Chapter 14. Biological Rhythms, Sleep, and Dreaming

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By PENELOPE GREEN At M.I.T.’s Media Lab, the digital futurist playground, David Rose is investigating swaddling, bedtime stories and hammocks, as well as lavender oil and cocoons. Mr. Rose, a researcher, an inventor-entrepreneur and the author of “Enchanted Objects: Design, Human Desire and the Internet of Things,” and his colleagues have been road-testing weighted blankets to induce a swaddling sensation and listening to recordings of Icelandic fairy tales — all research into an ideal sleep environment that may culminate in a nap pod, or, as he said, “some new furniture form.” “For me, it’s a swinging bed on a screened porch in northwestern Wisconsin,” he said. “You can hear the loons and the wind through the fir trees, and there’s the weight of 10 blankets on top of me because it’s a cold night. We’re trying a bunch of interventions.” Meanwhile, at the University of California, Berkeley, Matthew P. Walker, a professor of neuroscience and psychology and the director of the Sleep and Neuroimaging Laboratory there, is working on direct current stimulation as a cure for sleeplessness in the aging brain. Dr. Walker is also sifting through the millions of hours of human sleep data he has received from Sense, a delicately lovely polycarbonate globe designed to look like the National Stadium in Beijing that measures air quality and other intangibles in your bedroom, then suggests tweaks to help you sleep better. “I’ve got a mission,” he said. “I want to reunite humanity with the sleep it is so bereft of.” Sense is the first product made by Hello Inc., a technology company started by James Proud, a British entrepreneur, for which Dr. Walker is the chief scientist. In Paris, Hugo Mercier, a computer science engineer, has invested in sound waves. He has raised over $10 million to create a headband that uses them to induce sleep. The product, called Dreem, has been beta-tested on 500 people (out of a pool of 6,500 applicants, Mr. Mercier said) and will be ready for sale this summer. © 2017 The New York Times Company

Keyword: Sleep
Link ID: 23467 - Posted: 04.08.2017

By PENELOPE GREEN I’m exhausted. Aren’t you? For an article about how Silicon Valley and other innovators have taken on the challenge of sleeplessness, a $32 billion market once populated mostly by mattress and pharmaceutical companies, I tested but a few of the many hundreds of gadgets, apps, podcasts and other inventions now devoted to a good night’s sleep. As the gizmos grow more elaborate, imbued by ever more exotic technologies, they are creating a ruckus in our bedrooms, and sleep experts advocate a simpler approach. Here are a few of their tips (and a gizmo or two): ​Have someone read to you “Sleep With Me,” a wildly popular podcast by Drew Ackerman, a gravelly voiced librarian who tells excruciatingly boring bedtime stories, has millions of fans, but it makes me anxious. Mr. Rose and his colleagues stumbled upon recordings of Icelandic folk tales, which they found incomprehensible, of course, and therefore more soothing and soporific. ​Take a bath Arianna Huffington, author of “The Sleep Revolution: Transforming Your Life, One Night at a Time,” suggests following the bedtime rituals we gave our children. “You didn’t just throw your baby in bed,” she said. “There was a transition. A hot bath makes it easier for you to wash away the day.” ​Tuck in with a weighted blanket At M.I.T.’s Media Lab, the researcher David Rose and his colleagues are investigating what makes an ideal sleep environment. To evoke the feeling of many blankets on a cold night, Mr. Rose turned to the weighted blankets used as sensory therapy for autistic children. © 2017 The New York Times Company

Keyword: Sleep
Link ID: 23466 - Posted: 04.08.2017

A gene variant may explain why some people prefer to stay up late and hate early mornings. The variant is a mutated form of the CRY1 gene, known to play a role in the circadian clock. Michael Young, at The Rockerfeller University, New York, and his team discovered the mutation in a person diagnosed with delayed sleep phase disorder – a condition that describes many so-called “night-owls”. The team found that five of this person’s relatives also had this mutation, all of whom had a history of sleep problems. They then studied six families in Turkey whose members included 39 carriers of the CRY1 variant. The sleep periods of those with the mutation was shifted by 2 to 4 hours, and some had broken, irregular sleep patterns. The mutation seems to slow the body’s internal biological clock, causing people to have a longer circadian cycle and making them stay awake later. The team have calculated that the variant may be present in as many as one in 75 people in some populations, such as Europeans of non-Finnish descent. But those who have a longer circadian cycle need not despair. Young says many people with delayed sleep phase disorder are able to control their sleep cycles by sticking to strict schedules. “It’s a bit like cigarette smoking in that there are things we can do to help the problem before turning to drugs,” he says. Journal reference: Cell, DOI: 10.1016/j.cell.2017.03.027 © Copyright Reed Business Information Ltd.

