Chapter 10. Biological Rhythms and Sleep

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By Elizabeth Preston On dry nights, the San hunter-gatherers of Namibia often sleep under the stars. They have no electric lights or new Netflix releases keeping them awake. Yet when they rise in the morning, they haven’t gotten any more hours of sleep than a typical Western city-dweller who stayed up doom-scrolling on their smartphone. Research has shown that people in non-industrial societies — the closest thing to the kind of setting our species evolved in — average less than seven hours a night, says evolutionary anthropologist David Samson at the University of Toronto Mississauga. That’s a surprising number when you consider our closest animal relatives. Humans sleep less than any ape, monkey or lemur that scientists have studied. Chimps sleep around 9.5 hours out of every 24. Cotton-top tamarins sleep around 13. Three-striped night monkeys are technically nocturnal, though really, they’re hardly ever awake — they sleep for 17 hours a day. Samson calls this discrepancy the human sleep paradox. “How is this possible, that we’re sleeping the least out of any primate?” he says. Sleep is known to be important for our memory, immune function and other aspects of health. A predictive model of primate sleep based on factors such as body mass, brain size and diet concluded that humans ought to sleep about 9.5 hours out of every 24, not seven. “Something weird is going on,” Samson says. Research by Samson and others in primates and non-industrial human populations has revealed the various ways that human sleep is unusual. We spend fewer hours asleep than our nearest relatives, and more of our night in the phase of sleep known as rapid eye movement, or REM. The reasons for our strange sleep habits are still up for debate but can likely be found in the story of how we became human. Graph shows average time spent sleep of different primate species. Humans sleep the least at seven hours per night; the three-striped night monkey sleeps the most at nearly 17 hours. © 2022 Annual Reviews

Keyword: Sleep; Evolution
Link ID: 28310 - Posted: 04.30.2022

By Michele Lent Hirsch Sleep problems are a hallmark of modern American life — perhaps never more so than recently. In 2016, the Centers for Disease Control and Prevention found that a third of Americans were getting too little sleep at night. But then came the stressors of the pandemic, job losses, disrupted schedules and closed schools, which kept record numbers of Americans up at night or unable to wake up in the morning. As many as 2 in 3 Americans reported getting either too much or too little sleep, in a survey from the American Psychological Association during the pandemic’s second year. And the insomnia of the past two years may be stubbornly hanging on: Many people continue having more trouble falling asleep or staying asleep or have seen unusual shifts in their sleep schedules. All of this is taking a toll. “These different types of sleep changes seem to be closely related to [problems with] mental health,” says Karianne Dion, a graduate student in clinical psychology at the University of Ottawa. Research she co-wrote, published in the Journal of Sleep Research in 2021, found “worse symptoms of stress, anxiety, and depression” among those who are sleeping less or going to bed later and waking up later than before. Researchers have long known that anxiety and depression can lead to sleeplessness, while sleeping poorly can increase the likelihood of anxiety and depression. But a good night’s rest is also critical for a strong immune system, as well as for health overall. Insufficient sleep over time is associated with a greater risk of diabetes, high blood pressure and heart disease, according to the CDC. It can lead to memory and cognitive issues as well. So how can we get the sleep we need? Here’s how to solve seven common problems that can interfere with your rest and your health. © 1996-2022 The Washington Post

