Chapter 10. Biological Rhythms and Sleep

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By Nicholas Bakalar Sleeping a lot may increase the risk for stroke, a new study has found. Chinese researchers followed 31,750 men and women whose average age was 62 for an average of six years, using physical examinations and self-reported data on sleep. They found that compared with sleeping (or being in bed trying to sleep) seven to eight hours a night, sleeping nine or more hours increased the relative risk for stroke by 23 percent. Sleeping less than six hours a night had no effect on stroke incidence. The study, in Neurology, also found that midday napping for more than 90 minutes a day was associated with a 25 percent increased risk for stroke compared with napping 30 minutes or less. And people who both slept more than nine hours and napped more than 90 minutes were 85 percent more likely to have a stroke. The study controlled for smoking, drinking, exercise, family history of stroke, body mass index and other health and behavioral characteristics. The reason for the association is unclear, but long sleep duration is associated with increased inflammation, unfavorable lipid profiles and increased waist circumference, factors known to increase cardiovascular risk. © 2019 The New York Times Company

Keyword: Stroke; Sleep
Link ID: 26890 - Posted: 12.12.2019

By Aaron E. Carroll and Austin Frakt Both of us have sleep apnea, and both of us receive treatment that makes a world of difference. It could make a big difference in your life, too. Sleep apnea is quite common, with estimates that it affects up to 17 percent of men 50 to 70, and 10 percent of men 30 to 49. But there’s a problem. In the American health system, we often make it hard for people to get care, and the same is true here. Obstructive sleep apnea is when the upper airway collapses during sleep, leading to periods of, well, not breathing. About 24 million Americans have sleep apnea and don’t know it, research suggests, and many who do know don’t get treatment. The consequences can be severe. It’s a leading cause of vehicle accidents, as apnea-afflicted drivers fall asleep behind the wheel. Snoring and sleep apnea are on the same spectrum and are associated with Type 2 diabetes in adults. Treatment is associated with improvements in insulin resistance. Having sleep apnea, and not treating it, increases the risk of postoperative cardiovascular surgery complications. Treating sleep apnea improves sleep duration and quality. People who sleep better are much happier and healthier in general. Reducing snoring also helps partners sleep better. How hard is it to get used to a mask? We were treated with continuous positive airway pressure (CPAP). It’s intrusive, though not nearly as much as we had feared. Each night we strap on masks connected to CPAP machines. The modern machines are silent. And we both use masks that cover only our nostrils, though others need full face masks. The air that the machines push through the masks keeps our airways open. It takes some getting used to, but we adapted within a week. This isn’t to say that it’s not a big deal for many people — it can be. But it’s not as scary as many fear. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26882 - Posted: 12.09.2019

By Aimee Cunningham Socially isolated and faced with a persistently white polar landscape, a long-term crew of an Antarctic research station saw a portion of their brains shrink during their stay, a small study finds. “It’s very exciting to see the white desert at the beginning,” says physiologist Alexander Stahn, who began the research while at Charité-Universitätsmedizin Berlin. “But then it’s always the same.” The crew of eight scientists and researchers and a cook lived and worked at the German research station Neumayer III for 14 months. Although joined by other scientists during the summer, the crew alone endured the long darkness of the polar winter, when temperatures can plummet as low as –50° Celsius and evacuation is impossible. That social isolation and monotonous environment is the closest thing on Earth to what a space explorer on a long mission may experience, says Stahn, who is interested in researching what effect such travel would have on the brain. Animal studies have revealed that similar conditions can harm the hippocampus, a brain area crucial for memory and navigation (SN: 11/6/18). For example, rats are better at learning when the animals are housed with companions or in an enriched environment than when alone or in a bare cage, Stahn says. But whether this is true for a person’s brain is unknown. Stahn, now at the Perelman School of Medicine at the University of Pennsylvania, and his colleagues used magnetic resonance imaging to capture views of the team members’ brains before their polar stay and after their return. On average, an area of the hippocampus in the crew’s brains shrank by 7 percent over the course of the expedition, compared with healthy people matched for age and gender who didn’t stay at the station, the researchers report online December 4 in the New England Journal of Medicine. © Society for Science & the Public 2000–2019

Keyword: Learning & Memory; Biological Rhythms
Link ID: 26874 - Posted: 12.05.2019

