Chapter 14. Biological Rhythms, Sleep, and Dreaming

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By Alice Klein FOR decades, new parents have been warned against sharing a bed with their babies. While snuggling up with your newborn may seem like the most natural thing in the world, prevailing medical advice says this increases the risk of sudden infant death syndrome (SIDS), sometimes called cot death. Instead, doctors say your little ones should sleep in a separate crib in your bedroom. On the other side of the argument are anthropologists and proponents of “attachment parenting”, who believe that infant-parent separation is unnatural and at odds with our evolutionary history. They favour not just room-sharing but bed-sharing – putting them in direct conflict with paediatric advice. This debate was recently reignited by a study suggesting that room-sharing for up to nine months reduces a baby’s sleep, which in theory could have future health consequences. So what’s a sleep-deprived parent to do? Our ancestors slept in direct contact with their young in order to protect them, just as other primates do today, says Helen Ball at Durham University, UK. “Babies respond to close contact – their breathing, blood oxygen and heart rate are on a more even keel.” In Asia and Africa, most babies still share their parents’ beds (see map). But in the West, bed-sharing fell during the industrial revolution as increased wealth let people afford separate rooms and value was placed on teaching early independence. © Copyright New Scientist Ltd.

Keyword: Sleep
Link ID: 23829 - Posted: 07.13.2017

By Linda Geddes Many dangers stalk the bushlands of Tanzania while members of the Hadza people sleep, yet no one keeps watch. There is no need because it seems that natural variation in sleep means there’s rarely a moment when someone isn’t alert enough to raise the alarm. That’s the conclusion of a study that sheds new light on why teenagers sleep late while grandparents are often up at the crack of dawn. Fifty years ago, psychologist Frederick Snyder proposed that animals who live in groups stay vigilant during sleep, by having some stay awake while others rest. However, no one had tested this sentinel hypothesis in humans until now. One way of maintaining this constant vigilance might be by the evolution of different chronotypes – individual differences in when we tend to sleep. This changes as we age, with teenagers shifting towards later bedtimes, and older people towards earlier bedtimes. Would such variability be enough to keep a community safe at night? To investigate, David Samson, then at the University of Toronto in Canada, and his colleagues turned to the Hadza, a group of hunter-gatherers in northern Tanzania. The Hadza sleep in grass huts, each containing one or two adults and often several children. They live in camps of around 30 adults, although several other camps may be close by. Samson recruited 33 adults from two nearby groups of 22 huts and asked them to wear motion-sensors on their wrists to monitor sleep, for 20 days. “It turned out that it was extremely rare for there to be synchronous sleep,” says Samson, now at Duke University in Durham, North Carolina. © Copyright New Scientist Ltd.

Keyword: Sleep; Development of the Brain
Link ID: 23827 - Posted: 07.12.2017

Tina Hesman Saey How well, not how much, people sleep may affect Alzheimer’s disease risk. Healthy adults built up Alzheimer’s-associated proteins in their cerebral spinal fluid when prevented from getting slow-wave sleep, the deepest stage of sleep, researchers report July 10 in Brain. Just one night of deep-sleep disruption was enough to increase the amount of amyloid-beta, a protein that clumps into brain cell‒killing plaques in people with Alzheimer’s. People in the study who slept poorly for a week also had more of a protein called tau in their spinal fluid than they did when well rested. Tau snarls itself into tangles inside brain cells of people with the disease. These findings support a growing body of evidence that lack of Zs is linked to Alzheimer’s and other neurodegenerative diseases. Specifically, “this suggests that there’s something special about deep, slow-wave sleep,” says Kristine Yaffe, a neurologist and psychiatrist at the University of California, San Francisco who was not involved in the study. People with Alzheimer’s are notoriously poor sleepers, but scientists aren’t sure if that is a cause or a consequence of the disease. Evidence from recent animal and human studies suggests the problem goes both ways, Yaffe says. Lack of sleep may make people more prone to brain disorders. And once a person has the disease, disruptions in the brain may make it hard to sleep. Still, it wasn’t clear why not getting enough shut-eye promotes Alzheimer’s disease.