Keyword: Biological Rhythms; Genes & Behavior
Link ID: 23459 - Posted: 04.07.2017

By Jyoti Madhusoodanan The human body undergoes daily cycles in gene expression, protein levels, enzymatic activity, and overall function. Light is the strongest regulator of the central circadian rhythm. When light strikes a mammal’s eyes, it triggers an electrical impulse that activates neurons in the suprachiasmatic nucleus (SCN), the seat of the brain’s timekeeping machinery. The SCN sets the pace for neuronal and hormonal signals that regulate body temperature, feeding behavior, rest or activity, immune cell functions, and other daily activities, which in combination with direct signals from the SCN keep the body’s peripheral organs ticking in synchrony. Sunlight reaches the eyes, controls the central clock in the brain. The brain, in turn, controls different physiological processes, such as body temperature and rest-activity cycles, which then affect metabolites, hormones, the sympathetic nervous system, and other biological signals. These processes ensure that the different organ systems of the body cycle together. Timing Treatments to the Clock Regulated by peripheral clocks and interactions with other organs, many metabolic pathways in the body peak and ebb in specific circadian patterns. As a result, drugs targeting these pathways can work better when taken at particular times of day. Here are a few examples. © 1986-2017 The Scientist

Keyword: Biological Rhythms
Link ID: 23458 - Posted: 04.07.2017

SAN FRANCISCO — The nose knows when you’re tired. Sleep deprivation seems to increase the brain’s sensitivity to food smells, researchers reported March 27 at the Cognitive Neuroscience Society’s annual meeting in San Francisco. That might make snacks more enticing — helping explain why people who burn the candle at both ends tend to eat more and gain weight. Adults operating on only four hours of sleep inhaled food odors such as those from potato chips and cinnamon rolls, and nonfood smells like fir trees while undergoing functional MRI scans. (The scientists carefully controlled participants’ food intake throughout the day.) A few weeks later, the same participants repeated the experiment — this time with a full eight hours of sleep. When tired, participants showed greater brain activity in two areas involved in olfaction — the piriform cortex and the orbitofrontal cortex — in response to food smells than they did when well rested. That spike wasn’t seen in response to nonfood odors, says study coauthor Surabhi Bhutani, of the Northwestern University Feinberg School of Medicine in Chicago. Though preliminary, the results fit with previous research showing a link between sleep deprivation and both excessive calorie consumption and weight gain (SN: 8/24/13, p. 18). |© Society for Science & the Public 2000 - 2017

Keyword: Sleep; Obesity
Link ID: 23438 - Posted: 04.03.2017

Katherine Whalley The mammalian suprachiasmatic nucleus (SCN) can autonomously generate circadian oscillations in gene expression and neuronal activity, enabling it to fulfil its role as the brain's 'master circadian clock'. Although the contributions of specific neuronal populations to SCN function have begun to be elucidated, the potential influences of SCN astrocytes are relatively unexplored. Brancaccio et al. now reveal an important role for astrocyte–neuron signalling in SCN timekeeping. SCN neurons exhibit circadian oscillations in their intracellular calcium level ([Ca2+]i), peaking during the circadian 'day'. To determine whether similar fluctuations in activity are observed in astrocytes, the authors expressed a genetically encoded reporter of astrocytic [Ca2+]i in organotypic SCN slices. Long-term imaging revealed the presence of circadian oscillations in astrocytic [Ca2+]i, which was at its highest during the circadian 'night' and thus was anti-phasic to that of neurons. Astrocytes release 'gliotransmitters', including glutamate, in response to an increase in [Ca2+]i. When the authors expressed a genetically encoded sensor of the extracellular glutamate concentration ([Glu]e) in SCN slices, they observed circadian oscillations in [Glu]e that were in phase with astrocytic [Ca2+]i. oscillations. That astrocytes were the source of the measured [Glu]e was supported by the fact that the pharmacological inhibition of astrocytic glutamate catabolism or the genetic ablation of astrocytes, respectively, increased or reduced [Glu]e. © 2017 Macmillan Publishers Limited,