By Joanne Chen I grew up in New England, so you’d think I’d be used to winter by now. But after wearing dozens of puffy coats thin over my lifetime, that’s not the case: I hate the relentless chill, the heavy boots, the darkness. It’s enough to make anyone want to curl up under a blanket and snooze until March. But as Wirecutter’s sleep writer, I also know that many sleep-promoting products don’t actually do much. Winter tiredness is as mental as it is physical, and you need to consider things both in and out of the bedroom to reawaken your fun-loving self. To help make your seven to eight hours of sleep feel exactly that, here are four expert-approved strategies. Shorter days are largely to blame for the blahs. Light controls our circadian rhythm. Its presence suppresses the flow of the sleep hormone melatonin; its absence encourages it. When sunlight takes its own sweet time to arrive in the morning and slinks away before dinner, that sleepy feeling prevails, even if we’ve just slept. To mimic the refreshing effects of a bright spring morning — but in the darkness of 6 a.m. in winter — a sunrise alarm clock might help. We recommend the Philips Wake-Up Light HF3520. Its light gradually fills the room and peaks at the designated time. There’s a backup alarm too, which I set to the sound of birds chirping so I can pretend it’s actually May. A more integrated strategy: Outfit your home with smart bulbs instead, which you can program to brighten just as you would a sunrise alarm clock. If the thought of entering a dark home after work makes you want to ditch all household obligations, you can also arrange lights to turn on before you walk through your door. Philips Hue, Wirecutter’s smart-bulb pick, offers lighting “formulas” such as brighter intensities in the morning and warmer glows in the evening. (While you’re at it, why not program your smart speaker to play whatever song fires you up?) For an extra kick, light therapy lamps — like our pick, the Carex Day-Light Classic Plus Lamp — might help. Doctors often recommend these for seasonal affective disorder (S.A.D.), a type of depression triggered by certain seasons. (Talk to yours about whether the device is appropriate for you and how best to use it.) © 2019 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 26852 - Posted: 11.26.2019

Alejandra Manjarrez Typically, the worm Caenorhabditis elegans falls asleep after it experiences stress or hours of swimming. In a recent study, scientists observed another sleep trigger: being confined to a microfluidic chamber. As such devices are widely used to analyze different worm behaviors, the authors caution that the sleep induction could interfere with data interpretation. The results were published November 6 in Nature Communications. “In our field, microfluidic chambers have become very commonly used, and they are valuable tools for precise environmental control and for neural imaging . . . but what this study highlights is that we are significantly impacting the physiology and behavior of these animals by confining them in such a way,” says Cheryl Van Buskirk, a geneticist at California State University in Northridge. Van Buskirk studies sleep and stress response in worms, but she was not involved in this research. The team first observed this behavior while developing a technique to make electrical measurements of individual cells in worms placed in microfluidic chambers. They noticed that the muscle cells of these animals would not show any activity during some periods of time. Inactivity, however, is not always equivalent to sleep. “There are specific criteria for sleep, so we actually spent a good deal of the [latest] paper testing those specific criteria,” says Daniel Gonzales, who participated in this study as a graduate student at Rice University in Houston, but has now moved to Purdue University in Indiana. They tested, for example, whether this behavior was reversible, if it was associated with a decreased response to stimuli, and if the worms took on a stereotypical sleep posture. They found that, in addition to fulfilling these criteria, this microfluidics-induced quiescence was also regulated by neurons previously reported to control sleep in C. elegans. © 1986–2019 The Scientist.