Keyword: Sleep
Link ID: 28303 - Posted: 04.27.2022

Kayt Sukel Each night, as you transition into deep sleep from wakefulness, your body undergoes a remarkable transformation. Your muscles relax. Your breathing slows. Your temperature and blood pressure drop. Even your brain activity changes, decelerating into slow, coordinated waves. Despite these remarkable physiological changes, scientists are now learning that the brain is far from idle during sleep. Rather, it remains hard at work, facilitating memory and learning while uncoupled from the external world. “For a long time, we believed that being awake all day depleted you and that sleep was what was required to restore and reinvigorate the whole body, including the brain,” says Robert Stickgold, a pioneering sleep researcher at Harvard Medical School. “It turns out that rest has very little to do with the function of sleep—rather, our brain is sorting and consolidating the information we learned during the day so we can better access it when it’s needed.” Anyone who has ever pulled an all-nighter knows the effect that sleep deprivation can have on cognitive function, including one’s ability to learn and retain new information. Yet, over the last few decades, neuroscientists across the globe have learned that sleep plays an integral role in memory—and it is a role that is highly conserved across the animal kingdom. To better understand how sleep helps us remember, these researchers have been working to characterize not only the physiological changes observed during sleep, but also the neural mechanisms underlying them. Nearly every animal on earth, from fruit flies to non-human primates, experiences some form of sleep, a naturally recurring state of altered consciousness and inhibited sensory activity. And while the exact amount of time spent in slumber, and the patterns of neural activity, differ from animal to animal, humans are no different. We need sleep to thrive. © 2022 The Dana Foundation.

Keyword: Sleep; Learning & Memory
Link ID: 28285 - Posted: 04.16.2022

Yue Leng Doctors often recommend “power naps” as a way to compensate for a poor night’s sleep and help keep alert until bedtime. But for older adults, extensive power naps could be an early sign of dementia. Research on how napping affects cognition in adults has had mixed results. Some studies on younger adults suggest that napping is beneficial to cognition, while others on older adults suggest it may be linked to cognitive impairment. However, many studies are based on just a single self-reported nap assessment. This methodology may not be accurate for people with cognitive impairment who may not be able to reliably report when or how long they napped. As an epidemiologist who studies sleep and neurodegeneration in older adults, I wanted to find out if changes in napping habits foreshadow other signs of cognitive decline. A study my colleagues and I recently published found that while napping does increase with age, excessive napping may foreshadow cognitive decline. Sleep may play a significant role in Alzheimer’s development. The link between daytime napping and dementia Sleep disturbance and daytime napping are known symptoms of mild to moderate Alzheimer’s disease and other forms of dementia in older adults. They often become more extreme as the disease progresses: Patients are increasingly less likely to fall asleep and more likely to wake up during the night and feel sleepy during the day. © 2010–2022, The Conversation US, Inc.

Keyword: Alzheimers; Sleep
Link ID: 28256 - Posted: 03.30.2022

By Erin Blakemore From the streetlights outside our bedrooms to the lamps and devices inside, sleeping with some amount of light has become a way of life for many. That may not be such a bright idea. Research suggests that sleeping in a moderately lit room could affect metabolic and cardiovascular health compared with snoozing in a room with dimmer light. We don’t need more sleep. We just need more darkness. In a study published in PNAS, researchers at Northwestern University had two groups of 10 young adults sleep in differently lit rooms. One group slept in rooms with dim light for two nights; the other slept one night in a room with dim night and the next in a room with moderate overhead light — about the equivalent of an overcast day. Participants wore heart monitors at night. In the morning, they did a variety of glucose tests. Both groups got the same amount of sleep but their bodies experienced very different nights. Both groups responded well to insulin the first night, when they both slept in dim lighting. On the second night, however, the group sleeping in brighter lighting didn’t respond as well to insulin. The dim light sleepers’ insulin resistance scores fell about 4 percent on the second night, while the bright sleepers’ rose about 15 percent. Their heart rates were faster on the bright night, too. The heightened heart rate and other measures led the researchers to conclude that light activates the sympathetic nervous system, which usually dominates bodily functions during the day.