Keyword: Biological Rhythms; Glia
Link ID: 23436 - Posted: 04.01.2017

By STEPH YIN For animals that hibernate, making it to spring is no small feat. Torpor — the state of reduced bodily activity that occurs during hibernation — is not restful. By the time they emerge, hibernating animals are often sleep-deprived: Most expend huge bursts of energy to arouse themselves occasionally in the winter so their body temperatures don’t dip too low. This back-and-forth is exhausting, and hibernators do it with little to no food and water. By winter’s end, some have shed more than half their body weight. But just because it’s spring doesn’t mean it’s time to celebrate. Spring means getting ready for the full speed of summer — and after spending a season in slow motion, that requires some ramping up. Here’s a look at what different animals have on the agenda after coming out of winter’s slumber. Black bears emerge from their dens in April, but stay lethargic for weeks. During this so-called walking hibernation, they sleep plenty and don’t roam very far. Though they have lost up to one-third of their body weight over winter, they don’t have a huge appetite right away — their metabolism is not yet back to normal. They snack mostly on pussy willows and bunches of snow fleas. In January or February, some females give birth, typically to two or three cubs. New mothers continue to hibernate, but they go in and out of torpor, staying alert enough to respond to their cubs’ cries. When they emerge from their dens, mama bears find trees with rough bark that her cubs can easily climb for safety. “Slowly, the bears’ metabolism gears up to normal, active levels,” said Lynn Rogers, a bear expert and principal biologist at the Wildlife Research Institute, a nonprofit in Minnesota. “When plants start sprouting on the forest floor, that’s when they start really moving around.” © 2017 The New York Times Company

Keyword: Biological Rhythms
Link ID: 23406 - Posted: 03.25.2017

By Diana Kwon Astrocytes, star-shape glial cells in the brain, were once simply considered support cells for neurons. However, neuroscientists have recently realized they have many other functions: studies have shown that astrocytes are involved in metabolism, learning, and more. In the latest study to investigate astrocytes’ roles in the brain, researchers confirmed these cells played a key role in regulating mouse circadian rhythms. The team’s results were published today (March 23) in Current Biology. “Recent results have indicated that [glia] are actively modulating synaptic transmission, the development of the nervous system, and changes in the nervous system in response to changes in the environment,” said coauthor Erik Herzog, a neuroscientist at Washington University in St. Louis. “So circadian biologists recognized that the system that we study in the brain also had astrocytes and have wondered what role that they might play.” In 2005, Herzog’s team published a seminal study linking glia to mammalian circadian rhythms. By investigating rat and mouse astrocytes in a dish, the researchers discovered that these glial cells showed circadian rhythms in gene expression. Since then, several independent groups have reported evidence to suggest that astrocytes help regulate daily rhythms. However, linking astrocytes to circadian behaviors in mice remained difficult. “I had several folks in the lab over many years [who] were unable to find the tools that would allow us to answer the question definitively: Do astrocytes play a role in scheduling our day?” Herzog recalled. “Then, within the last year or so, some new tools . . . became available for us.”. © 1986-2017 The Scientist