Keyword: Sleep; Alzheimers
Link ID: 23824 - Posted: 07.11.2017

Ian Sample Science editor The secret to a good night’s sleep later in life is having a good reason to get up in the morning, according to US researchers who surveyed people on their sleeping habits and sense of purpose. People who felt they had a strong purpose in life suffered from less insomnia and sleep disturbances than others and claimed to rest better at night as a result, the study found. Jason Ong, a neurologist who led the research at Northwestern University in Chicago, said that encouraging people to develop a sense of purpose could help them to keep insomnia at bay without the need for sleeping pills. More than 800 people aged 60 to 100 took part in the study and answered questions on their sleep quality and motivations in life. To assess their sense of purpose, the participants were asked to rate statements such as: “I feel good when I think of what I’ve done in the past and what I hope to do in the future.” According to Ong, people who felt their lives had most meaning were less likely to have sleep apnea, a disorder that makes the breathing shallow or occasionally stop, or restless leg syndrome, a condition that compels people to move their legs and which is often worse at night. Those who reported the most purposeful lives had slightly better sleep quality overall, according to the study in the journal Sleep Science and Practice. © 2017 Guardian News and Media Limited

Keyword: Sleep; Attention
Link ID: 23819 - Posted: 07.11.2017

By Linda Geddes BILLIONS of dollars have been spent in search of treatments for psychiatric conditions and brain disorders, when a cheap and effective drug may have been right under our noses: light. Now hospitals are turning to light to treat depression, strokes and Parkinson’s disease, using it to hit the reset button on our internal clocks. From green light soothing the pain of migraine, to blue light reducing organ damage during surgery, recent small studies have uncovered some intriguing effects of this therapy. But apart from easing seasonal affective disorder, we’ve been slow to embrace light as a serious contender for treating neurological conditions. We’ve known for 15 years that a special kind of receptor in our eyes transmits information directly to the body’s master clock, as well as other brain areas that control mood and alertness. These cells are particularly responsive to bluish light, including sunlight. These receptors enable light to act as a powerful reset switch, keeping the clock in our brain synced to the outside world. But this clock can fall out of sync or weaken as part of ageing or a range of disorders – a problem doctors are now starting to treat with light. Most hospitals have small windows and 24-hour lighting, both of which might exacerbate health problems. To tackle this, several hospitals in Europe and the US are installing dynamic “solid state” lighting, which changes like daylight over the course of a day. Such lights can, for example, shine bright whitish-blue in the morning, grow warmer and dimmer throughout the day, and turn orange or switch off at night. © Copyright New Scientist Ltd.

Keyword: Biological Rhythms; Stroke
Link ID: 23808 - Posted: 07.06.2017

By NICHOLAS BAKALAR Poor sleep may be an indication of increased risk for Alzheimer’s disease, a new study of older people suggests. Researchers studied 101 cognitively normal people, average age 63, who completed well-validated sleep questionnaires. They analyzed their spinal fluid for the presence of indicators of the plaques and tangles that are characteristic of Alzheimer’s. The study is in Neurology. After controlling for age, a family history of Alzheimer’s, the ApoE gene that increases Alzheimer’s risk and other factors, they found that poor sleep quality, sleep problems and daytime sleepiness were associated with increased spinal fluid indicators of Alzheimer’s disease. The reason for the association is unclear, but at least one animal study found that during sleep the brain’s capacity to clear toxins like beta amyloid, the toxic protein that forms plaques in the brains of those with Alzheimer’s, improves. It may be that poor sleep interferes with this process in people, too. “Not everyone with sleep problems is destined to develop Alzheimer’s disease,” said the senior author, Barbara B. Bendlin, an associate professor of medicine at the University of Wisconsin School of Medicine and Public Health. “We’re looking at groups of people, and over the whole group we find the association of poor sleep with the markers of Alzheimer’s. But when you look at individuals, not everyone shows that pattern.” © 2017 The New York Times Company

