally. In an editorial in JAMA Pediatrics in 2015, Michelle M. Garrison, a research assistant professor at the University of Washington in the division of child and adolescent psychiatry, described this intersection of sleep and behavior problems in early childhood as a “feedback whirlpool.” Dr. Garrison was commenting on a longitudinal study of more than 32,000 Norwegian mothers and their children who were followed from birth to age 5; the children with sleep problems at 18 months, including short sleep duration (sleeping 10 hours or less) or frequent nocturnal awakenings (three times a night or more) had more emotional and behavioral problems at the age of 5. This held true even when the researchers adjusted for emotional and behavioral problems already present in the 18-month-olds; compared to children at the same behavioral baseline, the kids with sleep problems ran into more difficulties as they developed. “Sleep really does drive behavior problems and behavior problems are driving sleep problems, it really is bidirectional,” Dr. Garrison said. “A child can start having problems with emotional regulation, melting down more, and that makes it more difficult for the family to do all the things they have to do so the child can get good sleep. Sleep gets worse; behavior gets worse. It can really be an awful cycle for the kid and the family both.” Dr. Oskar Jenni, a professor of developmental pediatrics at Zurich University Children’s Hospital, said that there is a great deal of variation in the individual sleep needs of children at any given age. Parents need to understand their children’s sleep needs and rhythms, since behavior problems can also arise when children are compelled to spend more time in bed than they actually need. “My main message is adjusting bedtime to the needs of the children in both directions,” he said. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22762 - Posted: 10.18.2016

Hannah Devlin Science correspondent Scientists have found the most definitive evidence yet that some people are destined to age quicker and die younger than others - regardless of their lifestyle. The findings could explain the seemingly random and unfair way that death is sometimes dealt out, and raise the intriguing future possibility of being able to extend the natural human lifespan. “You get people who are vegan, sleep 10 hours a day, have a low-stress job, and still end up dying young,” said Steve Horvath, a biostatistician who led the research at the University of California, Los Angeles. “We’ve shown some people have a faster innate ageing rate.” A higher biological age, regardless of actual age, was consistently linked to an earlier death, the study found. For the 5% of the population who age fastest, this translated to a roughly 50% greater than average risk of death at any age. Intriguingly, the biological changes linked to ageing are potentially reversible, raising the prospect of future treatments that could arrest the ageing process and extend the human lifespan. “The great hope is that we find anti-ageing interventions that would slow your innate ageing rate,” said Horvath. “This is an important milestone to realising this dream.” Horvath’s ageing “clock” relies on measuring subtle chemical changes, in which methyl compounds attach or detach from the genome without altering the underlying code of our DNA. © 2016 Guardian News and Media Limited

Keyword: Development of the Brain; Epigenetics
Link ID: 22708 - Posted: 09.29.2016

By Michael Price A deadly disease known as African sleeping sickness has puzzled doctors for decades. It would disappear from villages without a trace, only to re-emerge weeks or months later with no known cause. Frustrated health officials wondered how sleeping sickness could persist when not a single villager or animal—the disease’s only carriers—tested positive for the insect-borne parasite that causes it. Now, scientists may have an answer at last: They’ve discovered the disease was hiding in plain sight this whole time, living in and even transmitting via human skin. African sleeping sickness, also known as African trypanosomiasis, is caused by a microscopic wormlike parasite spread exclusively by the tsetse fly. As such, it’s limited by the fly’s range to sub-Saharan Africa. Locals avoid places where the flies are numerous, but political unrest can displace residents and force them into the path of the disease. Once infected, people have anywhere from weeks to years before the parasite crashes into the brain, causing headaches, tremors, confusion, and paralysis. Those infected also suffer from a disrupted sleep cycle, bouts of random sleepiness and wakefulness that gives the disease its name. Without treatment—toxic drugs that keep patients bedridden for weeks—those infected nearly always slip into a coma and die. In the 1950s and 1960s, health officials got the number of reported cases down to a few thousand per year and were on track to eradicate it, says parasitologist Annette MacLeod of the University of Glasgow in the United Kingdom, who led the new discovery. But despite their best efforts, they could never get rid of the last few thousand cases. © 2016 American Association for the Advancement of Science.

