Chapter 14. Biological Rhythms, Sleep, and Dreaming

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/ By Richard G ‘Bugs’ Stevens Light pollution is often characterized as a soft issue in environmentalism. This perception needs to change. Light at night constitutes a massive assault on the ecology of the planet, including us. It also has indirect impacts because, while 20 percent of electricity is used for lighting worldwide, at least 30 percent of that light is wasted. Wasted light serves no purpose at all, and excessive lighting is too often used beyond what is needed for driving, or shopping, or Friday-night football. It might be that virtually all aspects of health and wellbeing are dependent to one extent or another on a synchronized circadian rhythmicity, with a natural cycle of bright days and dark nights. The electric light bulb is touted as one of the most significant technological advancements of human beings. It ranks right up there with the wheel, control of fire, antibiotics, and dynamite. But as with any new and spectacular technology, there are invariably unintended consequences. With electric light has come an obliteration of night in much of the modern world; both outside in the city, and indoors during what was once ‘night’ according to the natural position of the sun. Life has evolved for several billion years with a reliable cycle of bright light from the sun during the day, and darkness at night. This has led to the development of an innate circadian rhythm in our physiology; that circadian rhythm depends on the solar cycle of night and day to maintain its precision. During the night, beginning at about sunset, body temperature drops, metabolism slows, hunger abates, sleepiness increases, and the hormone melatonin rises dramatically in the blood. This natural physiological transition to night is of ancient origin, and melatonin is crucial for the transition to proceed as it should. Copyright 2018 Undark

Keyword: Biological Rhythms
Link ID: 25345 - Posted: 08.17.2018

By Jane E. Brody Attention all you happy high school graduates about to go off to college, as well as the many others returning for another year of higher education. Grandsons Stefan and Tomas, that includes you. Whatever you may think can get in the way of a successful college experience, chances are you won’t think of one of the most important factors: how long and how well you sleep. And not just on weekends, but every day, Monday through Sunday. Studies have shown that sleep quantity and sleep quality equal or outrank such popular campus concerns as alcohol and drug use in predicting student grades and a student’s chances of graduating. Although in one survey 60 percent of students said they wanted information from their colleges on how to manage sleep problems, few institutions of higher learning do anything to counter the devastating effects of sleep deprivation on academic success and physical and emotional well-being. Some, in fact, do just the opposite, for example, providing 24-hour library hours that encourage students to pull all-nighters. (I did that only once, to study for an exam in freshman year, and fell asleep in the middle of the test. Lesson well learned!) An all-nighter may help if all you have to do is memorize a list, but if you have to do something complex with the information, you’ll do worse by staying up all night, J. Roxanne Prichard, an expert on college sleep issues, told me. After being awake 16 hours in a row, brain function starts to decline, and after 20 hours awake, you perform as if legally drunk, she said. Many college-bound kids start out with dreadful sleep habits that are likely to get worse once the rigorous demands of college courses and competing social and athletic activities kick in. © 2018 The New York Times Company

Keyword: Sleep; Learning & Memory
Link ID: 25324 - Posted: 08.13.2018

Sleeping longer than the recommended seven or eight hours a night has been linked with a higher risk of premature death, according to new research. Researchers looked at data from 74 studies involving more than three million people and found those who slept for 10 hours were 30% more likely to die prematurely than those who slept for eight. Staying in bed for more than 10 hours was also linked to a 56% increased risk of death from stroke and a 49% increased risk of death from cardiovascular disease. Poor sleep quality was associated with a 44% increase in risk of coronary heart disease, according to the study published in the Journal of the American Heart Association. Researchers said their study suggests abnormal sleep could be “a marker of elevated cardiovascular risk” and said GPs ought to ask questions about sleeping patterns during appointments. Lead researcher Dr Chun Shing Kwok, of Keele University’s Institute for Science and Technology in Medicine, said: “Abnormal sleep is a marker of elevated cardiovascular risk and greater consideration should be given in exploring both duration and sleep quality during patient consultations. “There are cultural, social, psychological, behavioural, pathophysiological and environmental influences on our sleep such as the need to care for children or family members, irregular working shift patterns, physical or mental illness, and the 24-hour availability of commodities in modern society.” © 2018 Guardian News and Media Limited