Keyword: Sleep; Biological Rhythms
Link ID: 28252 - Posted: 03.26.2022

Hannah Devlin Science corespondent Taking long naps could be a precursor of Alzheimer’s disease, according to a study that tracked the daytime sleeping habits of elderly people. The findings could help resolve the conflicting results of the effects of napping on cognition in older adults, with some previous studies highlighting the benefits of a siesta on mood, alertness and performance on mental tasks. The latest study suggests that an increase over time in naps was linked to a higher chance of developing mild cognitive impairment or Alzheimer’s. The scientists think it is more likely that excessive napping could be an early warning sign, rather than it causing mental decline. “It might be a signal of accelerated ageing,” said Dr Yue Leng, an assistant professor of psychiatry at the University of California San Francisco. “The main takeaway is if you didn’t used to take naps and you notice you’re starting to get more sleepy in the day, it might be a signal of declining cognitive health.” The scientists tracked more than 1,000 people, with an average age of 81, over several years. Each year, the participants wore a watch-like device to track mobility for up to 14 days. Each prolonged period of non-activity from 9am to 7pm was interpreted as a nap. The participants also underwent tests to evaluate cognition each year. At the start of the study 76% of participants had no cognitive impairment, 20% had mild cognitive impairment and 4% had Alzheimer’s disease. For participants who did not develop cognitive impairment, daily daytime napping increased by an average 11 minutes a year. The rate of increase doubled after a diagnosis of mild cognitive impairment to a total of 24 minutes and nearly tripled to a total of 68 minutes after a diagnosis of Alzheimer’s disease, according to the research published in the journal Alzheimer’s and dementia. © 2022 Guardian News & Media Limited

Keyword: Alzheimers; Sleep
Link ID: 28244 - Posted: 03.19.2022

By Veronique Greenwood Sharks are celebrated for their apparently ceaseless motion — a small handful of species such as great white sharks must even swim to breathe, keeping water washing over their gills. Still, all that moving doesn’t preclude sharks from having a rest. Sleep across the animal kingdom manifests itself in many peculiar ways, like the birds whose brains sleep one half at a time or the bats that spend almost every hour of their day snoozing. And in a paper published in Current Biology on Wednesday, researchers confirmed that the draughtsboard shark, a small nocturnal shark native to New Zealand, appears to be sleeping during periods of calm, reporting that their metabolism and posture change significantly during these bouts of repose. They do, however, in a creepy touch, keep their eyes open for a lot of it. Further research will be required to demonstrate that other kinds of sharks catch underwater z’s like the draughtsboard shark. But the new study supports the hypothesis that one reason organisms might have evolved sleep is as a tool for conserving energy. Draughtsboard sharks were identified last year as sleepers by this same group of researchers based in New Zealand and Australia. They watched captured sharks carefully in tanks and tested their responses to disturbances during their restful periods. (These sharks are not among those that swim to breathe; they hang out on the ocean floor and pump water over their gills.) The team found that it was more difficult to prompt the sharks into movement if they had been still for a long time, suggesting they were in fact sleeping. This time, said Craig Radford, a professor of marine science at the University of Auckland and an author of the new paper, the researchers were looking to compare the sharks’ metabolisms during these periods of calm, defined as being still for longer than five minutes, with when they were resting for shorter periods and when they were actively swimming. They used a specially built tank with instruments that let them monitor how much oxygen the sharks were using, a way to indirectly measure metabolism. Seven sharks each spent 24 hours in the tank, and the researchers found that these states were indeed quite different. © 2022 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 28234 - Posted: 03.11.2022

ByKelly Servick In 1997, Laura Gould put her 15-month-old daughter, Maria, down for a nap and returned to find her unresponsive. She had died suddenly, with no clues to explain the tragedy besides a fever the night before. When her daughter’s body was sent to the medical examiner’s office, “I thought they’d call me in an hour and tell me what happened … like on TV,” Gould says. Months later, neither that office nor independent pathologists had an explanation. “I hated ending it with ‘the autopsy was inconclusive, go on and live your life now,’” she says. “It just didn’t really feel like that was an option.” Gould co-founded a nonprofit foundation to support grieving parents, raise research funds, and increase awareness of sudden unexplained death in childhood (SUDC), a term used for children older than 12 months. In the United States, roughly 400 deaths fall into this category each year—about one-quarter as many as are labeled sudden infant death syndrome (SIDS). Two recent genetic analyses, one funded in part by Gould’s SUDC Foundation, now suggest potential causes for at least a small fraction of cases: mutations in genes associated with epilepsy, heart arrhythmias, and neurodevelopmental disorders. “Having this data is important,” says Marco Hefti, a neuropathologist at the University of Iowa Carver College of Medicine who was not involved in the new studies. SUDC is not a single disease, but “a grab bag of different things—and the more of those different things you can pull out, the better for everybody.” Neither study can say with certainty that a mutation is responsible for a child’s death. But the findings provide a basis for animal studies that could reveal how the genetic changes interfere with vital functions. They might also inform future child death investigations and potentially even screening programs to prevent deaths. Research on SUDC has lagged that on the more common and better known SIDS. Yet, biologically, SIDS and SUDC “may be part of a spectrum,” says Ingrid Holm, a medical geneticist at Boston Children’s Hospital. In both, death often occurs during sleep, and researchers suspect contributors including undetected heart defects, metabolic disorders, and central nervous system abnormalities. The children who die are roughly 10 times more likely than the average child to have a history of febrile seizures—convulsions that come with fevers in young children, notes neurologist Orrin Devinsky of New York University (NYU) Langone Health. © 2022 American Association for the Advancement of Science.