Keyword: Biological Rhythms; Glia
Link ID: 23405 - Posted: 03.25.2017

USA Today Network Josh Hafner , For college students, new parents and employees dogged by deadlines, the all-nighter is nothing new. But going without sleep leaves you basically drunk, putting you at the equivalent of a .1% blood alcohol content as you drive to work, make decisions and interact with others. “The first thing that goes is your ability to think," said Joseph Ojile, M.D., a board member with the National Sleep Foundation. Judgement, memory and concentration all suffer impairment by the body's 17th hour without sleep, he said. “We know at 17 hours, you're at .08% blood alcohol level," he said, the legal standard for drunk driving. "At 24 hours, you’re at 0.1%." Coordination deteriorates as well in those intervening hours, said Ojile, a professor at Saint Louis University School of Medicine. Irritability sets in, too. Pain becomes more acute and the immune system suffers, he said, leaving the body more open to infection. "Here’s the worst part about the lack of judgement," Ojile said. "The person is unaware of their impairment. How scary is that? ‘I’m fine, I’ll just drive home. I’ll do my work at the nuclear plant, no problem. Or fly the plane, no problem.’" It's not entirely clear how the effects worsen past 24 hours, Ojile said, other than they do. The brain starts shutting down in trance-like microsleeps, 15- to 30-second spells that occur without the person noticing. Eventually, not sleeping results in death.

Keyword: Sleep
Link ID: 23404 - Posted: 03.25.2017

Richard A. Friedman Jet lag makes everyone miserable. But it makes some people mentally ill. There’s a psychiatric hospital not far from Heathrow Airport that is known for treating bipolar and schizophrenic travelers, some of whom are occasionally found wandering aimlessly through the terminals. A study from the 1980s of 186 of those patients found that those who’d traveled from the west had a higher incidence of mania, while those who’d traveled from the east had a higher incidence of depression. I saw the same thing in one of my patients who suffered from manic depression. When he got depressed after a vacation to Europe, we assumed he was just disappointed about returning to work. But then he had a fun trip out West and returned home in what’s called a hypomanic state: He was expansive, a fount of creative ideas. It was clear that his changes in mood weren’t caused by the vacation blues, but by something else. The problem turned out to be a disruption in his circadian rhythm. He didn’t need drugs; he needed the right doses of sleep and sunlight at the right time. It turns out that that prescription could treat much of what ails us. Clinicians have long known that there is a strong link between sleep, sunlight and mood. Problems sleeping are often a warning sign or a cause of impending depression, and can make people with bipolar disorder manic. Some 15 years ago, Dr. Francesco Benedetti, a psychiatrist in Milan, and colleagues noticed that hospitalized bipolar patients who were assigned to rooms with views of the east were discharged earlier than those with rooms facing the west — presumably because the early morning light had an antidepressant effect. The notion that we can manipulate sleep to treat mental illness has also been around for many years. Back in the late 1960s, a German psychiatrist heard about a woman in Tübingen who was hospitalized for depression and claimed that she normally kept her symptoms in check by taking all-night bike rides. He subsequently demonstrated in a group of depressed patients that a night of complete sleep deprivation produced an immediate, significant improvement in mood in about 60 percent of the group. © 2017 The New York Times Company

Keyword: Biological Rhythms; Schizophrenia
Link ID: 23350 - Posted: 03.13.2017

By Torah Kachur, A simple, non-invasive, non-medicinal, safe and cheap way to get a better night's sleep is to play some pink noise, according to a study published on Wednesday in the journal Frontiers in Human Neuroscience. Pink noise has more lower octaves than typical white noise and is hardly soothing. For example, it can be one-second pulses of the sound of a rushing waterfall. The short pieces of quick, quiet sounds would be really annoying if you were trying to fall asleep. But the pink noise isn't trying to get you to fall asleep; it's trying to keep you in a very deep sleep where you have slow brainwaves. This is one of our deepest forms of sleep and, in particular, seems to decline in aging adults. "When you play the pulses at particular times during deep sleep, it actually leads to an enhancement of the electrical signal. So it leads to essentially more of a synchronization of the neurons," said Nelly Papalambros, a PhD student at Northwestern University and the first author on the work. The pulses are timed to coincide with your entry into slow wave sleep. They sound to the same beat as your brainwaves, and they seem to increase the effectiveness of your very valuable and very elusive deep sleep. That slow wave sleep is critical for memory consolidation or, basically, your ability to incorporate new material learned that day with old material and memories. ©2017 CBC/Radio-Canada.