Keyword: Sleep
Link ID: 26840 - Posted: 11.21.2019

By Kim Tingley We humans spend a third of our lives asleep, oblivious to our surroundings and temporarily paralyzed. It’s a vulnerability that would seem to diminish our odds of survival, so evolutionarily speaking it must also somehow confer tremendous benefits. Yet our best guesses about what those benefits are tend to come from observing what happens when sleep is curtailed. As far as we know, all animals sleep in some way; deprive most of them of it for long enough, and they will die, but exactly why is unclear. In 2015, the American Academy of Sleep Medicine and the Sleep Research Society published a joint statement, based on a comprehensive review of research, saying that “sleeping less than seven hours per night on a regular basis” — which is the case for an estimated 35 to 40 percent of Americans during the workweek — is associated with adverse health outcomes. These include weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, impaired immune function, increased pain, greater likelihood of accidents and “increased risk of death.” The National Institutes of Health reported last year that sleep deficits may increase the beta-amyloid proteins in the brain linked with Alzheimer’s disease. But when it comes to “what sleep is, how much you need and what it’s for,” says Louis Ptacek, a professor of neurology at the University of California, San Francisco, “we know almost nothing — other than it’s bad not to get enough of it.” Indeed, says David Dinges, one of the statement’s authors and a professor of psychiatry at the University of Pennsylvania, “All of this makes it really tough to send out simple messages to the public about when you should sleep and how much you should sleep.” Scientists believe that there are two separate but interrelated internal systems that regulate sleep. The first is the circadian system that tells our body when to sleep. Medicine already knows a great deal about how it works: Approximately every 24 hours, the suprachiasmatic nucleus, a small region in the hypothalamus, orchestrates physiological changes to prepare us for sleep, like lowering body temperature and releasing dopamine. But the second system — the one that tells our body the amount of sleep it needs — is still mysterious. One way to elucidate it would be to find genes that govern how long or deeply people sleep and observe where those genes are active. This fall, Ptacek, Ying-Hui Fu and other colleagues announced, in the journals Neuron and Science Translational Medicine, the discovery of two genetic mutations that seem to cause certain people to sleep far less than average. This brought the number of genes known to be involved in sleep duration to just three. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26833 - Posted: 11.19.2019

By Nicholas Bakalar Poor sleepers may be at increased risk for cardiovascular disease. Chinese researchers used data on 487,200 people ages 30 to 79, generally healthy at the start of the study. The participants reported on the frequency of three symptoms of poor sleep: difficulty falling or staying asleep, daytime sleepiness and early morning awakening. The study is in Neurology. The scientists followed the group for an average of 10 years, during which there were 130,032 cases of cardiovascular disease. After adjusting for age, alcohol consumption, family history of cardiovascular disease and many other factors, they found that difficulty falling asleep was associated with a 9 percent increased relative risk for cardiovascular disease, early morning awakening with a 7 percent increased risk, and daytime sleepiness with a 13 percent increased risk. Compared with those who had no sleep problems, those with all three symptoms had an 18 percent increased relative risk of cardiovascular disease. The link was especially strong in younger people. The lead author, Canqing Yu, an associate professor at Peking University, noted that the sleep data depended on self-reports, and this observational study does not prove cause and effect. “People with difficulty sleeping shouldn’t be alarmed by this finding,” he said. “Poor sleep is a minor contributor to cardiovascular disease. But among young people who have no other risk factors, this can be important.” © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26813 - Posted: 11.12.2019

By Austin Frakt Daylight Saving Time ended on Sunday, and for many of us the extra hour of sleep has provided a small energy boost. It’s widely known that sleep affects our mood and health. Less understood is how it can also affect our paychecks. A study published last year in the Review of Economics and Statistics found that workers who live in locations where people get more sleep tend to earn more than those in areas where people get less. One theory: Better-rested workers are more productive and are compensated for it with additional income. “There are other explanations, but we consider them less likely,” said an author of the study, Matthew Gibson, an economist at Williams College. It’s not as if simply sleeping more will cause your boss to pay you more. In fact, if you get that extra sleep by being late for work, you might earn less or even lose your job. So how would the sleep-income relationship actually work? Studying the issue is complicated by reverse causality: Not only does sleep affect work, but work also affects sleep. On an individual level, people who work more, and earn more for it, often sleep less. Studies show that higher-income earners sleep less than lower-income ones. That could be because higher-income people are spending more time working, so they have less time for sleep. Additionally, working more is stressful, and stress disrupts sleep. But poor sleep contributes to stress, too. A study in Sleep Health found that a poorer night’s sleep is followed by more stress and distracting thoughts at work. Other studies also find that less and poorer sleep is associated with more conflict and stress the next day. © 2019 The New York Times Company