Keyword: Sleep; Genes & Behavior
Link ID: 28200 - Posted: 02.12.2022

Ian Sample Science editor People who develop Alzheimer’s disease can experience sleep disturbances years before the condition takes hold, but whether one causes the other, or something more complex is afoot, has always proved hard for scientists to determine. Now, researchers in the US have shed light on the mystery, in work that raises hopes for new therapies, and how “good sleep hygiene” could help to tackle the disease and its symptoms. The findings show that humans’ 24-hour circadian clock controls the brain’s ability to mop up wayward proteins linked to Alzheimer’s disease. If the scientists are right, the work would explain, at least in part, how disruption to circadian rhythms and sleep disturbances might feed into the onset and progression of Alzheimer’s disease, and how preventing such disruption might stave off the condition. “Circadian disruption is correlated with Alzheimer’s diagnosis and it has been suggested that sleep disruptions could be an early warning sign of Alzheimer’s disease,” said Dr Jennifer Hurley, who led the research at Rensselaer Polytechnic Institute, in New York. Alzheimer’s takes hold when connections are lost between nerve cells in the brain. The disease is progressive and linked to abnormal plaques and tangles of proteins that steadily build up in the brain. The disease is the most common cause of dementia and affects more than half a million people in the UK, a figure that is set to rise. To keep the brain healthy, immune cells called microglia seek out and destroy troublesome proteins that threaten to accumulate in the brain. One type of protein targeted by the cells is called amyloid beta, a hallmark of Alzheimer’s. © 2022 Guardian News & Media Limited

Keyword: Alzheimers; Sleep
Link ID: 28197 - Posted: 02.12.2022

Ian Sample Science editor Getting an hour or so more sleep each night can help people to cut calories, according a small clinical trial in overweight adults. Researchers in the US found that people who typically slept for less than 6.5 hours a night shed an average of 270 calories from their daily intake when they got an extra 1.2 hours of sleep. Sustained over three years, the reduction in calories could lead people to lose about 12kg (26lbs) without changing their diet during the day, the scientists believe. Some participants in the study consumed 500 fewer calories a day after improving their sleep. The study was not designed to look at weight loss, but researchers noticed the fall in calories within two weeks of patients changing their sleep patterns. “If healthy sleep habits are maintained over longer duration, this would lead to clinically important weight loss over time,” said Dr Esra Tasali, of the University of Chicago’s sleep centre. “Many people are working hard to find ways to decrease their caloric intake to lose weight – well, just by sleeping more, you may be able to reduce it substantially.” The trial studied 80 adults aged 21 to 40 with a body mass index between 25 and 29.9, meaning they were overweight. Half of the participants were randomly assigned to receive personalised sleep hygiene counselling aimed at extending the amount of time they slept each night. © 2022 Guardian News & Media Limited