Keyword: Sleep; Learning & Memory
Link ID: 23337 - Posted: 03.10.2017

by Laura Sanders If your young child is facing ear tubes, an MRI or even extensive dental work, you’ve probably got a lot of concerns. One of them may be about whether the drugs used to render your child briefly unconscious can permanently harm his brain. Here’s the frustrating answer: No one knows. “It’s a tough conundrum for parents of kids who need procedures,” says pediatric anesthesiologist Mary Ellen McCann, a pediatric anesthesiologist at Boston Children’s Hospital. “Everything has risks and benefits,” but in this case, the decision to go ahead with surgery is made more difficult by an incomplete understanding of anesthesia’s risks for babies and young children. Some studies suggest that single, short exposures to anesthesia aren’t dangerous. Still, scientists and doctors say that we desperately need more data before we really understand what anesthesia does to developing brains. It helps to know this nonanswer comes with a lot of baggage, a sign that a lot of very smart and committed people are trying to answer the question. In December, the FDA issued a drug safety communication about anesthetics that sounded alarming, beginning with a warning that “repeated or lengthy use of general anesthetic and sedation drugs during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester may affect the development of children’s brains.” FDA recommended more conversations between parents and doctors, in the hopes of delaying surgeries that can safely wait, and the amount of anesthesia exposure in this potentially vulnerable population. |© Society for Science & the Public 2000 - 2017.

Keyword: Development of the Brain; Sleep
Link ID: 23319 - Posted: 03.06.2017

Susan Milius Fitbit-style tracking of two wild African elephants suggests their species could break sleep records for mammals. The elephants get by just fine on about two hours of sleep a day. Much of that shut-eye comes while standing up — the animals sleep lying down only once every three or four days, new data show. Most of what scientists previously knew about sleeping elephants came from captive animals, says neuroethologist Paul Manger of the University of the Witwatersrand, Johannesburg. In zoos and enclosures, elephants have been recorded snoozing about three hours to almost seven over a 24-hour period. Monitoring African elephants in the wild, however, so far reveals more extreme behavior. Data are hard to collect, but two females wearing activity recorders for about a month averaged less sleep than other recorded mammals. Especially intriguing is the elephants’ ability to skip a night’s sleep without needing extra naps later, Manger and colleagues report March 1 in PLOS ONE. “The remarkably short amount of sleep in wild elephants is a real elephant in the room for several theories for the function of sleep,” says Niels Rattenborg of the Max Planck Institute for Ornithology in Seewiesen, Germany. Ideas that sleep restores or resets aspects of the brain for peak performance can’t explain animals that sleep only a little and don’t need catch-up rest, says Rattenborg, who wasn’t involved in the elephant study. The results also don’t fit well with the thought that animals need sleep to consolidate memories. “Elephants are usually not considered to be forgetful animals,” he says. |© Society for Science & the Public 2000 - 2017.

Keyword: Sleep; Evolution
Link ID: 23304 - Posted: 03.02.2017

Sleeping too much or too little can increase the likelihood of becoming obese, researchers have discovered. The study found abnormal sleeping patterns increased the risk of being overweight for those genetically predisposed to obesity. The effect was seen regardless of diet, health or socio-demographic group. The University of Glasgow study also found no clear link between sleep duration and body weight in those with a low genetic risk of obesity. Researchers looked at the effects of a short sleep of less than seven hours a night and a long sleep - more than nine hours - along with daytime napping and shift work. Negative effect They found that in people with a high genetic risk of obesity, both short-sleep and long-sleep durations further increased risk of carrying excess weight, compared with people who slept for normal durations of between seven and nine hours a night. Long sleepers with a risk of obesity were about 4kg heavier and short sleepers were about 2kg heavier than those with a similarly high genetic obesity risk with normal sleep durations. The negative affect happened irrespective of what subjects ate, their health concerns or socio-demographic factors, the research team said. The findings, based on data from almost 120,000 UK Biobank participants, showed no obvious link between sleep duration and body weight in those considered to be at a low genetic risk of obesity. Dr Jason Gill, from the Institute of Cardiovascular and Medical Sciences, said: "These data show that in people with high genetic risk for obesity, sleeping for too short or too long a time, napping during the day and shift work appears to have a fairly substantial adverse influence on body weight. © 2017 BBC.

