Chapter 14. Biological Rhythms, Sleep, and Dreaming

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Links 1 - 20 of 1825

By Jackie Rocheleau Every day about 60,000 people have surgery under general anesthesia in the United States. Often casually compared to falling into a deep sleep, going under is in fact wildly different from your everyday nocturnal slumber. Not only does a person lose the ability to feel pain, form memories, or move—they can’t simply be nudged back into conscious awareness. But occasionally, people do wake unexpectedly—in about 1 out of every 1,000 to 2,000 surgeries, patients emerge from the fog of anesthesia into the harsh light of the operating room while still under the knife. One question that has dogged researchers over the past several decades is whether women are more likely to find themselves in these unfortunate circumstances. A number of recent studies, including a 2023 meta-analysis, suggest that the answer is yes. But the findings are controversial: Other studies have found no differences in waking frequency between the sexes and most of the studies were not designed specifically to identify sex differences. It’s also difficult to know whether other factors might have influenced the results: rates of metabolization of drugs by male and female bodies, as well as variation in kinds of surgeries and anesthetic regimens among study participants. No causal link had been established. Now, a new study published in the Proceedings of the National Academy of Sciences helps untangle some of the mystery. In a series of experiments in mice and in humans, the researchers found that females do wake more easily from anesthesia and that testosterone plays an important role in how quickly and deeply we go under, and how easily we wake up. “There seems to be something hardwired into the female brain that biases it more toward a state of wakefulness,” says University of Pennsylvania anesthesiologist Max Kelz, co-author of the study. © 2024 NautilusNext Inc., All rights reserved.

Keyword: Sexual Behavior; Sleep
Link ID: 29156 - Posted: 02.22.2024

By Carolyn Todd Any sleep tracker will show you that slumber is far from a passive affair. And no stage of sleep demonstrates that better than rapid eye movement, or REM, commonly called dream sleep. “It’s also called paradoxical sleep or active sleep, because REM sleep is actually very close to being awake,” said Dr. Rajkumar Dasgupta, a sleep medicine and pulmonary specialist at the Keck School of Medicine of the University of Southern California. Before scientists discovered REM sleep in the 1950s, it wasn’t clear that much of anything was happening in the brain at night. Researchers today, however, understand sleep as a highly active process composed of very different types of rest — including REM, which in some ways doesn’t seem like rest at all. While the body typically remains “off” during REM sleep, the brain is very much “on.” It’s generating vivid dreams, as well as synthesizing memories and knowledge. Scientists are still working to unravel exactly how this strange state of consciousness works. “It is fair to say that there is a lot left to learn about REM sleep,” Dr. Dasgupta said. But from what researchers do understand, REM is critical to our emotional health and brain function — and potentially even our longevity. Where does REM sleep fall in the sleep cycle? Throughout the night, “We’re going in and out of this rhythmic, symphonic pattern of the various stages of sleep: non-REM 1, 2, 3 and REM,” said Rebecca Robbins, an instructor in medicine at Harvard Medical School and an associate scientist in the division of sleep and circadian disorders at Brigham and Women’s Hospital. © 2024 The New York Times Company