Keyword: Sleep; Obesity
Link ID: 28191 - Posted: 02.09.2022

By Amelia Nierenberg A couple of glasses of wine or a few drinks in the evening will probably make you fall asleep faster than normal. Who among us hasn’t left the dishes for the next morning or neglected a skin-care routine after a dinner party or festive night out? But even if you thud into dreamland, there’s a good chance that too much alcohol will mean a fitful night of sleep. That’s because alcohol disrupts what’s known as your sleep architecture, the normal phases of deeper and lighter sleep we go through every night. A night of drinking can “fragment,” or interrupt, these patterns, experts say, and you may wake up several times as you ricochet through the usual stages of sleep. “You pay for it in the second half of the night,” said Dr. Jennifer Martin, a psychologist and professor of medicine at the University of California, Los Angeles. Alcohol is “initially sedating, but as it’s metabolized, it’s very activating.” Here’s how it breaks down. In the first half of the night, when fairly high levels of alcohol are still coursing through your bloodstream, you’ll probably sleep deeply and dreamlessly. One reason: In the brain, alcohol acts on gamma-aminobutyric acid, or GABA, a neurotransmitter that inhibits impulses between nerve cells and has a calming effect. Alcohol can also suppress rapid eye movement, or REM sleep, which is when most dreaming occurs. Later in the night, as alcohol levels drop, your brain kicks into overdrive. You may toss and turn as your body undergoes a rebound arousal. “As the levels decline, you’re going to get more issues with the fragmentation,” said Dr. R. Nisha Aurora, a member of the board of directors of the American Academy of Sleep Medicine. You’ll also probably have more vivid or stressful dreams and — because fitful sleep means that you’re waking up more regularly — you are more likely to remember them.

Keyword: Sleep; Drug Abuse
Link ID: 28183 - Posted: 02.02.2022

By Amelia Nierenberg Most people think of melatonin as a natural nod-off aid, kind of like chamomile tea in pill form. Even the name of the popular dietary supplement sounds sleepy — that long “o” sound almost makes you yawn mid-word. But melatonin is also a hormone that our brains naturally produce, and hormones, even in minuscule amounts, can have potent effects throughout the body. “There are some clinical uses for it, but not the way that it’s marketed and used by the vast majority of the general public,” said Jennifer Martin, a psychologist and professor of medicine at the University of California, Los Angeles. Experts strongly urge people to consult their doctor or a sleep specialist before taking melatonin, in part because the supplement does not address many underlying health problems that may be disrupting sleep. Anxiety can cause insomnia, as can a host of other potentially serious ailments, such as sleep apnea, restless legs syndrome or mood disorders like depression, that may require medical treatment. Melatonin, however, is relatively inexpensive and readily available at local pharmacies in the United States (in other countries it typically requires a prescription), and many people will go out and buy it on their own. So what’s the best approach to taking melatonin? Here’s what experts had to say. During the day, the brain’s pea-sized pineal gland remains inactive. A few hours before our natural sleep time, as it starts to get dark outside and the light entering our retina fades, the gland switches on to flood the brain with melatonin. “Melatonin is sometimes called the ‘hormone of darkness’ or ‘vampire hormone,’” because it comes out at night, said Matthew Walker, a professor of neuroscience and psychology at the University of California, Berkeley, and the author of the book “Why We Sleep.” As levels of melatonin rise, levels of cortisol, the stress hormone, fall. Respiration slows. Soon, our eyelids begin to droop. Instead of a lights-out trigger, melatonin acts more like a dimmer switch, turning the day functions off and switching night functions on. So taking a melatonin supplement is sort of like taking a dose of sunset, tricking your body into feeling like it’s nighttime. It doesn’t put you to sleep as much as it tells the body that it’s time to sleep. © 2022 The New York Times Company