Keyword: Sleep
Link ID: 25302 - Posted: 08.07.2018

By Alex Marshall Alan Alda has been living with Parkinson’s disease for over three years, the actor revealed Tuesday in an appearance on CBS’s “This Morning.” “The reason I want to talk about it in public is that I was diagnosed three-and-a-half years ago, and I’ve had a full life since,” he said. “I thought it’s probably only a matter of time before somebody does a story about this from a sad point of view,” he added, pointing out that one of his thumbs had been twitching in recent TV appearances. “But that’s not where I am.” Parkinson’s is a movement disorder with symptoms that include muscle tremors and stiffness, poor balance and coordination. It affects over a million Americans, according to the American Parkinson Disease Association, including Michael J. Fox and the Rev. Jesse L. Jackson, the longtime civil rights leader. Mr. Alda, who made his name in the TV series “M*A*S*H,” said he went to the doctors after reading an article in The New York Times, by Jane E. Brody, which said that acting out one’s dreams could be an early warning sign of the disorder. “By acting out your dreams, I mean I was having a dream that somebody was attacking me and I threw a sack of potatoes at them,” Mr. Alda, 82, said in the interview. “But what I was really doing is throwing a pillow at my wife.” He said he had no other symptoms, but a few months later noticed a thumb twitch. Mr. Alda said he was also speaking out to reassure people that they do not have to be fearful after a diagnosis. “You still have things you can do,” he said. Mr. Alda goes boxing three times a week, plays tennis and marches to John Philip Sousa music. “Marching to march music is good for Parkinson’s,” he explained. Mr. Alda was not trying to belittle people who have severe symptoms, he added. “That’s difficult,” he said. © 2018 The New York Times Company

Keyword: Parkinsons; Sleep
Link ID: 25277 - Posted: 08.01.2018

By Anahad O’Connor Nutrition scientists have long debated the best diet for optimal health. But now some experts believe that it’s not just what we eat that’s critical for good health, but when we eat it. A growing body of research suggests that our bodies function optimally when we align our eating patterns with our circadian rhythms, the innate 24-hour cycles that tell our bodies when to wake up, when to eat and when to fall asleep. Studies show that chronically disrupting this rhythm — by eating late meals or nibbling on midnight snacks, for example — could be a recipe for weight gain and metabolic trouble. That is the premise of a new book, “The Circadian Code,” by Satchin Panda, a professor at the Salk Institute and an expert on circadian rhythms research. Dr. Panda argues that people improve their metabolic health when they eat their meals in a daily 8- to 10-hour window, taking their first bite of food in the morning and their last bite early in the evening. This approach, known as early time-restricted feeding, stems from the idea that human metabolism follows a daily rhythm, with our hormones, enzymes and digestive systems primed for food intake in the morning and afternoon. Many people, however, snack and graze from roughly the time they wake up until shortly before they go to bed. Dr. Panda has found in his research that the average person eats over a 15-hour or longer period each day, starting with something like milk and coffee shortly after rising and ending with a glass of wine, a late night meal or a handful of chips, nuts or some other snack shortly before bed. That pattern of eating, he says, conflicts with our biological rhythms. Scientists have long known that the human body has a master clock in the brain, located in the hypothalamus, that governs our sleep-wake cycles in response to bright light exposure. A couple of decades ago, researchers discovered that there is not just one clock in the body but a collection of them. Every organ has an internal clock that governs its daily cycle of activity. © 2018 The New York Times Company

Keyword: Biological Rhythms; Obesity
Link ID: 25246 - Posted: 07.25.2018

By Frankie Schembri Do you ever find yourself scouring the web for pizza delivery services to satisfy those late-night cravings? You’re not alone: A new study reveals that hungry web surfers around the world all start searching for food-related information at two peak times, 7 p.m. and 2 a.m. Wanting to see if they could spot trends in human behavior based on a massive database of Google searches, a team of scientists analyzed hourly food-related queries from five countries: the United States, Canada, India, Australia, and the United Kingdom. For two 1-week periods, they looked for general food-related keywords such as “pizza delivery” or “Chinese delivery” and country-specific delivery companies like India’s “Swiggy” and “Just Eat,” which serves the United Kingdom and Australia. They also analyzed 5 years of data to see if they could discover seasonal trends. The two spikes in food-related searches occurred across all countries, keywords, days of the week, and seasons, the researchers report today in Royal Society Open Science. They say the peaks likely represent two different groups of people searching for nighttime nourishment, one older (the early birds) and one younger (the night owls). Another hypothesis is that the two groups are simply running on different internal body clocks, which affects when they want their evening calories. © 2018 American Association for the Advancement of Science.