Keyword: Sleep; Neuroimmunology
Link ID: 29128 - Posted: 02.03.2024

Ashley Montgomery In December 1963, a military family named the Gardners had just moved to San Diego, Calif. The oldest son, 17-year-old Randy Gardner, was a self-proclaimed "science nerd." His family had moved every two years, and in every town they lived in, Gardner made sure to enter the science fair. He was determined to make a splash in the 10th Annual Greater San Diego Science Fair. When researching potential topics, Gardner heard about a radio deejay in Honolulu, Hawaii, who avoided sleep for 260 hours. So Gardner and his two friends, Bruce McAllister and Joe Marciano, set out to beat this record. Randy Gardner spoke to NPR's Hidden Brain host Shankar Vedantam in 2017. When asked about his interest in breaking a sleep deprivation record, Gardner said, "I'm a very determined person, and when I get things under my craw, I can't let it go until there's some kind of a solution." Of his scientific trio, Randy lost the coin toss: He would be the test subject who would deprive himself of sleep. His two friends would take turns monitoring his mental and physical reaction times as well as making sure Gardner didn't fall asleep. The experiment began during their school's winter break on Dec. 28, 1963. Three days into sleeplessness, Gardner said, he experienced nausea and had trouble remembering things. Speaking to NPR in 2017, Gardner said: "I was really nauseous. And this went on for just about the entire rest of the experiment. And it just kept going downhill. I mean, it was crazy where you couldn't remember things. It was almost like an early Alzheimer's thing brought on by lack of sleep." But Gardner stayed awake. The experiment gained the attention of local reporters, which, in Gardner's opinion, was good for the experiment "because that kept me awake," he said. "You know, you're dealing with these people and their cameras and their questions." The news made its way to Stanford, Calif., where a young Stanford sleep researcher named William C. Dement was so intrigued that he drove to San Diego to meet Gardner. © 2024 npr

Keyword: Sleep
Link ID: 29120 - Posted: 01.31.2024

By Christian Guay & Emery Brown What does it mean to be conscious? People have been thinking and writing about this question for millennia. Yet many things about the conscious mind remain a mystery, including how to measure and assess it. What is a unit of consciousness? Are there different levels of consciousness? What happens to consciousness during sleep, coma and general anesthesia? As anesthesiologists, we think about these questions often. We make a promise to patients every day that they will be disconnected from the outside world and their inner thoughts during surgery, retain no memories of the experience and feel no pain. In this way, general anesthesia has enabled tremendous medical advances, from microscopic vascular repairs to solid organ transplants. In addition to their tremendous impact on clinical care, anesthetics have emerged as powerful scientific tools to probe questions about consciousness. They allow us to induce profound and reversible changes in conscious states—and study brain responses during these transitions. But one of the challenges that anesthesiologists face is measuring the transition from one state to another. That’s because many of the approaches that exist interrupt or disrupt what we are trying to study. Essentially, assessing the system affects the system. In studies of human consciousness, determining whether someone is conscious can arouse the person being studied—confounding that very assessment. To address this challenge, we adapted a simple approach we call the breathe-squeeze method. It offers us a way to study changes in conscious state without interrupting those shifts. To understand this approach, it helps to consider some insights from studies of consciousness that have used anesthetics. For decades researchers have used electroencephalography (EEG) to observe electrical activity in the brains of people receiving various anesthetics. They can then analyze that activity with EEG readings to characterize patterns that are specific to various anesthetics, so-called anesthetic signatures. © 2024 SCIENTIFIC AMERICAN

Keyword: Consciousness; Sleep
Link ID: 29116 - Posted: 01.27.2024

By Sara Reardon Lustful male marsupials sacrifice their sleep for weeks to make more time for mating1. The antechinus, an Australian marsupial roughly the size of a gerbil, is a rare example of a mammal that mates during a certain season and never again. Roughly every August, male antechinus enter a three-week breeding frenzy in which they mate with every female they can and then die en masse. “It’s very short, very intense,” says zoologist Erika Zaid at La Trobe University in Melbourne, Australia. Males generally live for only one year; females can live for at least a year longer and produce more than one litter. To find out how males make enough time for sex in their short lives, Zaid and her colleagues trapped ten male and five female dusky antechinus (Antechinus swainsonii) and kept them in separate enclosures so they couldn’t mate. They attached activity monitors to the animals’ collars and collected blood samples to measure biomarkers. The researchers found that captive males, but not females, moved around much more and slept less during breeding season than they did the rest of the year. On average, the males’ sleep time per day was around 20% lower during the breeding season than during the non-breeding season ― and one male’s sleep time per day was more than 50% lower. At the end of breeding season, two of the males died within a few hours of one another. The other eight became sterile. To determine whether sleep loss occurs in the wild, Zaid and her colleagues trapped 38 animals from a related species called agile antechinus (A. agilis) before and during breeding season and measured the animals’ oxalic acid, a chemical in the blood whose levels drop when an animal is short on sleep. Males’ oxalic acid levels fell sharply during the breeding season. Unlike the captive females, wild females showed drops as well, suggesting that males were waking them up for shenanigans. Mysterious death © 2024 Springer Nature Limited