Keyword: Biological Rhythms; Sleep
Link ID: 28158 - Posted: 01.19.2022

Leyland Cecco A whistleblower in the Canadian province of New Brunswick has warned that a progressive neurological illness that has baffled experts for more than two years appears to be affecting a growing number of young people and causing swift cognitive decline among some of the afflicted. Speaking to the Guardian, an employee with Vitalité Health Network, one of the province’s two health authorities, said that suspected cases are growing in number and that young adults with no prior health triggers are developing a catalog of troubling symptoms, including rapid weight loss, insomnia, hallucinations, difficulty thinking and limited mobility. The official number of cases under investigation, 48, remains unchanged since it was first announced in early spring 2021. But multiple sources say the cluster could now be as many as 150 people, with a backlog of cases involving young people still requiring further assessment. “I’m truly concerned about these cases because they seem to evolve so fast,” said the source. “I’m worried for them and we owe them some kind of explanation.” At the same time, at least nine cases have been recorded in which two people in close contact – but without genetic links – have developed symptoms, suggesting that environmental factors may be involved. One suspected case involved a man who was developing symptoms of dementia and ataxia. His wife, who was his caregiver, suddenly began losing sleep and experiencing muscle wasting, dementia and hallucinations. Now her condition is worse than his. A woman in her 30s was described as non-verbal, is feeding with a tube and drools excessively. Her caregiver, a nursing student in her 20s, also recently started showing symptoms of neurological decline. © 2021 Guardian News & Media Limited

Keyword: Movement Disorders; Alzheimers
Link ID: 28140 - Posted: 01.05.2022

By Christina Caron Q: Sometimes my eyelid twitches on and off for days — weeks, even. It’s distracting and irritating. How do I get it to stop? And should I be concerned? Eyelid spasms, while annoying, are “rarely a sign of something serious,” said Stephanie Erwin, an optometrist at Cleveland Clinic’s Cole Eye Institute. The most common type of eye twitch is a series of muscle contractions called eyelid myokymia, which produces involuntary and intermittent contractions of the eyelid, typically the lower one. Only one eye is affected at a time because the twitch originates in the muscle surrounding the eye, and not the nerve that controls the blink reflex, which sends the same message to both eyes simultaneously, Dr. Erwin added. The spasms can last from hours to days to months. “If the twitching persists for a long period of time, or is accompanied by additional symptoms, it is a good idea to be checked by an eye doctor to make sure nothing else is going on,” she said. If the twitching spreads to other muscles in the face or if you notice both eyes are twitching at the same time, those are indications of a more serious problem. Other red flags include a drooping eyelid or a red eye. But if just one eyelid is twitching on and off, it is usually a harmless (and often exasperating) case of eyelid myokymia. As for why it happens: “Nobody knows exactly why,” said Dr. Alice Lorch, an ophthalmologist at Massachusetts Eye and Ear in Boston. But more commonly, it is stress, lack of sleep or excessive caffeine intake that brings on eyelid twitching, the experts said. Dry eye, a common affliction among those who stare at screens most of the day, is another culprit. Studies have indicated that we blink less when looking at digital devices, which makes our eyes feel dry. © 2021 The New York Times Company

Keyword: Vision; Stress
Link ID: 28131 - Posted: 12.31.2021

By Linda Searing Among people who have covid-19, those who have certain sleep disorders (including sleep apnea) face a 31 percent greater chance of developing a severe case that requires hospitalization, or dying from the disease, than do people who have covid-19 and who do not have sleep-disturbed breathing, according to research published in The study links the increase in risk to breathing disorders that can cause oxygen levels to drop during sleep, creating a low oxygen level called hypoxia. The researchers found that having such a sleep-related breathing disorder did not make people more likely to contract the coronavirus. They wrote, however, that having low oxygen levels “may play a role in worse outcomes once the viral illness evolves,” describing hypoxia as an “amplifier” of covid effects. The findings were based on data from 5,402 adults (average age 56) who had undergone sleep studies and coronavirus testing in 2020 through the Cleveland Clinic Health System. For someone with sleep apnea, which is one of the most common sleep disorders, breathing repeatedly stops and starts during sleep, sometimes 30 times or more an hour and often is accompanied by gasping or snorting sounds. This causes hypoxia. Treatment often involves using what is called positive airway pressure (PAP) while sleeping. The person wears a mask, which has a tube connected to a small PAP machine that sits bedside. It pumps pressurized air into the upper airway, keeping it open and allowing normal breathing. The researchers suggested further studies to determine whether such treatment would improve covid-19 outcomes for people with a sleep disorder. © 1996-2021 The Washington Post