Keyword: Sleep
Link ID: 22691 - Posted: 09.24.2016

By PAGAN KENNEDY In 1914, The Lancet reported on a clergyman who was found dead in a pool; he had left behind this suicide note: “Another sleepless night, no real sleep for weeks. Oh, my poor brain, I cannot bear the lengthy, dark hours of the night.” I came across that passage with a shock of recognition. Many people think that the worst part of insomnia is the daytime grogginess. But like that pastor, I suffered most in the dark hours after midnight, when my desire for sleep, my raging thirst for it, would drive me into temporary insanity. On the worst nights, my mind would turn into a mad dog that snapped and gnawed itself. Though one in 10 American adults suffer from chronic insomnia, we have yet to answer the most fundamental questions about the affliction. Scientists are still arguing about the mechanisms of sleep and the reasons it fails in seemingly healthy people. There are few — if any — reliable treatments for insomnia. At the same time, medical journals warn that bad sleep can fester into diseases like cancer and diabetes. Deep in the night, those warnings scuttle around my mind like rats. About 18 months ago, during a particularly grueling period, I felt so desperate that I consulted yet another doctor — but all he did was suggest the same drugs that had failed me in the past. I was thrown back once again on my own ways of coping. As a child, I had invented mental games to distract myself. For instance, I would compile a list of things and people that made me happy, starting with words that began with A and moving through the alphabet. One night, I was in the Qs, trying to figure out what to add to quesadillas, queer theory and Questlove. Then, suddenly, the game infuriated me — why, why, why did I have to spend hours doing this? In the red glare of the digital clock, my brain rattled its cage. I prepared for a wave of lunacy. But instead of a meltdown, I had a wild idea: What if there was another, easier, way to drive the miserable thoughts from my mind? I began to fantasize about a machine that would do the thinking for me. I pictured it like another brain that would fit on top of my head. The next day, I cobbled together my first insomnia machine. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22667 - Posted: 09.19.2016

Napping for more than an hour during the day could be a warning sign for type-2 diabetes, Japanese researchers suggest. They found the link after analysing observational studies involving more than 300,000 people. UK experts said people with long-term illnesses and undiagnosed diabetes often felt tired during the day. But they said there was no evidence that napping caused or increased the risk of diabetes. The large study, carried out by scientists at the University of Tokyo, is being presented at a meeting of the European Association for the Study of Diabetes in Munich. Their research found there was a link between long daytime naps of more than 60 minutes and a 45% increased risk of type-2 diabetes, compared with no daytime napping - but there was no link with naps of less than 40 minutes. The researchers said long naps could be a result of disturbed sleep at night, potentially caused by sleep apnoea. And this sleeping disorder could increase the risk of heart attacks, stroke, cardiovascular problems and other metabolic disorders, including type-2 diabetes. Sleep deprivation, caused by work or social life patterns, could also lead to increased appetite, which could increase the risk of type-2 diabetes. But it was also possible that people who were less healthy or in the early stages of diabetes were more likely to nap for longer during the day. Shorter naps, in contrast, were more likely to increase alertness and motor skills, the authors said. © 2016 BBC.

Keyword: Sleep; Obesity
Link ID: 22661 - Posted: 09.17.2016

By Krystnell A. Storr This one goes out to the head bobbers, the window seat sleepers, and the open-mouth breathers — there is no shame in being able to fall asleep anywhere, and at any time. Be proud, and, if you can’t help it, snore loud. Scientists have come to a consensus that our bodies definitely need sleep, but we don’t all need the same amount. The next step for them is to figure out where the process of sleep starts and ends in the body. And, like a good movie, one revelation about sleep only leads to another. Think of yourself as a very minor character in the scientific story of fatigue. The real star of this cozy mystery is the fruit fly, an A-lister in sleep science. Thanks to fruit flies, we understand two of the basic factors that govern sleep: a biological clock, which scientists know a lot about, and a homeostatic switch, which they only just discovered and are beginning to understand. Let’s start with this biological clock. The clock that is connected to sleep is controlled by a circadian rhythm and uses environmental cues such as sunlight to tell the body when to wake up. This sun-sleep connection in humans and flies alike got scientists like Russell Foster, a professor at Oxford University in the United Kingdom, asking questions such as: What happens when we don’t have the mechanisms in our eye to distinguish dawn from dusk and send that message to the brain? Why can we still fall asleep according to the circadian rhythm? The answer, Foster said, is that mammals have a third layer of photoreceptors in the eye. It used to be that scientists thought rods and cones, cells that help us process images, were the only ones in the eye that worked to detect light. But when they removed these cells in mice, they noticed that the mice could still keep up with the circadian rhythm. The hidden cells, they found, were intrinsically sensitive to light and acted as a backup measure to keep us on our sleep schedule, whether we can see that the sun is up or not.

Keyword: Biological Rhythms; Sleep
Link ID: 22656 - Posted: 09.15.2016

By Rachel Feltman In the age of the quantified self, products that promise to track your habits and fix your behavior are a dime a dozen. Find out how much you walk; do that more. Find out how much junk you eat; do that less. Correct your posture in real time, and get feedback as you strengthen your pelvic floor muscles. More and more companies are built on the notion that any problem can be solved if you get enough numbers to find a pattern. In that sense, Sense — a sleep tracker made by the start-up Hello — isn't all that unusual. But the company's new lead scientist is just getting his hands on two years of user sleep data, and he seems particularly passionate about using it for good. Matthew Walker, a professor of neuroscience and psychology at the University of California in Berkeley, and director of the U.C. Berkeley Sleep and Neuroimaging Laboratory, does not mince words when it comes to snoozing. "It’s very clear right now that the sleep-loss epidemic is the greatest public health crisis in First World nations of the 21st century," Walker told The Washington Post. "Every disease that is killing us, in First World countries, can be linked to loss of sleep." Indeed, the Centers for Disease Control and Prevention states that lack of sleep — in addition to causing fatal accidents and injuries — has been linked to an increase risk of hypertension, diabetes, depression, obesity and even cancer. Just about all scientists and medical professionals agree that good sleep helps keep the body healthy. © 1996-2016 The Washington Post