Keyword: Sleep; Stress
Link ID: 26787 - Posted: 11.04.2019

By Laura Sanders Every 20 seconds, a wave of fresh cerebrospinal fluid rolls into the sleeping brain. These slow, rhythmic blasts, described for the first time in the Nov. 1 Science, may help explain why sleep is so important for brain health. Studies on animals have shown that the fluid, called CSF, can wash harmful proteins, including those implicated in Alzheimer’s disease, out of the brain. The new results give heft to the idea that a similar power wash happens in sleeping people. Researchers studied 13 healthy, young people in an MRI scanner as they fell into non-REM sleep, the type of slumber that takes up most of the night. At the same time, the scientists monitored different sorts of activity in participants’ heads. Electrodes measured the activity of large collections of nerve cells, and functional MRI measured the presence of oxygenated blood that gives energy to those nerve cells. By using a form of rapid fMRI, the team also measured another type of activity — the movements of CSF in the brain. Fast fMRI revealed waves of fresh CSF that flowed rhythmically into the sleeping brains, a pattern that was obvious — and big, says study coauthor Laura Lewis, a neuroscientist and engineer at Boston University. “I’ve never had something jump out at me to this degree,” she says. “It was very striking.” Awake people have small, gentle waves of CSF that are largely linked to breathing patterns. In contrast, the sleep waves were tsunamis. “The waves we saw during sleep were much, much larger, and higher velocity,” Lewis says. © Society for Science & the Public 2000–2019

Keyword: Sleep
Link ID: 26781 - Posted: 11.01.2019

By Vanessa Barbara SÃO PAULO, Brazil — It’s hard to feel normal when you wake up at 4 p.m. every day. No, I’m not a nurse who works the evening shift. No, I’m not the hard-partying heir to a Brazilian agribusiness fortune. And before you think it, I’m not lazy, either — I’ve written seven books so far! I sleep until the late afternoon because I’ve finally learned, after fighting it for years, that it’s better to come across as pathetic than to be always exhausted, depressed or sick. I have a severe case of delayed sleep phase syndrome, a chronic misalignment of the body’s circadian rhythms with the daily light-dark cycle of our environment. The phrase “night owl” doesn’t really do it justice; my natural bedtime is around 6 a.m. While we as a culture are gradually becoming more aware of the many ways that bodies can differ from the norm, much of the world still takes for granted that people sleep at night and are awake during the day. Not me. I miss having lunch. According to conventional wisdom, going to bed early and waking up with the birds is a mere matter of habit and will power. This misconception is widespread, even among doctors. And for a long time, I believed it. I spent years taking melatonin and Ambien in order to fall asleep by 2 a.m.; I used to wake up at 11 a.m. and then spend the rest of the day on stimulants such as Provigil and Ritalin. Yet I was always tired and depressed — the outcome that so often results when we try to force ourselves to be different from what we naturally need to be. The last two decades have seen rapid advances in the field of chronobiology, the study of the biochemical clocks that keep our natural physiological rhythms. The 2017 Nobel Prize in Medicine, for instance, was awarded to three American geneticists for their discoveries of molecular mechanisms controlling the circadian rhythms in fruit flies. © 2019 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 26776 - Posted: 10.31.2019

By Gretchen Reynolds Taking more steps during the day may be related to better sleep at night, according to an encouraging new study of lifestyle and sleep patterns. The study, which delved into the links between walking and snoozing, suggests that being active can influence how well we sleep, whether we actually exercise or not. Sleep and exercise scientists have long been intrigued and befuddled by the ties between physical activity and somnolence. To most of us, it might seem as if that relationship should be uncomplicated, advantageous and one-way. You work out, grow tired and sleep better that night. But a variety of past studies indicate that the effects of exercise on sleep are more scrambled than that. In some studies, when people work out strenuously, they sleep relatively poorly, suggesting that intense exercise might disrupt slumber. Other experiments have found that the impacts of exertion and sleep work both ways; after a night of ragged sleep, people often report finding their normal workout extra wearing. Past research also has produced conflicting results about whether and how the timing of exercise matters, and if afternoon workouts aid or impair that night’s sleep. Most of these past studies have focused on planned exercise, though, not more incidental, everyday physical activity, and much of the research has involved people with clinical sleep problems, such as insomnia. Little has been known about whether simply moving around more during the day, absent formal exercise, might influence sleep, particularly in people who already tend to sleep fairly well. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26771 - Posted: 10.30.2019