Keyword: Sleep
Link ID: 28126 - Posted: 12.29.2021

By Richard Sandomir Allan Rechtschaffen, an indefatigable sleep researcher at the University of Chicago who tested the effects of sleep deprivation, studied dreaming, narcolepsy, napping and insomnia and standardized the measurement of sleep stages, died on Nov. 29 at his home in Chicago. He was 93. His wife, Karen Rechtschaffen, confirmed the death. The University of Chicago was an established center of sleep research when Professor Rechtschaffen arrived on its campus in 1957 as a psychology instructor. Four years earlier, Nathaniel Kleitman, a physiologist, and Eugene Aserinsky, a graduate student, had written a paper that reported the discovery of rapid eye movement, or REM, during sleep, an indication of dreaming. The finding appealed to Professor Rechtschaffen’s fascination with the mind’s effect on the body. “This was a perfect vehicle for studying that issue,” he said in an interview in 2010 with the Sleep Research Society, which he helped start 50 years earlier. “You could conceive of it as the mind turning on with the REM period and turning off with the end of the REM period. So you could see periods of mind and periods of no mind.” REM and other aspects of sleep became the focus of his career. In 1958, he was named director of the university’s sleep research laboratory, where his experiments on animals and humans over the next 41 years helped him define a challenge that he described this way: “If sleep doesn’t serve an absolutely vital function, it is the biggest mistake evolution ever made.” His best-known experiment concerned self-deprivation using rats. As Professor Rechtschaffen and his colleagues reported in the journal Science in 1983, they had placed two rats at a time in a plexiglass box, each with an electrode attached from its head to a computer and each placed on one-half of a divided disk built over shallow water. When the experimental rat tried to sleep, the disk automatically rotated, forcing the animal to stay awake. The control rat was treated similarly but could sleep when the other rat was awake and the disk was not moving. © 2021 The New York Times Company

Keyword: Sleep
Link ID: 28116 - Posted: 12.18.2021

Sofia Moutinho When Thomas Edison hit a wall with his inventions, he would nap in an armchair while holding a steel ball. As he started to fall asleep and his muscles relaxed, the ball would strike the floor, waking him with insights into his problems. Or so the story goes. Now, more than 100 years later, scientists have repeated the trick in a lab, revealing that the famous inventor was on to something. People following his recipe tripled their chances of solving a math problem. The trick was to wake up in the transition between sleep and wakefulness, just before deep sleep. “It is a wonderful study,” says Ken Paller, a cognitive neuroscientist at Northwestern University who was not part of the research. Prior work has shown that passing through deep sleep stages helps with creativity, he notes, but this is the first to explore in detail the sleep-onset period and its role in problem-solving. In this transitional period, we are not quite awake, but also not deeply asleep. It can be as short as a minute and occurs right when we start to doze off. Our muscles relax, and we have dreamlike visions or thoughts called hypnagogia, generally related to recent experiences. This phase slips by unnoticed most of the time unless it is interrupted by waking. Like Edison, surrealist painter Salvador Dalí believed interrupting sleep’s onset could boost creativity. (He used a heavy key instead of a metal ball.) To see whether Dalí and Edison were right, researchers recruited more than 100 easy sleepers. The team gave them a math test that required them to convert strings of eight digits into new strings of seven by using specific rules in a stepwise manner, such as “repeat the number if the previous and next digit are identical.” The volunteers weren’t told that there was an easier way to get the right answers by following a hidden rule: The second number in their final string was always the same as the last number in the same string. © 2021 American Association for the Advancement of Science.