Keyword: Obesity; Biological Rhythms
Link ID: 25245 - Posted: 07.25.2018

By Dana G. Smith Suicide rates and temperatures are both on the rise, but are these two occurrences connected? A new study suggests maybe so. The research revealed hotter-than-average months corresponded to more deaths by suicide—and the effect isn’t limited to the summer, even warmer winters show the trend. In the study, published in Nature Climate Change, the investigators looked at all of the suicides that occurred in the U.S. and Mexico over several decades (1968 to 2004 for the U.S. and 1990 to 2010 for Mexico), comprising 851,088 and 611,366 deaths, respectively. They then observed how monthly temperature fluctuations over these periods in every county or municipality in both countries correlated to the suicide rates for that region. They discovered that for every 1-degree Celsius (1.8-degree Fahrenheit) rise in temperature, there was a 0.7 percent increase in suicide rates in the U.S. and a 2.1 percent increase in Mexico, averaging a 1.4 percent increment across both countries. That is, over the years, a given county would see more deaths by suicide in warmer-than-average months. Notably, the average temperature of the county did not matter; for example, Dallas and Minneapolis saw a similar rise in suicide rates. The effect did not depend on the month either—it made no difference whether it was January or July. There was also no difference between gender, socioeconomic status, access to guns, air-conditioning and whether it was an urban or rural region. Across the board, when temperatures rose in a given place, so did the number of suicides. © 2018 Scientific American

Keyword: Biological Rhythms; Depression
Link ID: 25243 - Posted: 07.24.2018

by Caroline Wellbery Jet lag can put the brakes on the most exciting vacations. Almost everyone who has ever flown across time zones knows what it feels like. The experience ranks somewhere between eating day-old cooked oatmeal and nursing a hangover. These food and drink metaphors aren’t just a coincidence. Jet lag, it turns out, affects more than our sleep; it affects our internal organs as well. Given what is known about the importance of intestinal bacteria (called the microbiome) and their connection to immune function and well-being, it’s clear that any discussion of jet lag, and how to deal with it, needs to consider “gut lag”as well. The issues begin with the fact that air travel across time zones disrupts our circadian rhythm — the human internal clock that evolved over millennia to match Earth’s 24-hour cycle of light and dark. One feature of this cycle is that maximum sleepiness coincides with a low point in core body temperature, which is usually unrelated to external temperatures. Core body temperature goes down as you sleep and is usually lowest two to three hours before waking (which also coincides with your deepest sleep). Low core body temperature appears to be a turning point in determining how sleepy or rested you feel, depending on when in the cycle you wake up. When you fly into a new time zone, your core body temperature doesn’t recognize that change and instead continues to dip according to the schedule of the place you have left. If you are awake or wake up before the dip, you are much more likely to feel groggy or out of sorts, especially if you are exposed to light while your body temperature drops. That’s because light and temperature signals come into conflict with each other: The light tells you that you’re wide-awake; the temperature signal tells you that you’re about to enter the deepest point in your sleep. This is when you will mostly strongly feel the unpleasant symptoms of jet lag. © 1996-2018 The Washington Post