By Perri Klass, M.D. Sleeping through the night is a hot topic in pediatrics, so it was no surprise that there was a standing-room-only crowd for a lecture on it at the national conference of the American Academy of Pediatrics in New Orleans over the weekend. The speaker, Dr. Adiaha I.A. Spinks-Franklin, a developmental behavioral pediatrician, did her training at Children’s Hospital, Boston, where her teachers included the pediatric sleep expert, Dr. Richard Ferber, whose name has become a verb: “we Ferberized our baby.” But Dr. Spinks-Franklin, an associate professor of pediatrics at Baylor College of Medicine, wasn’t talking about the burning question of whether to let babies cry. In her presentation, “Strategies to Help Sleepless Teens,” she started by reviewing the factors that can contribute to inadequate sleep in adolescents: social media and electronic devices in the bedroom. Intensely caffeinated drinks. The pressures of heavily overloaded schedules, including academic demands, extracurricular activities, travel sports teams, jobs and social lives. The biology of adolescent sleep reflects a natural and normal delay in melatonin secretion that leads to a later sleep onset time, which unfortunately coincides with early high school start times, creating a high-stress set up. Pediatricians often see adolescents with insomnia, who have trouble falling asleep or staying asleep, waking up too early or finding sleep not restful or refreshing. Evaluating insomnia in an adolescents means looking at the predisposing factors, she said, including how that adolescent responds to stress, and possible genetic influences, and the precipitating factors — the specific triggers for insomnia — and finally, the perpetuating factors, which can keep the pattern going. All these adolescents should be screened for depression and anxiety, Dr. Spinks-Franklin said; both can affect sleep onset or sleep maintenance. And both are alarmingly common in adolescents. © 2019 The New York Times Company

Keyword: Sleep; Development of the Brain
Link ID: 26765 - Posted: 10.29.2019

Patti Neighmond More Americans have been getting less than seven hours of sleep a night in the past several years, especially in professions such as health care. ER Productions Limited/Getty Images If you often hit that midafternoon slump and feel drowsy at your desk, you're not alone. The number of working Americans who get less than seven hours of sleep a night is on the rise. And the people hardest hit when it comes to sleep deprivation are those we depend on the most for our health and safety: police and health care workers, along with those in the transportation field, such as truck drivers. In a recent study, researchers from Ball State University in Muncie, Ind., analyzed data from the National Health Interview Survey. They looked at self-reports of sleep duration among 150,000 adults working in different occupations from 2010 to 2018. Researchers found the prevalence of inadequate sleep, defined as seven hours or less, increased from 30.9% in 2010 to 35.6% in 2018. But it was worse for police officers and health care workers. Around half of respondents in these professions reported not getting seven hours a night. For many, the norm was six or even just five hours. The researchers didn't examine why sleep time is dwindling. But Jagdish Khubchandani — professor of health science at Ball State University who headed the study — speculates one of the biggest reasons has to do with stress, which is on the rise among Americans. © 2019 npr

Keyword: Sleep
Link ID: 26764 - Posted: 10.29.2019

By Laura Sanders CHICAGO — Wide swings in blood sugar can mess with sleep. Food’s relationship with sleep gets even more muddled when signs of Alzheimer’s disease are present, a study of mice suggests. The results, presented in a news briefing October 20 at the annual meeting of the Society for Neuroscience, show that Alzheimer’s disease is not confined to the brain. “Your head is attached to your body,” says neuroscientist Shannon Macauley of Wake Forest School of Medicine in Winston-Salem, N.C. Metabolism, sleep and brain health “don’t happen in isolation,” she says. Along with Caitlin Carroll, also of Wake Forest, Macauley and coauthors rigged up a way to simultaneously measure how much sugar the brain consumes, the rate of nerve cell activity and how much time mice spend asleep. Injections of glucose into the blood led to changes in the brain: a burst of metabolism, a bump in nerve cell activity and more time spent awake. “It’s like giving a kid a lollipop,” Macauley says. “They’re going to run around in a circle.” But a dip in blood sugar, caused by insulin injections, also led to more nerve cell action and more wakefulness. “You can have it go up high or go down low, and it was just really bad either way,” Macauley says. Researchers did similar analyses in mice genetically engineered to have one of two key signs of Alzheimer’s. Some of these mice had clumps of amyloid-beta protein between nerve cells, while others had tangles of a protein called tau inside nerve cells. © Society for Science & the Public 2000–2019.