Keyword: Sleep; Attention
Link ID: 28106 - Posted: 12.11.2021

Sophie Fessl Catching some z’s repairs a day’s damage to neurons’ DNA, at least in zebrafish. While the fish are awake, DNA damage accumulates, which, through a buildup of the DNA repair protein Parp1, triggers sleep, according to a study published today (November 18) in Molecular Cell. The study is “pivotal in providing evidence regarding sleep and its role in DNA damage and repair,” writes anesthesiologist Siu Wai Choi of the University of Hong Kong in an email to The Scientist. Choi led an earlier study that established a link between sleep deprivation and DNA damage in doctors but was not involved in the current research. Cells routinely face stress, such as exposure to radiation, that can leave their DNA damaged. Cells therefore have an arsenal of repair proteins to mend the DNA or, if it’s irreparable, trigger cell death. Neuroscientist Lior Appelbaum and his team at Bar-Ilan University in Israel had previously found that DNA damage increases during the day and decreases during the night, suggesting that sleep could help repair this damage. In the new study, they investigated whether DNA damage is the reason why zebrafish—and, by extension, perhaps other animals—sleep. When postdoc David Zada and other authors induced DNA damage in the neurons of zebrafish larvae by inducing neuronal activity or using UV radiation, the fish slept longer. “It makes the fish tired,” says Appelbaum. © 1986–2021 The Scientist.

Keyword: Sleep; Genes & Behavior
Link ID: 28081 - Posted: 11.20.2021

David Robson Michelle Carr is frequently plagued by tidal waves in her dreams. What should be a terrifying nightmare, however, can quickly turn into a whimsical adventure – thanks to her ability to control her dreams. She can transform herself into a dolphin and swim into the water. Once, she transformed the wave itself, turning it into a giant snail with a huge shell. “It came right up to me – it was a really beautiful moment.” There’s a thriving online community of people who are now trying to learn how to lucid dream. (A single subreddit devoted to the phenomenon has more than 400,000 members.) Many are simply looking for entertainment. “It’s just so exciting and unbelievable to be in a lucid dream and to witness your mind creating this completely vivid simulation,” says Carr, who is a sleep researcher at the University of Rochester in New York state. Others hope that exercising skills in their dreams will increase their real-life abilities. “A lot of elite athletes use lucid dreams to practise their sport.” And there are more profound reasons to exploit this sleep state, besides personal improvement. By identifying the brain activity that gives rise to the heightened awareness and sense of agency in lucid dreams, neuroscientists and psychologists hope to answer fundamental questions about the nature of human consciousness, including our apparently unique capacity for self-awareness. “More and more researchers, from many different fields, have started to incorporate lucid dreams in their research,” says Carr. This interest in lucid dreaming has been growing in fits and starts for more than a century. Despite his fascination with the interaction between the conscious and subconscious minds, Sigmund Freud barely mentioned lucid dreams in his writings. Instead, it was an English aristocrat and writer, Mary Arnold-Forster, who provided one of the earliest and most detailed descriptions in the English language in her book Studies in Dreams. © 2021 Guardian News & Media Limited

Keyword: Sleep; Consciousness
Link ID: 28079 - Posted: 11.17.2021

Clare Marie Schneider For some people, waking up early just feels natural. Carla Finley is a baker in Brooklyn, N.Y., who starts her day at 5 or 6 a.m. Finley is what we would call a morning person. "Sometimes it's still dark, which actually I love," she says. "Something about feeling the light come in feels really sacred." This story comes from Life Kit, NPR's family of podcasts to help make life better — covering everything from exercise to raising kids to making friends. For more, sign up for the newsletter and follow @NPRLifeKit on Twitter. Of course, not everyone is as lucky as Finley. Emily Gerard is a writer for the Today show, and she often finds herself waking up at odd hours to prepare for the show, which starts at 7 a.m. "When that alarm goes off, I have a few moments of feeling like I want to die," she says. There are a lot of reasons why we may have to get up early. Maybe it's for work, or maybe it's to get your kids ready for school or take care of a family member. Maybe you just want some time to work on your hobby or take care of errands before a busy day. But if you're not naturally a morning person, how much room do you have to change your wake-up schedule? "We have a fair amount of wiggle room, but it's behavioral," says Dr. Katie Sharkey, an associate professor of medicine and psychiatry and human behavior at Brown University's Alpert Medical School. Basically, your biological clock, which determines your circadian rhythms, is baked into who you are to an extent, but a few habits can help make waking up earlier less of a chore. © 2021 npr

Keyword: Biological Rhythms
Link ID: 28063 - Posted: 11.06.2021