Keyword: Sleep; Sexual Behavior
Link ID: 29113 - Posted: 01.27.2024

By Lauren Peace Tampa Bay Times Nina Shand couldn’t stay awake. She had taken afternoon naps since she was a teenager to accommodate her “work hard, play hard” attitude, but when she was in her mid-20s the sleepiness became more severe. Menial computer tasks put her to sleep, and a 20-minute drive across her city, St. Petersburg, Florida, brought on a drowsiness so intense that her eyelids would flutter, forcing her to pull over. She knew something was really wrong when she no longer felt safe behind the wheel. In 2021, she received a diagnosis: narcolepsy, a rare disorder that causes excessive daytime sleepiness. Her doctor prescribed her Adderall, the brand-name version of the amphetamine-powered medication commonly known for treating attention-deficit/hyperactivity disorder. It worked. For the first time in years, Shand, now 28, felt energized. She was no longer struggling at work, sneaking naps, or downing coffees to trick her body into staying awake. She felt hope. But by 2022, a national Adderall shortage meant pharmacies were no longer able to fill her prescription. Shand and countless others across the country were being turned away, left to piece together a new — and often less effective — treatment plan with doctors scrambling to meet their needs. More than a year later, the shortage continues. In October, Democrats in the U.S. House of Representatives implored the FDA and Drug Enforcement Administration to work with drug manufacturers to ensure better supply. “We cannot allow this to be the continuing reality for Americans,” read their letter, led by Rep. Abigail Spanberger (D-Va.). But for now, it is.

Keyword: Sleep; Drug Abuse
Link ID: 29102 - Posted: 01.16.2024

By Laura Sanders In this busy holiday season, many of us multitask. Arctic reindeer are no exception. Reindeer can eat and sleep at the same time, a new study suggests. This timesaving strategy, described December 22 in Current Biology, adds to the number of ingenious ways animals can catch some z’s under tough conditions (SN: 11/30/23). Arctic reindeer are quite busy in the summer — eating when the sun shines around the clock and the food is abundant. Like other ruminants, reindeer spend a considerable amount of time chewing on regurgitated food, making it smaller and easier to digest. Finding time to sleep amid all this cud chewing might be tough. But not if the reindeer could sleep while they chewed. To find out if the reindeer could actually sleep-eat, neuroscientist Melanie Furrer and chronobiologist Sara Meier, along with their colleagues, trained four female Eurasian tundra reindeer (Rangifer tarandus tarandus) to tolerate a pen and electrodes on shaved patches of skin. The process involved some kicks and lots of lichen treats, “which is like candy to them,” says Meier, of the University of Zurich. The researchers were looking for the brain waves that appear during non-REM sleep, a deep, restorative sleep phase. These waves appeared when the reindeer were chewing cud, though the chewing motion itself made it hard to say whether the signal was identical to that of a regular sleep session. “We couldn’t go into detail by looking only at the brain waves, because we have this chewing in there that disturbs it a bit,” says Furrer, also of the University of Zurich. Still, other signs also pointed to sleep while chewing. The reindeer were calm while chewing, often with their eyes closed. “They were in a very relaxed state that resembles the body position of non-REM sleep,” Furrer says. Ruminating reindeer were also harder to disturb; rustling from neighboring reindeer was less likely to get a look from a ruminating reindeer. When reindeer are kept awake, they need catch-up recovery sleep. But time spent chewing decreased this time spent in recovery sleep, the researchers found. © Society for Science & the Public 2000–2023.