Keyword: Sleep
Link ID: 23303 - Posted: 03.02.2017

Ian Sample Science editor Dozens of British children who developed narcolepsy as a result of a swine flu vaccine could be compensated after the high court rejected a government appeal to withhold payments. Six million people in Britain, and more across Europe, were given the Pandemrix vaccine made by GlaxoSmithKline during the 2009-10 swine flu pandemic, but the jab was withdrawn after doctors noticed a sharp rise in narcolepsy among those who received it. The sleep disorder is permanent and can cause people to fall asleep dozens of times a day. Some narcoleptics have night terrors and a muscular condition called cataplexy that can lead them to collapse on the spot. In 2015, a 12-year-old boy, known as John for the proceedings, was awarded £120,000 by a court that ruled he had been left severely disabled by narcolepsy caused by the vaccine. He was seven when he had the jab and developed symptoms within months. Because of his tiredness, John became disruptive at school and found it almost impossible to make friends. He takes several naps a day, cannot shower or take a bus on his own, and may never be allowed to drive a car. Despite paying out, the Department for Work and Pensions argued John’s disability was not serious enough to warrant compensation and said the court was wrong to take into account how the illness would affect him in the future. But the high court on Thursday rejected the government’s appeal that only the boy’s disability at the time should have been considered. The ruling paves the way for more than 60 other people to claim compensation. © 2017 Guardian News and Media Limited

Keyword: Narcolepsy; Neuroimmunology
Link ID: 23211 - Posted: 02.10.2017

By Julia Shaw We all have times of day when we are not at our best. For me, before 10am, and between 2-4pm, it’s as though my brain just doesn’t work the way it should. I labor to come up with names, struggle to keep my train of thought, and my eloquence drops to the level expected of an eight-year-old. In an effort to blame my brain for this, rather than my motivation, I reached out to a researcher in the area of sleep and circadian neuroscience. Andrea Smit, a PhD student working with Professors John McDonald and Ralph Mistlberger at Simon Fraser University in Canada, was happy to help me find excuses for why my memory is so terribly unreliable at certain times of day. Humans have daily biological rhythms, called circadian rhythms, which affect almost everything that we do. They inform our bodies when it is time to eat and sleep, and they dictate our ability to remember things. According to Smit, “Chronotype, the degree to which someone is a “morning lark” or a “night owl,” is a manifestation of circadian rhythms. In a recent study, Smit used EEG, a type of brain scan, to study the interaction between chronotypes and memory. “Testing extreme chronotypes at multiple times of day allowed us to compare attentional abilities and visual short term memory between morning larks and night owls. Night owls were worse at suppressing distracting visual information and had a worse visual short term memory in the morning as compared with the afternoon,” she says. “Our research shows that circadian rhythms interact with memories even at very early stages of processing within the brain.” © 2017 Scientific American

Keyword: Biological Rhythms; Learning & Memory
Link ID: 23194 - Posted: 02.07.2017

Aylin Woodward Fearful, flighty chickens raised for eating can hurt themselves while trying to avoid human handlers. But there may be a simple way to hatch calmer chicks: Shine light on the eggs for at least 12 hours a day. Researchers at the University of California, Davis bathed eggs daily in light for different time periods during their three-week incubation. When the chickens reached 3 to 6 weeks old, the scientists tested the birds’ fear responses. In one test, 120 chickens were randomly selected from the 1,006-bird sample and placed one by one in a box with a human “predator” sitting visibly nearby. The chickens incubated in light the longest — 12 hours — made an average of 179 distress calls in three minutes, compared with 211 from birds incubated in complete darkness, animal scientists Gregory Archer and Joy Mench report in January in Applied Animal Behaviour Science. Chickens exposed to lots of light as eggs “would sit in the closest part of the box to me and just chill out,” Archer says. The others spent their time trying to get away. How light has its effect is unclear. On commercial chicken farms, eggs typically sit in warm, dark incubation rooms. The researchers are now testing light's effects in large, commercial incubators. Using light exposure to raise less-fearful chickens could reduce broken bones during handling at processing plants, Archer says. It might also decrease harmful anxious behaviors, such as feather pecking of nearby chickens. G. S. Archer and J. A. Mench. Exposing avian embryos to light affects post-hatch anti-predator fear responses. Applied Animal Behaviour Science. Vol. 186, January 2017, p. 80. doi: 10.1016/j.applanim.2016.10.014. © Society for Science & the Public 2000 - 2016