Keyword: Alzheimers; Sleep
Link ID: 26740 - Posted: 10.23.2019

By Eric A. Taub Like clockwork, the sound of the freight train came roaring through our bedroom in the middle of each night. Or at least what sounded like a freight train. In reality, it was me, snoring. And according to my wife, that freight train had gotten considerably louder over the years. Unfortunately, snoring frequency and volume is exacerbated by age, among other factors. While there’s nothing I can do about getting older, there are products and procedures available that can eliminate or significantly reduce the annoyance to one’s bed partner caused by all that nighttime snorting and wheezing. Snoring and sleep apnea are not the same, although severe snoring can be an indication of apnea. If sleep apnea is not present, snoring is simply the benign result of an obstructed airway. As we age, the uvula — that soft, floppy, fingerlike projection in the back of the throat — gets softer and floppier. At the same time, muscles under the tongue get lax. And the condition is exacerbated if we are overweight or drink too much alcohol. “With age, the muscle tone of our airways decreases. That decreased tone allows the tissues to move more readily and become more prone to collapse and to vibrate,” said Dr. Michael D. Olson, an ear, nose and throat doctor and sleep surgeon in the Mayo Clinic’s department of head and neck surgery. In addition, if the size of the airway decreases, air pressure increases, allowing for tissue vibration and snoring. “Combine that with nasal congestion, a big tongue and body fat, and that leads to an excessive collapse of the airways,” Dr. Olson said. Another cause of snoring: teeth extraction, a particular issue for baby boomers who had braces in their youth. With the removal of four bicuspids as a common practice at the time, boomers may now be suffering snoring because of a larger tongue in a smaller mouth. © 2019 The New York Times Company

Keyword: Sleep
Link ID: 26731 - Posted: 10.22.2019

Emma Yasinski Delta waves, patterns of slow, synchronized brain activity that occur during deep sleep, have long been considered “periods of silence,” in which neurons in the cortex stop firing. But these intervals may not be silent after all, researchers reported yesterday in Science. In rats, some cortical neurons remain active during delta waves, and their firing may even be involved in consolidating memories. “The paper is absolutely fascinating and will have a large impact on the field of memory and sleep,” says Björn Rasch, a biopsychologist at the University of Fribourg in Switzerland who was not involved in the study. He suggests it might even help explain surprising results in his own research in humans published earlier this year that indicated participants may better remember words from a foreign language if they are replayed during delta wave sleep than if they are never repeated during sleep. The latest study “challenges our views on the potential function of down states [when cortical neurons seem silent] in memory consolidation processes.” When humans (and rats) are awake, a brain structure called the hippocampus records the ongoing episodes of our lives. When we sleep, the hippocampus replays this activity, which is transmitted to the cortex where it forms long-term memories. Afterward, the cortex seems to go silent. This quiet delta wave period is known to be important for memory consolidation, but researchers have wondered how it helps the process. © 1986–2019 The Scientist.

Keyword: Sleep; Learning & Memory
Link ID: 26730 - Posted: 10.22.2019

By Karen Weintraub We all wish we could get by on less sleep, but one father and son actually can—without suffering any health consequences and while actually performing on memory tests as well as, or better than, most people. To understand this rare ability, researchers at the University of California, San Francisco, first identified a genetic mutation—in both individuals—that they thought might deserve the credit. Then the scientists intentionally made the same small genetic spelling mistake in mice. The mice also needed less sleep, remembered better and suffered no other ill effects, according to a study published today in Science Translational Medicine. Although a medication with the same benefits will not be available anytime soon—and might never materialize—the idea is incredibly appealing: take a pill that replicates whatever the father and son’s body does and sleep less, with no negative repercussions. “I find the concept of a gene product that might potentially provide protection against comorbid disorders of restricted sleep tantalizing,” says Patrick Fuller, an associate professor of neurology at Harvard Medical School and Beth Israel Deaconess Medical Center in Boston, who was not involved with the work. “If true, this would indeed have ‘potential therapeutic implications,’ as well as provide another point of entry for exploring and answering the question ‘Why do we sleep?’ which remains [one] of the greatest mysteries in neuroscience.” © 2019 Scientific American