Keyword: Sleep; Attention
Link ID: 29072 - Posted: 12.31.2023

By Elise Cutts On a summer night in the Bay of Naples, hordes of worms swam upward from the seagrass toward the water’s surface under the light of a waning moon. Not long before, the creatures began a gruesome sexual metamorphosis: Their digestive systems withered, and their swimming muscles grew, while their bodies filled with eggs or sperm. The finger-length creatures, now little more than muscular bags of sex cells, fluttered to the surface in unison and, over a few hours, circled each other in a frantic nuptial dance. They released countless eggs and sperm into the bay — and then the moonlit waltz ended in the worms’ deaths. The marine bristle worm Platynereis dumerilii gets only one chance to mate, so its final dance had better not be a solo. To ensure that many worms congregate at the same time, the species synchronizes its reproductive timing with the cycles of the moon. How can an undersea worm tell when the moon is at its brightest? Evolution’s answer is a precise celestial clock wound by a molecule that can sense moonbeams and sync the worms’ reproductive lives to lunar phases. No one had ever seen how one of these moonlight molecules worked. Recently, however, in a study published in Nature Communications, researchers in Germany determined the different structures that one such protein in bristle worms takes in darkness and in sunlight. They also uncovered biochemical details that help explain how the protein distinguishes between brighter sunbeams and softer moonglow. It’s the first time that scientists have determined the molecular structure of any protein responsible for syncing a biological clock to the phases of the moon. “I’m not aware of another system that has been looked at with this degree of sophistication,” said the biochemist Brian Crane of Cornell University, who was not involved in the new study. © 2023 An editorially independent publication supported by the Simons Foundation.

Keyword: Biological Rhythms; Evolution
Link ID: 29062 - Posted: 12.22.2023

By Carl Zimmer Neanderthals were morning people, a new study suggests. And some humans today who like getting up early might credit genes they inherited from their Neanderthal ancestors. The new study compared DNA in living humans with genetic material retrieved from Neanderthal fossils. It turns out that Neanderthals carried some of the same clock-related genetic variants as do people who report being early risers. Since the 1990s, studies of Neanderthal DNA have exposed our species’ intertwined history. About 700,000 years ago, our lineages split apart, most likely in Africa. While the ancestors of modern humans largely stayed in Africa, the Neanderthal lineage migrated into Eurasia. About 400,000 years ago, the population split in two. The hominins who spread west became Neanderthals. Their cousins to the east evolved into a group known as Denisovans. The two groups lived for hundreds of thousands of years, hunting game and gathering plants, before disappearing from the fossil record about 40,000 years ago. By then, modern humans had expanded out of Africa, sometimes interbreeding with Neanderthals and Denisovans. And today, fragments of their DNA can be found in most living humans. Research carried out over the past few years by John Capra, a geneticist at the University of California, San Francisco, and other scientists suggested that some of those genes passed on a survival advantage. Immune genes inherited from Neanderthals and Denisovans, for example, might have protected them from new pathogens they had not encountered in Africa. Dr. Capra and his colleagues were intrigued to find that some of the genes from Neanderthals and Denisovans that became more common over generations were related to sleep. For their new study, published in the journal Genome Biology and Evolution, they investigated how these genes might have influenced the daily rhythms of the extinct hominins. © 2023 The New York Times Company

Keyword: Biological Rhythms; Evolution
Link ID: 29052 - Posted: 12.16.2023

Maria Godoy What do you do when you can't get your kids to settle down to go to sleep? For a growing number of parents, the answer is melatonin. Recent research shows nearly one in five school-age children and adolescents are now using the supplement on a regular basis. Pediatricians say that's cause for alarm. "It is terrifying to me that this amount of an unregulated product is being utilized," says Dr. Cora Collette Breuner, a professor of pediatrics at the University of Washington. Melatonin is a hormone produced by your brain that helps regulate sleep-wake cycles. It's also sold as a dietary supplement and is widely used as a sleep aid. Sponsor Message Lauren Hartstein, a postdoctoral researcher who studies sleep in early childhood at the University of Colorado, Boulder, says she first got an inkling of melatonin's growing use in children and adolescents while screening families to participate in research. "All of a sudden last year, we noticed that there was a big uptick in the number of parents who were regularly giving [their kids] melatonin," Hartstein says. Hartstein and her colleagues wanted to learn more about just how widely melatonin is being used in kids. So they surveyed the parents of nearly 1,000 children between the ages of 1 to 14 across the country. She was surprised by just how many kids are taking the supplement. "Nearly 6% of preschoolers, [ages] 1 to 4, had taken it, and that number jumped significantly higher to 18% and 19% for school-age children and pre-teens," she says. As Hartstein and her co-authors recently reported in the journal JAMA Pediatrics, most of the kids that were using melatonin had been on it for a year or longer. And 1 in 4 kids were taking it every single night. © 2023 npr