Keyword: Alzheimers; Sleep
Link ID: 23806 - Posted: 07.06.2017

Blood samples from infants who died of Sudden Infant Death Syndrome (SIDS) had high levels of serotonin, a chemical that carries signals along and between nerves, according to a study funded in part by the National Institutes of Health. The finding raises the possibility that a test could be developed to distinguish SIDS cases from other causes of sleep-related, unexpected infant death. The study, led by Robin L. Haynes, Ph.D., of Boston Children’s Hospital and Harvard Medical School, appears in the Proceedings of the National Academy of Sciences. NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) provided funding for the work. SIDS is the sudden death of an infant under one year of age that remains unexplained after a complete autopsy and death scene investigation. In the current study, researchers reported that 31 percent of SIDS infants (19 of 61) had elevated blood levels of serotonin. In previous studies, the researchers reported multiple serotonin-related brain abnormalities in SIDS cases, including a decrease in serotonin in regions involved in breathing, heart rate patterns, blood pressure, temperature regulation, and arousal during sleep. Taken together, the researchers wrote, the findings suggest that an abnormality in serotonin metabolism could indicate an underlying vulnerability that increases SIDS risk and that testing blood samples for serotonin could distinguish certain SIDS cases from other infant deaths. However, they caution that more research is needed. NICHD’s Safe to Sleep campaign provides information on ways to reduce the risk of SIDS and other sleep-related causes of infant death.

Keyword: Sleep; Development of the Brain
Link ID: 23804 - Posted: 07.04.2017

By Kerry Grens Until a little more than a decade ago, doctors had few options to treat newborns whose brains were deprived of oxygen or blood at birth, a condition known as perinatal hypoxic-ischemic encephalopathy, or HIE. If babies could be stabilized and kept breathing, physicians and nurses could offer only supportive care and had to watch and wait to see how much brain damage their patients would suffer. “This was a disease where we had no treatment that worked, and [around] 60 percent of these babies were either dying or had a disability,” says Rosemary Higgins, a program scientist at the National Institute of Child Health and Human Development. In 2005, research findings reshaped the field. Higgins and other neonatologists reported the results of a couple of large clinical trials testing the effects of so-called cooling therapy on brain damage. Hundreds of babies suffering from HIE—the effects on the brain of oxygen deprivation during delivery, due to umbilical cord problems, the placenta coming away from the uterus too soon, or other complications—had their temperatures chilled from roughly 37 °C to about 33 °C for 72 hours, then slowly rewarmed (in one study it was whole-body cooling, in the other it was just the head). Although many babies still died of the brain damage or ended up with a severe disability, more fared better in the treatment groups than in the control groups (New Engl J Med, 353:1574-84; The Lancet, 365:663-70). “Cooling was a landmark discovery for this disease,” Higgins says. Finally, doctors (and their patients) weren’t completely helpless. The intervention used in these studies reduced the number of newborns dying or enduring a severe disability to below 50 percent. © 1986-2017 The Scientist

Keyword: Sleep; Development of the Brain
Link ID: 23787 - Posted: 06.29.2017

By Diana Kwon Across the animal kingdom, nearly all creatures sleep or display sleep-like states. The roundworm, Caenorhabditis elegans, does not sleep in a typical day-night cycle like humans and many other animals. Instead, these worms catch most of their z’s while transitioning from one larval stage to another, during a period called lethargus. When these creatures fall asleep, most of their neurons become inactive spontaneously, suggesting that sleep—at least in worms—is a passive state of the brain, according to a study published today (June 22) in Science. “The condition between sleep to wakefulness is probably one of the most drastic changes that our brains undergo,” says Manuel Zimmer, a neuroscientist at the Research Institute of Molecular Pathology at the Vienna Biocenter in Austria. “How a brain can switch between such drastically different states is not really understood.” To investigate this process, Zimmer and colleagues examined the brains of C. elegans. These worms do indeed have primitive brains, yet their nervous system comprises only 302 neurons, making it much easier to tackle than, say, the human brain, with billions of neurons, or even the fly brain, which has around 100,000 nerve cells. Using transgenic worms engineered with a fluorescent indicator that becomes active in response to high calcium levels in neurons (a proxy for neural activity), the researchers imaged the C. elegans brain during the transitions between sleep and wake states by adjusting oxygen levels. Because these soil-dwelling creatures live among low levels of oxygen (10 percent), atmospheric oxygen concentrations (21 percent) induce hyperactivity and wakefulness. © 1986-2017 The Scientist