Keyword: Biological Rhythms; Sleep
Link ID: 25236 - Posted: 07.23.2018

By Nicholas Bakalar A good night’s sleep may be critical for the metabolic health of teenagers. Researchers studied 829 boys and girls, average age 13, who wore electronic measuring devices that tracked sleep time, sleep quality and physical activity over seven to 10 days. They also recorded five factors associated with cardiovascular risk: waist circumference, blood pressure, HDL or “good” cholesterol, triglycerides and insulin resistance. Inadequate sleep was common — 31 percent of the children slept less than seven hours a night, and 58 percent had poor sleep efficiency as measured by percentage of time awake after initial sleep onset. Shorter sleep duration and poorer sleep efficiency were associated with higher systolic blood pressure, lower HDL cholesterol, higher triglycerides and higher glucose levels, all indicators of poorer metabolic health. Other studies have found that shorter sleep is associated with obesity, but in this study, published in Pediatrics, the associations were independent of body mass index. The researchers controlled for age and sex, race and ethnicity, TV viewing, fast food consumption and other factors. “It was surprising that we found that the relationship was not fully explained by body mass index,” said the lead author, Elizabeth M. Cespedes Feliciano, a staff scientist at Kaiser Permanente Northern California. “The main takeaway is that using objective measurements, we showed that both quantity and quality of sleep matter for metabolic health.” © 2018 The New York Times Compan

Keyword: Sleep; Development of the Brain
Link ID: 25219 - Posted: 07.18.2018

Laura Beil Neuroscientist Barbara Bendlin studies the brain as Alzheimer’s disease develops. When she goes home, she tries to leave her work in the lab. But one recent research project has crossed into her personal life: She now takes sleep much more seriously. Bendlin works at the University of Wisconsin–Madison, home to the Wisconsin Registry for Alzheimer’s Prevention, a study of more than 1,500 people who were ages 40 to 65 when they signed up. Members of the registry did not have symptoms of dementia when they volunteered, but more than 70 percent had a family history of Alzheimer’s disease. Since 2001, participants have been tested regularly for memory loss and other signs of the disease, such as the presence of amyloid-beta, a protein fragment that can clump into sticky plaques in the brain. Those plaques are a hallmark of Alzheimer’s, the most common form of dementia. Each person also fills out lengthy questionnaires about their lives in the hopes that one day the information will offer clues to the disease. Among the inquiries: How tired are you? Some answers to the sleep questions have been eye-opening. Bendlin and her colleagues identified 98 people from the registry who recorded their sleep quality and had brain scans. Those who slept badly — measured by such things as being tired during the day — tended to have more A-beta plaques visible on brain imaging, the researchers reported in 2015 in Neurobiology of Aging. |© Society for Science & the Public 2000 - 2018.

Keyword: Sleep; Alzheimers
Link ID: 25212 - Posted: 07.16.2018

Layal Liverpool Working night shifts can mess up the body’s natural rhythms so much that the brain and digestive system end up completely out of kilter with one another, scientists say. Three night shifts in a row had little impact on the body’s master clock in the brain, researchers found, but it played havoc with gut function, throwing the natural cycle out by a full 12 hours. The finding highlights the dramatic impact that night shifts can have on the different clocks that govern the natural rhythms of organs and systems throughout the human body. Internal disagreements over night and day may explain why people on night shifts, and those with jet lag, can suffer stomach pains and other gut problems, which clear up once their body has had time to adjust. “One of the first symptoms people experience when traveling across time zones is gastrointestinal discomfort and that’s because you knock their gut out of sync from their central biological clock,” said Hans Van Dongen, director of the Sleep and Performance Research Center at Washington State University. For the study, Van Dongen invited 14 healthy volunteers aged 22 to 34 into his sleep lab and split them into two groups. The first spent three days on a simulated day shift and could sleep from 10pm to 6am each night. Those in the second group stayed awake for three nights in a row and were only allowed to sleep from 10am to 6pm. © 2018 Guardian News and Media Limited