Keyword: Sleep; Genes & Behavior
Link ID: 26710 - Posted: 10.17.2019

By Emily Willingham Most of us could use more sleep. We feel it in our urge for an extra cup of coffee and in a slipping cognitive grasp as a busy day grinds on. And sleep has been strongly tied to our thinking, sharpening it when we get enough and blunting it when we get too little. What produces these effects are familiar to neuroscientists: external light and dark signals that help set our daily, or circadian, rhythms, “clock” genes that act as internal timekeepers, and neurons that signal to one another through connections called synapses. But how these factors interact to freshen a brain once we do sleep has remained enigmatic. Findings published on October 10 in two papers in Science place synapses at center stage. These nodes of neuronal communication, researchers show, are where internal preparations for sleep and the effects of our sleep-related behaviors converge. Cellular timekeepers rhythmically prep areas around the synapses in anticipation of building synaptic proteins during slumber. But the new findings indicate neurons don’t end up building these critical proteins in the absence of sleep. Advertisement The results suggest the brain is “getting prepared for an event, but it doesn’t mean you actually follow through on doing it,” says Robert Greene, a neuroscientist at the University of Texas Southwestern Medical Center, who was not involved in the study. Greene calls the studies “fascinating,” saying they confirm a “long suspected” connection between internal timekeeping and sleep behaviors. © 2019 Scientific American

Keyword: Sleep
Link ID: 26695 - Posted: 10.11.2019

By Elizabeth Preston Heidi the octopus is sleeping. Her body is still, eight arms tucked neatly away. But her skin is restless. She turns from ghostly white to yellow, flashes deep red, then goes mottled green and bumpy like plant life. Her muscles clench and relax, sending a tendril of arm loose. From the outside, the cephalopod looks like a person twitching and muttering during a dream, or like a napping dog chasing dream-squirrels. “If she is dreaming, this is a dramatic moment,” David Scheel, an octopus researcher at Alaska Pacific University, said in the documentary. Heidi was living in a tank in his living room when her snooze was captured by the film crew, and he speculates that she is imagining catching and eating a crab. But an octopus is almost nothing like a person. So how much can anyone really say with accuracy about what Heidi was doing? When our two branches of the animal family tree diverged, backbones hadn’t been invented. Yet octopuses, cuttlefish and squid, on their own evolutionary path, developed impressive intelligence. They came up with their own way to build big brains. Much of an octopus’s brain is spread throughout its body, especially its arms. It makes sense to be cautious when we guess what’s going on in these animals’ minds. Looking at a behavior like Heidi’s is “a bit like going to a crime scene,” said Nicola Clayton, a psychologist at the University of Cambridge who studies comparative cognition. “You’ve got some evidence in front of you, but you’d need to know so much more to understand better what’s causing the behavior.” It’s only conjecture to say the octopus is dreaming without more data, she said. Does the sequence of Heidi’s color changes match an experience she had while awake? Dreaming in humans mostly happens during rapid-eye movement, or R.E.M., sleep. Could we observe something similar in octopuses? Dr. Clayton points out that a human sleeper might flush red because she’s overheated. © 2019 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 26686 - Posted: 10.09.2019

By Nicholas Bakalar During pregnancy, sleeping on your back may be a bad idea. Previous studies have found that sleeping in a supine position causes compression of veins and arteries that can lead to a reduction in blood flow to the placenta severe enough to double the risk for stillbirth after 28 weeks of gestation. Now a new study, in JAMA Network Open, concludes that supine sleeping is also associated with low birth weight in full-term babies. Of 1,760 pregnant women in the analysis, 57 went to sleep lying on their backs. (The initial sleep position is the one maintained for the longest time during the night.) After controlling for age, body mass index, previous pregnancies, hypertension, diabetes and other factors, they found that compared with those sleeping in other positions, women who slept on their backs had babies who were three times as likely to be in the lowest 10th percentile for birth weight. “It’s a small number of pregnant women who go to sleep on their backs — only about 3 percent,” said the lead author, Dr. Ngaire H. Anderson, a senior lecturer in obstetrics and gynecology at the University of Auckland. “But we are keen to encourage the message that sleeping on one’s side is a way to optimize the baby’s health, both in reducing stillbirth and optimizing the baby’s growth.” © 2019 The New York Times Company

Keyword: Sleep; Development of the Brain
Link ID: 26677 - Posted: 10.08.2019