Keyword: Sleep
Link ID: 23775 - Posted: 06.26.2017

by Laura Sanders When we brought our first baby home from the hospital, our pediatrician advised us to have her sleep in our room. We put our tiny new roommate in a crib near our bed (though other containers that were flat, firm and free of blankets, pillows or stuffed animals would have worked, too). The advice aims to reduce the risk of sleep-related deaths, including sudden infant death syndrome, or SIDS. Studies suggest that in their first year of life, babies who bunk with their parents (but not in the same bed) are less likely to die from SIDS than babies who sleep in their own room. The reasons aren’t clear, but scientists suspect it has to do with lighter sleep: Babies who sleep near parents might more readily wake themselves up and avoid the deep sleep that’s a risk factor for SIDS. That’s an important reason to keep babies close. Room sharing also makes sense from a logistical standpoint. Middle of the night feedings and diaper changes are easier when there’s less distance between you and the babe. But babies get older. They start snoring a little louder and eating less frequently, and it’s quite natural to wonder how long this room sharing should last. That’s a question without a great answer. In November 2016, the American Academy of Pediatrics task force on SIDS updated its sleep guidelines. The earlier recommendation was that babies ought to sleep in parents’ bedrooms for an entire year. The new suggestion softens that a bit to say infants should be there for “ideally for the first year of life, but at least for the first 6 months.” © Society for Science & the Public 2000 - 2017

Keyword: Sleep; Drug Abuse
Link ID: 23766 - Posted: 06.23.2017

Jon Hamilton Thanks to Sigmund Freud, we all know what it means to dream about swords, sticks and umbrellas. Or maybe we don't. "For 100 years, we got stuck into that Freudian perspective on dreams, which turned out to be not scientifically very accurate," says Robert Stickgold, a sleep researcher and associate professor of psychiatry at Harvard Medical School. "So it's only been in the last 15 to 20 years that we've really started making progress." Today, most brain scientists reject Freud's idea that dreams are highly symbolic representations of unconscious (and usually sexual) desire. That dream umbrella, they say, is probably just an umbrella. But researchers are still trying to figure out what dreams do represent, and what their purpose is. "There's not really a solid theory about why dreaming is there," says Benjamin Baird, a postdoctoral fellow at the Center for Sleep and Consciousness at the University of Wisconsin ­– Madison. "It's a big mystery." We all have a future self, a version of us that is better, more successful. It can inspire us to achieve our dreams, or mock us for everything we have failed to become. In this episode of the NPR podcast Invisibilia, hosts Alix Spiegel and Hanna Rosin talk to a woman who believes she can connect with her younger self in dreams. © 2017 npr

Keyword: Sleep
Link ID: 23765 - Posted: 06.23.2017

By Ashley Yeager Researchers led by Bert O’Malley of Baylor College of Medicine in Houston, Texas, identified a set of metabolism and stress genes in mouse liver cells that followed a pattern of expression on a 12-hour cycle—starting in the morning and again in the evening. O’Malley’s team also found that a 12-hour clock, distinct from the 24-hour circadian clock, drives this morning-evening rhythm in gene expression. The clock’s origin, the scientists suggest, may be rooted in organisms’ initial evolution in the ocean millions of years ago. “It’s a provocative argument,” Cambridge University biologist Michael Hastings tells The Scientist in a phone interview. He’s cautious about the claim of an evolutionary connection between the 12-hour clock in sea creatures and the 12-hour cycles seen in mammals. Still, he commends the team on taking a “cross-biology” approach toward exploring 12-hour gene-expression rhythms in a range of animals. In past studies, researchers have shown that coastal sea animals, such as the crustacean Eurydice pulchra have a dominant body clock driven by the 12-hour ebb and flow of the tides. Rhythms of gene expression every 12-hours have also been found in mammals, such as mice. Whether mammals’ 12-hour rhythms are driven by the body’s circadian clock or something else, however, has remained a mystery. Interested in that question and also observations that the time of day can affect humans’ ability to think clearly, handle stress, and respond to medicine, O’Malley and colleagues began to look more closely at mammals’ 12-hour gene-expression rhythms. In the new study, they analyzed gene-expression data of 18,108 mouse liver genes. Using a mathematical technique developed by researchers at Rice University, the team identified 3,652 genes that had 12-hour rhythms that didn’t appear to be associated with the mouse’s circadian clock. © 1986-2017 The Scientist