Keyword: Biological Rhythms; Obesity
Link ID: 25188 - Posted: 07.10.2018

Christine Calder A yawn consists of an extended gaping of the mouth followed by a more rapid closure. In mammals and birds, a long intake of breath and shorter exhale follows the gaping of the mouth, but in other species such as fish, amphibians and snakes there is no intake of breath. But what’s behind a yawn, why does it occur? In the past, people have had many hypotheses. As far back as 400 B.C., Hippocrates thought yawning removed bad air from the lungs before a fever. In the 17th and 18th century, doctors believed yawning increased oxygen in the blood, blood pressure, heart rate and blood flow itself. More recently, consensus moved toward the idea that yawning cools down the brain, so when ambient conditions and temperature of the brain itself increase, yawning episodes increase. Despite all these theories, the truth is that scientists do not know the true biological function of a yawn. What we do know is that yawning occurs in just about every species. It happens when an animal is tired. It can be used as a threat display in some species. Yawning can occur during times of social conflict and stress, something researchers call a displacement behavior. And that wide-open mouth can be contagious, especially in social species such as humans, chimpanzees, bonobos, macaques and wolves. Watching someone yawn – heck, even reading about yawns – can lead you to yawn yourself. Why? © 2010–2018, The Conversation US, Inc.

Keyword: Sleep; Attention
Link ID: 25177 - Posted: 07.06.2018

Laurel Hamers Using opioids gives some brain cells a call to action. Opioid addicts’ brains, examined after death, contain about 50 percent more nerve cells that release a molecule called hypocretin, compared with people who didn’t use the drugs, a new study finds. Giving the opiate morphine to mice also induced similar changes in their brains. But the increase didn’t come from new nerve cells, or neurons, being born. Instead, once-dormant neurons appear to rev up their hypocretin machinery in response to the addictive drugs, researchers report June 27 in Science Translational Medicine. The findings fit with a growing body of research that suggests that hypocretin, a brain chemical that regulates wakefulness and arousal, may also be involved in addiction. “I think there is extensive evidence now that shows that the hypocretin neurons are supporting motivated behavior in general,” and addiction falls under that umbrella, says Rodrigo España, a neurobiologist at Drexel University in Philadelphia who wasn’t involved in the new study. For example, his lab recently showed that rats with a less sensitive hypocretin receptor (and therefore a weaker response to the brain chemical) showed less motivation to seek out cocaine rewards. The new study comes from the opposite angle, showing changes in hypocretin neurons in response to drug use, rather than the other way around. “It does suggest the possibility that part of the reason it’s so hard to get off drugs is there’s this massive change in the brain,” says study coauthor and neuroscientist Jerome Siegel of UCLA. |© Society for Science & the Public 2000 - 2018.

Keyword: Narcolepsy; Drug Abuse
Link ID: 25153 - Posted: 06.28.2018

By Austin Frakt One of the lighter moments along my journey to receiving a sleep apnea diagnosis was learning that “heroic snoring” is a clinical term. It sounds more like an oddball super power — snores that can be clearly heard through walls. Many of us have such a snorer in our lives, and some endure the disruption it causes nightly. We hardly need research to appreciate the difficulties this poses. Yet some studies on it have been done, and they document that snoring can lead to marital disruption, and that snorers’ bed partners can experience insomnia, headaches and daytime fatigue. But heroic (and less-than-heroic) snoring can also be a sign of an even deeper problem: obstructive sleep apnea, which is marked by a collapse of the upper airway leading to shallow breathing or breathing cessation that causes decreases in blood oxygen. Sleep apnea can be downright deadly, and not just for those who have it. It’s associated with a greater risk of depression, heart attacks, strokes and other cardiovascular conditions, as well as insulin resistance. As I learned, there’s no reason to meekly accept sleep apnea: There are many treatment options that can control it. The stakes are not small. In the last five years, crashes involving an Amtrak train in South Carolina, a Long Island Rail Road train, a New Jersey Transit train and a Metro-North train in the Bronx have resulted in multiple deaths, hundreds of injuries and tens of millions of dollars in property damage. Undiagnosed or untreated sleep apnea were blamed in each case. And these are far from the only sleep apnea-related accidents involving trains, buses, tractor-trailers and automobiles. Up to 30 percent of motor vehicle crashes are caused by sleepy drivers. Drivers with sleep apnea are nearly five times more likely to be involved in a motor vehicle accident than other drivers. One study found that 20 percent of American truck drivers admit to falling asleep at traffic lights. © 2018 The New York Times Company