Keyword: Sleep
Link ID: 22655 - Posted: 09.15.2016

Susan Milius Contrary to many adorable children’s stories, hibernation is so not sleeping. And most animals can’t do both at the same time. So what’s with Madagascar’s dwarf lemurs? The fat-tailed dwarf lemur slows its metabolism into true hibernation, and stays there even when brain monitoring shows it’s also sleeping. But two lemur cousins, scientists have just learned, don’t multitask. Like other animals, they have to rev their metabolisms out of hibernation if they want a nap. Hibernating animals, in the strictest sense, stop regulating body temperature, says Peter Klopfer, cofounder of the Duke Lemur Center in Durham, N.C. “They become totally cold-blooded, like snakes.” By this definition, bears don’t hibernate; they downregulate, dropping their body temperatures only modestly, even when winter den temperatures sink lower. And real hibernation lasts months, disqualifying short-termers such as subtropical hummingbirds. The darting fliers cease temperature regulation and go truly torpid at night. “You can pick them out of the trees,” Klopfer says. The fat-tailed dwarf lemur, Cheirogaleus medius, was the first primate hibernator discovered, snuggling deep into the softly rotting wood of dead trees. “You’d think they’d suffocate,” he says. But their oxygen demands plunge to somewhere around 1 percent of usual. As trees warm during the day and cool at night, so do these lemurs. When both a tree and its inner lemur heat up, the lemur’s brain activity reflects mammalian REM sleep. |© Society for Science & the Public 2000 - 2016

Keyword: Sleep; Evolution
Link ID: 22631 - Posted: 09.06.2016

By Christof Koch Flies, birds, mice, dogs, monkeys and people all need to sleep. That is, they show daily periods of relative immobility and lack of response to external stimuli, such as light, sound or touch. This reduced sensitivity to external events distinguishes sleep from quiet resting, whereas the capacity to awaken from slumber distinguishes sleep from coma. Why sleep should be such a prominent feature of daily life across the animal kingdom, despite the fact that it leaves the sleeper unable to confront potential threats, remains mysterious. Still, much progress in characterizing the physiology and capabilities of the sleeping brain has occurred over the past century, driven by the ability to record electrical activity of the brain (via electroencephalography, or EEG, on the surface of the skull), of the eyes (via electrooculography, or EOG), and of facial or other muscles (via electromyography, or EMG). For scientists, it is this triad of simultaneous measurements that operationally defines the state of sleep, leading to both surprising and counterintuitive insights. Even without these tools, there are some basic things we do know about sleep. It is essential for our brain to function properly. Most of us have pulled all-nighters or have wanted to sleep but could not, unable to switch off our mind. The next day we are irritable, have trouble keeping our eyes open, and are terrible at tasks that demand sustained attention. Indeed, sleep deprivation causes many traffic accidents—the reason countries have laws that mandate a minimum rest period and maximum working hours for truck drivers. © 2016 Scientific American,

Keyword: Sleep; Laterality
Link ID: 22623 - Posted: 09.03.2016

By Alice Callahan As new parents, Penn State researcher Doug Teti and his wife were co-sleepers, sharing their bed at night with all three of their children, now grown. So when Dr. Teti, a professor of human development and family studies, embarked on an usual study of co-sleeping, bringing cameras into the bedrooms of 139 Pennsylvania couples, he did not expect to see co-sleeping associated with family stress. But to his surprise, many of the parents in the study who co-slept with their children beyond 6 months of age, a group he called “persistent co-sleepers,” did show signs of stress, particularly the mothers. Dr. Teti emphasized that the research isn’t an indictment against co-sleeping, but does suggest that a number of factors, including cultural pressures and an unsupportive spouse, can make longer-term co-sleeping a more stressful experience for some families. “Co-sleeping is simply a practice, just like solitary sleep is a practice,” he said. “It is important for parents to be on the same page about whatever practices with their children they choose to put into effect.” The study, published this month in the journal Developmental Psychology, was unusual in that it tracked 139 couples, mostly married or living together, who generously allowed researchers to peek into their bedrooms with video cameras, recording nighttime interactions with their new babies at five time points in the first year of life. Co-sleeping — defined in this study as room-sharing or bed-sharing, often a mix of the two — was surprisingly common in early infancy. Nearly 75 percent of the parents co-slept with infants early on, and about half were still co-sleeping three months after the birth. But once the babies reached 6 months of age, only one in four babies continued to share a bed or a room with their parents. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22598 - Posted: 08.25.2016