Keyword: Biological Rhythms
Link ID: 23748 - Posted: 06.17.2017

By Amina Zafar, CBC News When men postpone meal times, it delays one of the body's clocks, British researchers say, a finding that sheds light on a potential way to overcome jet lag and health harms for shift workers. Our bodies run a roughly 24-hour cycle called the circadian or sleep/wake rhythm. It is controlled by a master "clock" in the brain that responds to light signals from the retina, synchronizing other clocks throughout the body. Now investigators have discovered that a five-hour delay in meal time causes a five-hour delay in blood glucose rhythms. "We think this is due to changes in clocks in our metabolic tissues but not the 'master' clock in the brain," said Jonathan Johnston of the University of Surrey, one of the authors of the study published in Thursday's issue of the journal Current Biology. "This work is important because it demonstrates for the first time that a relatively subtle change of standard human feeding pattern re-synchronizes key metabolic rhythms in the body." Currently, people disoriented by the sluggish time warp of jet lag may take melatonin supplements and time their light exposure to help synchronize their clocks. While the study introduces the idea of adding meal timing to the clock reset toolkit, the practical details of how to do so still need to be worked out. In the experiment, 10 healthy young men came to a specialized sleep lab for 13 days. At first, breakfast was set for 30 minutes after waking. Then, after the men got used ©2017 CBC/Radio-Canada.

Keyword: Biological Rhythms; Obesity
Link ID: 23695 - Posted: 06.02.2017

By Mitch Leslie Colin Wahl, a market research consultant in Chapel Hill, North Carolina, was recovering nicely from triple bypass surgery last year when he noticed a white spot on the incision. It proved to be an obstinate infection that required three further surgeries to eradicate. Wahl, now 61, says his mind hasn't been as sharp since. "It's little things mostly related to memory." An avid recreational hockey player, he would forget to bring his skates or sticks to the rink. Certain words became elusive. Just hours after talking to a colleague about Tasmania, he couldn't recall the word. Instead, he says, the phrase "Outback Australia" was stuck in his mind. "I'm trying to remember something and something else slips into that memory slot." Many of us can recount a similar story about a friend, colleague, or loved one—usually elderly—whose mental condition deteriorated after a visit to an operating room. "The comment that ‘So-and-so has never been the same after the operation’ is pervasive," says anesthesiologist Roderic Eckenhoff of the University of Pennsylvania. Often, surgical patients are beset by postoperative delirium—delusions, confusion, and hallucinations—but that usually fades quickly. Other people develop what has been dubbed postoperative cognitive dysfunction (POCD), suffering problems with memory, attention, and concentration that can last months or even a lifetime. POCD not only disrupts patients' lives, but may also augur worse to come. According to a 2008 study, people who have POCD 3 months after they leave the hospital are nearly twice as likely to die within a year as are surgical patients who report no mental setbacks. With the ballooning senior population needing more surgeries, "this is going to become an epidemic," says anesthesiologist Mervyn Maze of the University of California, San Francisco. © 2017 American Association for the Advancement of Science.

Keyword: Attention; Sleep
Link ID: 23691 - Posted: 06.01.2017

By Alice Klein A DRUG normally used to treat narcolepsy and excessive daytime sleepiness also seems to improve symptoms of attention deficit hyperactivity disorder (ADHD) symptoms. The finding supports the idea that ADHD might be a sleep disorder. People who have been diagnosed with ADHD find it difficult to concentrate and are generally hyperactive. But many with the condition also find it difficult to fall asleep and stay asleep at night, and feel drowsy during the day. Could this mean ADHD is a type of sleep disorder? After all, the brain pathways involved in paying attention have also been linked to sleep. And there’s some evidence of similarly disrupted patterns of chemical signalling in the brains of people with sleep disorders and ADHD. One suggestion is that the circadian rhythm that controls our sleep-wake cycle over each 24 hour period may be misaligned in people with ADHD, causing them to be sleepy or alert at the wrong times. This idea inspired Eric Konofal at Robert-Debré Hospital in Paris to try using a drug for narcolepsy and excessive daytime sleepiness to treat ADHD. Mazindol mimics the effects of a brain chemical called orexin, which modulates wakefulness and appetite. It works as a stimulant to keep us awake, and is lacking in people with narcolepsy, who tend to fall asleep at inappropriate times.