Keyword: Sleep
Link ID: 25138 - Posted: 06.25.2018

By Sean Coughlan BBC News education and family correspondent The colour cyan - between green and blue - is a hidden factor in encouraging or preventing sleep, according to biologists. University of Manchester researchers say higher levels of cyan keep people awake, while reducing cyan is associated with helping sleep. The impact was felt even if colour changes were not visible to the eye. The researchers want to produce devices for computer screens and phones that could increase or decrease cyan levels. Sleep researchers have already established links between colours and sleep - with blue light having been identified as more likely to delay sleep. There have been "night mode" settings for phones and laptops which have reduced blue light in an attempt to lessen the damage to sleep. But the research by biologists at the University of Manchester and in Basel in Switzerland, published in the journal Sleep, has shown the particular impact of the colour cyan. When people were exposed to more or less cyan, researchers were able to measure different levels of the sleep hormone melatonin in people's saliva. Prof Rob Lucas said that it was not necessary for someone to be able to see the difference in colours, as the body reacted to the change even if it was not visible to the naked eye. He said this could also affect other colours which were made using cyan. For instance, there are shades of green that can include cyan - which also can be achieved using other colour combinations. The researchers suggest that versions of the colour using cyan could be used on computer screens if the aim was to keep people awake - such as people working and required to stay alert at night. © 2018 BBC.

Keyword: Biological Rhythms; Sleep
Link ID: 25120 - Posted: 06.22.2018

By Nicholas Bakalar Night owls may be at greater risk for depression than early birds. Previous studies have found a link between a person’s unique circadian rhythm, or chronotype, and depression, but none were able to tell whether sleep habits were a cause or an effect of the disease. This new prospective study, in the Journal of Psychiatric Research, is a step closer to establishing causality. Researchers gathered health and behavioral data on 32,740 women whose average age was 55. Each categorized herself as a definite evening or morning type, a somewhat morning or evening type, or neither. All were free of depression at the start of the study, and over the following four years 2,581 of them developed depression, defined by antidepressant use or a clinical diagnosis. After adjusting for marital status, living alone, being retired, alcohol consumption and other variables, the researchers found that compared to the intermediate types, morning people were 12 percent less likely to develop depression, and night owls 6 percent more likely to develop it. The relationship was linear: the more a woman tended toward the night-owl type, the more likely she was to develop depression. “The effect is modest, a modest association for chronotype and incident depression,” said the lead author, Céline Vetter, an assistant professor at the University of Colorado. “But the overall pattern remains constant. We need to get much deeper into what the genetic and environmental contributions are between mood and chronotype.” © 2018 The New York Times Company

Keyword: Biological Rhythms; Depression
Link ID: 25113 - Posted: 06.21.2018

By Julia Jacobs Humans, it turns out, can annoy more than just one another. In fact, some animal populations are escaping their Homo sapien cohabitants by sleeping more during the day, a new study finds. Mammals across the globe are becoming increasingly nocturnal to avoid humans’ expanding presence, according to the study, published Thursday in Science magazine. The findings show that humans’ presence alone can cause animals across continents — including coyotes, elephants and tigers — to alter their sleep schedules. “We’re just beginning to scratch the surface on how these behavioral changes are affecting entire ecosystems,” said Kaitlyn Gaynor, an ecologist and graduate student in environmental science at the University of California, Berkeley, who led the study. Previous research has found that mammals went from being noctural to being active during both day and night about 65.8 million years ago, roughly 200,000 years after most dinosaurs went extinct. “Species for millions of years have been adapting to diurnal activity, but now we’re driving them back into the night and may be driving natural selection,” Ms. Gaynor said in an interview. The researchers compiled data from 76 studies of 62 species living on six continents in reaching their conclusions. On average, human disruption is making these animals 1.36 times more nocturnal, according to the study. “For example,” it says, “an animal that typically split its activity evenly between the day and night would increase its proportion of nocturnal activity to 68 percent of total activity near human disturbance.” In California’s Santa Cruz mountains, for example, coyotes are opting to sleep more during the day in response to recreational human activities such as hiking and bicycling. As a result, coyotes are eating more nocturnal prey, whose waking hours match up more closely with theirs. Recent research such as this was used to provide data for the new study, Ms. Gaynor said. © 2018 The New York Times Company