Keyword: Biological Rhythms; Emotions
Link ID: 23193 - Posted: 02.07.2017

Ah, to sleep, perchance … to shrink your neural connections? That's the conclusion of new research that examined subtle changes in the brain during sleep. The researchers found that sleep provides a time when thebrain's synapses — the connections among neurons—shrink back by nearly 20 percent. During this time, the synapses rest and prepare for the next day, when they will grow stronger while receiving new input—that is, learning new things, the researchers said. Without this reset, known as "synaptic homeostasis," synapses could become overloaded and burned out, like an electrical outlet with too many appliances plugged in to it, the scientists said. "Sleep is the perfect time to allow the synaptic renormalization to occur … because when we are awake, we are 'slaves' of the here and now, always attending some stimuli and learning something," said study co-author Dr. Chiara Cirelli of the University of Wisconsin-Madison Center for Sleep and Consciousness. "During sleep, we are much less preoccupied by the external world … and the brain can sample [or assess] all our synapses, and renormalize them in a smart way," Cirelli told Live Science. Cirelli and her colleague, Dr. Giulio Tononi, also of the University of Wisconsin-Madison, introduced this synaptic homeostasis hypothesis (SHY) in 2003. © 2017 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 23186 - Posted: 02.04.2017

Carl Zimmer Over the years, scientists have come up with a lot of ideas about why we sleep. Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators. A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day. In order to learn, we have to grow connections, or synapses, between the neurons in our brains. These connections enable neurons to send signals to one another quickly and efficiently. We store new memories in these networks. In 2003, Giulio Tononi and Chiara Cirelli, biologists at the University of Wisconsin-Madison, proposed that synapses grew so exuberantly during the day that our brain circuits got “noisy.” When we sleep, the scientists argued, our brains pare back the connections to lift the signal over the noise. In the years since, Dr. Tononi and Dr. Cirelli, along with other researchers, have found a great deal of indirect evidence to support the so-called synaptic homeostasis hypothesis. It turns out, for example, that neurons can prune their synapses — at least in a dish. In laboratory experiments on clumps of neurons, scientists can give them a drug that spurs them to grow extra synapses. Afterward, the neurons pare back some of the growth. Other evidence comes from the electric waves released by the brain. During deep sleep, the waves slow down. Dr. Tononi and Dr. Cirelli have argued that shrinking synapses produce this change. © 2017 The New York Times Company

Keyword: Sleep; Learning & Memory
Link ID: 23184 - Posted: 02.03.2017

Ian Sample Science editor As an antidote to one of the ills of modern life, it may leave some quite cold. When the lure of the TV or fiddling on the phone keep you up late at night, it is time to grab the tent and go camping. The advice from scientists in the US follows a field study that found people fell asleep about two hours earlier than usual when they were denied access to their gadgets and electrical lighting and packed off to the mountains with a tent. A weekend in the wilds of the Rocky Mountains in Colorado helped reset people’s internal clocks and reversed the tendency of artificial light to push bedtime late into the night. A spell outdoors, the researchers conclude, could be just the thing for victims of social jetlag who find themselves yawning all day long. “Our modern environment has really changed the timing of our internal clocks, but also the timing of when we sleep relative to our clock,” said Kenneth Wright, director of the sleep and chronobiology lab at the University of Colorado in Boulder. “A weekend camping trip can reset the clock rapidly.” To explore the sleep-altering effects of the natural environment, Wright sent five hardy colleagues, aged 21 to 39, on a six day camping trip to the Rocky Mountains one December. They left their torches and gadgets behind, and had only sunlight, moonlight and campfires for illumination. The campers went to bed on average two and a half hours earlier than they did at home, and racked up nearly 10 hours of sleep per night compared with their usual seven and a half hours. Monitors showed that they were more active in the daytime and were exposed to light levels up to 13 times higher than they typically received at home.

Keyword: Biological Rhythms; Sleep
Link ID: 23183 - Posted: 02.03.2017