Keyword: ADHD; Sleep
Link ID: 23681 - Posted: 05.31.2017

By JUSTIN GILLIS Global warming caused by human emissions of greenhouse gases is having clear effects in the physical world: more heat waves, heavier rainstorms and higher sea levels, to cite a few. In recent years, though, social scientists have been wrestling with a murkier question: What will climate change mean for human welfare? Forecasts in this realm are tricky, necessarily based on a long chain of assumptions. Scientific papers have predicted effects as varied as a greater spread of tropical diseases, fewer deaths from cold weather and more from hot weather, and even bumpier rides on airplanes. Now comes another entry in this literature: a prediction that in a hotter world, people will get less sleep. In a paper published online Friday by the journal Science Advances, Nick Obradovich and colleagues predicted more restless nights, especially in the summer, as global temperatures rise. They found that the poor, who are less likely to have air-conditioning or be able to run it, as well as the elderly, who have more difficulty regulating their body temperature, would be hit hard. If global emissions are allowed to continue at a high level, the paper found, then additional nights of sleeplessness can be expected beyond what people normally experience. By 2050, for every 100 Americans, an extra six nights of sleeplessness can be expected every month, the researchers calculated. By 2099, that would more than double, to 14 additional nights of tossing and turning each month for every 100 people, in their estimation. Researchers have long known that being too hot or too cold at night can disturb anyone’s sleep, but nobody had thought to ask how that might affect people in a world grown hotter because of climate change. Dr. Obradovich is a political scientist who researches both the politics of climate change and its likely human impacts, holding appointments at Harvard and the Massachusetts Institute of Technology. He started the research while completing a doctoral degree at the University of California, San Diego. © 2017 The New York Times Company

Keyword: Sleep
Link ID: 23666 - Posted: 05.27.2017

By Andy Coghlan Burning the midnight oil may well burn out your brain. The brain cells that destroy and digest worn-out cells and debris go into overdrive in mice that are chronically sleep-deprived. In the short term, this might be beneficial – clearing potentially harmful debris and rebuilding worn circuitry might protect healthy brain connections. But it may cause harm in the long term, and could explain why a chronic lack of sleep puts people at risk of Alzheimer’s disease and other neurological disorders, says Michele Bellesi of the Marche Polytechnic University in Italy. Bellesi reached this conclusion after studying the effects of sleep deprivation in mice. His team compared the brains of mice that had either been allowed to sleep for as long as they wanted or had been kept awake for a further eight hours. Another group of mice were kept awake for five days in a row – mimicking the effects of chronic sleep loss. The team specifically looked at glial cells, which form the brain’s housekeeping system. Earlier research had found that a gene that regulates the activity of these cells is more active after a period of sleep deprivation. One type of glial cell, called an astrocyte, prunes unnecessary synapses in the brain to remodel its wiring. Another type, called a microglial cell, prowls the brain for damaged cells and debris. © Copyright New Scientist Ltd.