Keyword: Biological Rhythms
Link ID: 25093 - Posted: 06.15.2018

Alex Fox Northern fur seals (Callorhinus ursinus) can forgo rapid eye movement sleep for up to two weeks while at sea with no visible hardship, according to new research. This flies in the face of previous studies on land mammals such as rats, in which depriving the animals of rapid eye movement (REM) sleep for a week or more led to problems including weight loss, hypothermia and eventually, death. Nearly all land mammals and birds experience REM sleep. This is the brain's most active sleep phase and has been associated with learning and processing memories. But now, results1 published on 7 June in Current Biology point to another function: regulating brain temperature. Like whales and dolphins, northern fur seals switch off half of their brain to catch some Zs at sea in order to maintain a low level of alertness. The researchers wanted to see whether the seals skipped REM sleep in the water, as whales and dolphins do2. They also thought that the fur seals could offer a good way of investigating the functions of REM sleep without causing the stress of interrupted sleep that can muddy the results of similar studies in other mammals. The study authors used four captive northern fur seals, fitting them with electrodes that recorded electrical activity in the animals’ brains, eyes, muscles and hearts. The scientists allowed or prevented the seals from sleeping on land by raising or lowering the water level in their pool — thereby exposing or submerging a platform they could use to rest. © 2018 Macmillan Publishers Limited,

Keyword: Sleep
Link ID: 25073 - Posted: 06.09.2018

By Carl Zimmer On a December evening in 1951, Eugene Aserinsky, a physiologist at the University of Chicago, placed electrodes on the scalp of his 8-year-old son, Armond, before putting him to bed. Then the scientist retired to another room to watch a row of pens quiver across a rolling sheet of paper, recording the electrical activity in the boy’s facial muscles. Hours later, the pens started to swing wildly. To judge from the chart, it seemed as if Armond were awake, his eyes darting about the room. But when Aserinsky looked in on him, his son was fast asleep. Aserinsky had discovered R.E.M. sleep. Eventually he and other researchers learned that during this state, the brain shifts from low-frequency to high-frequency electrical waves, like those produced in waking hours. When Aserinsky woke his subjects from R.E.M. sleep, they often reported vivid dreams. Almost all mammals experience R.E.M. sleep, but even today researchers debate why it exists. On Thursday, a team of American and Russian researchers reported that fur seals may provide an important clue. While they swim, fur seals switch off R.E.M. sleep entirely. It returns when they come back to land — a pattern never seen before. Jerome M. Siegel, a sleep expert at the University of California, Los Angeles, and a co-author of the new study published Thursday in Current Biology, said that the seals provide evidence that our brains switch to R.E.M. sleep from time to time to generate heat in our skulls. “R.E.M. sleep is like shivering for the brain,” he said. Many scientists have argued that our brains require R.E.M. sleep each night to function properly. One clue comes from experiments in which researchers deprive rats of R.E.M. sleep for a few days. © 2018 The New York Times Company

Keyword: Sleep
Link ID: 25070 - Posted: 06.08.2018

By Ruth Williams The sun’s ultraviolet (UV) radiation is a major cause of skin cancer, but it offers some health benefits too, such as boosting production of essential vitamin D and improving mood. Today (May 17), a report in Cell adds enhanced learning and memory to UV’s unexpected benefits. Researchers have discovered that, in mice, exposure to UV light activates a molecular pathway that increases production of the brain chemical glutamate, heightening the animals’ ability to learn and remember. “The subject is of strong interest, because it provides additional support for the recently proposed theory of ultraviolet light’s regulation of the brain and central neuroendocrine system,” dermatologist Andrzej Slominski of the University of Alabama who was not involved in the research writes in an email to The Scientist. “It’s an interesting and timely paper investigating the skin-brain connection,” notes skin scientist Martin Steinhoff of University College Dublin’s Center for Biomedical Engineering who also did not participate in the research. “The authors make an interesting observation linking moderate UV exposure to . . . [production of] the molecule urocanic acid. They hypothesize that this molecule enters the brain, activates glutaminergic neurons through glutamate release, and that memory and learning are increased.” © 1986-2018 The Scientist

Keyword: Learning & Memory; Biological Rhythms
Link ID: 25052 - Posted: 06.02.2018