Keyword: Sleep; Glia
Link ID: 23657 - Posted: 05.24.2017

Susan Milius A question flamingo researchers get asked all the time — why the birds stand on one leg — may need rethinking. The bigger puzzle may be why flamingos bother standing on two. Balance aids built into the birds’ basic anatomy allow for a one-legged stance that demands little muscular effort, tests find. This stance is so exquisitely stable that a bird sways less to keep itself upright when it appears to be dozing than when it’s alert with eyes open, two Atlanta neuromechanists report May 24 in Biology Letters. “Most of us aren’t aware that we’re moving around all the time,” says Lena Ting of Emory University, who measures what’s called postural sway in standing people as well as in animals. Just keeping the human body vertical demands constant sensing and muscular correction for wavering. Even standing robots “are expending quite a bit of energy,” she says. That could have been the case for flamingos, she points out, since effort isn’t always visible. Translate that improbably long flamingo leg into human terms, and the visible part of the leg would be just the shin down. A flamingo’s hip and knee lie inside the bird’s body. Ting and Young-Hui Chang of the Georgia Institute of Technology tested balance in fluffy young Chilean flamingos coaxed onto a platform attached to an instrument that measures how much they sway. Keepers at Zoo Atlanta hand-rearing the test subjects let researchers visit after feeding time in hopes of catching youngsters inclined toward a nap — on one leg on a machine. “Patience,” Ting says, was the key to any success in this experiment. |© Society for Science & the Public 2000 - 2017

Keyword: Sleep
Link ID: 23656 - Posted: 05.24.2017

Nicola Davis Air pollution might be linked to poor sleep, say researchers looking into the impact of toxic air on our slumbers. The study explored the proportion of time participants spent asleep in bed at night compared with being awake – a measure known as sleep efficiency. The results reveal that greater exposure to nitrogen dioxide and small particulates known as PM 2.5s are linked with a greater chance of having low sleep efficiency. That, researchers say, could be down to the impact of air pollution on the body. “Your nose, your sinuses and the back of your throat can all be irritated by those pollutants so that can cause some sleep disruption as well as from breathing issues,” said Martha Billings, assistant professor of medicine at the University of Washington and co-author of the research. Billings added that pollutants entering the blood could have an effect on the brain and hence the regulation of breathing. The study, presented at the American Thoracic Society’s annual international conference, drew on air pollution data captured for nitrogen dioxide and PM2.5 levels over a five-year period in six US cities, including data captured near the homes of the 1,863 participants. The data was then used to provide estimates of pollution levels in the home. Researchers then captured data from medical-grade wearable devices worn by the participants on their wrists over a period of seven consecutive days to monitor fine movements while they slept – an approach that offers insights into how long each participant spent asleep or awake.

Keyword: Sleep; Neurotoxins
Link ID: 23649 - Posted: 05.23.2017

By PERRI KLASS, M.D. Why do children wake up early when they are young but want to stay in bed till noon as teenagers? Experts say it’s biology. Adolescents’ bodies want to stay up late and sleep late, putting them out of sync with what their school schedules demand of them. So kids have trouble waking up, and they often find themselves feeling drowsy in morning algebra class. But that chronic sleepiness can affect their health and well-being, their behavior, and even their safety; it becomes genuinely dangerous when sleepy teenagers get behind the wheel. At a recent conference on adolescent sleep, health and school start times, at which I gave a brief keynote, several experts made compelling arguments supporting the idea that middle and high school start times should shift to 8:30 a.m. or later, as recommended by the American Academy of Pediatrics and the American Academy of Sleep Medicine. Brian Tefft, a senior researcher with the AAA Foundation for Traffic Safety, talked about “drowsy driving.” He cited an annual study that asks, “In the past 30 days how often have you driven when you were so tired that you had a hard time keeping your eyes open?” Over the past five years, on average, a quarter of the 16- to 18-year-old licensed drivers reported driving in that condition at least once, and 2 percent said fairly often or regularly. The argument is that teenagers who face very early school start times are at risk of regular sleep deprivation. Driving after sleeping only four to five hours a night is associated with a similar crash risk as driving with an alcohol level at the legal limit. Sleeping less than four hours puts you at the same risk as driving with double the legal alcohol limit. (This is not only true for adolescents, but for all of us.) Drowsy driving may not be the only risk that tired teenagers take. Wendy Troxel, a clinical psychologist and senior behavioral and social scientist at RAND, talked about the “adolescent health paradox,” that teenagers, who are in a developmental period of physical strength and resilience, face disproportionately high mortality rates. Unintentional injury (especially car crashes) is high on the list of causes, followed by homicide and suicide. © 2017 The New York Times Company

Keyword: Sleep; Development of the Brain
Link ID: 23648 - Posted: 05.23.2017