Keyword: Biological Rhythms; Sleep
Link ID: 29047 - Posted: 12.16.2023

By Roberta McLain Dreams have fascinated people for millennia, yet we struggle to understand their purpose. Some theories suggest dreams help us deal with emotions, solve problems or manage hidden desires. Others postulate that they clean up brain waste, make memories stronger or deduce the meaning of random brain activity. A more recent theory suggests nighttime dreams protect visual areas of the brain from being co-opted during sleep by other sensory functions, such as hearing or touch. David Eagleman, a neuroscientist at Stanford University, has proposed the idea that dreaming is necessary to safeguard the visual cortex—the part of the brain responsible for processing vision. Eagleman’s theory takes into account that the human brain is highly adaptive, with certain areas able to take on new tasks, an ability called neuroplasticity. He argues that neurons compete for survival. The brain, Eagleman explains, distributes its resources by “implementing a do-or-die competition” for brain territory in which sensory areas “gain or lose neural territory when inputs slow, stop or shift.” Experiences over a lifetime reshape the map of the brain. “Just like neighboring nations, neurons stake out their territory and chronically defend them,” he says. Eagleman points to children who have had half their brain removed because of severe health problems and then regain normal function. The remaining brain reorganizes itself and takes over the roles of the missing sections. Similarly, people who lose sight or hearing show heightened sensitivity in the remaining senses because the region of the brain normally used by the lost sense is taken over by other senses. Reorganization can happen fast. Studies published in 2007 and 2008 by Lotfi Merabet of Harvard Medical School and his colleagues showed just how quickly this takeover can happen. The 2008 study, in which subjects were blindfolded, revealed that the seizing of an idle area by other senses begins in as little as 90 minutes. And other studies found that this can occur within 45 minutes. When we sleep, we can smell, hear and feel, but visual information is absent—except during REM sleep. © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep; Vision
Link ID: 29045 - Posted: 12.13.2023

Perspective by Michael Varnum and Ian Hohm A growing body of research in psychology and related fields suggests that winter brings some profound changes in how people think, feel and behave. The natural and cultural changes that come with winter often occur simultaneously, making it challenging to tease apart the causes underlying these seasonal swings. Live well every day with tips and guidance on food, fitness and mental health, delivered to your inbox every Thursday. We recently conducted an extensive survey of these findings with research colleagues Alexandra Wormley, a social psychologist at Arizona State University, and Mark Schaller, a psychologist at the University of British Columbia. Wintertime blues and a long winter’s nap Do you find yourself feeling down in the winter months? You’re not alone. As the days grow shorter, the American Psychiatric Association estimates that about 5 percent of Americans will experience a form of depression known as seasonal affective disorder, or SAD. People experiencing SAD tend to have feelings of hopelessness, decreased motivation to take part in activities they generally enjoy, and lethargy. Even those who don’t meet the clinical threshold for this disorder may see increases in anxiety and depressive symptoms. Scientists link SAD and more general increases in depression in the winter to decreased exposure to sunlight, which leads to lower levels of the neurotransmitter serotonin. Consistent with the idea that sunlight plays a key role, SAD tends to be more common in more northern regions of the world, such as Scandinavia and Alaska, where the days are shortest and the winters longest. Humans, special as we may be, are not unique in showing some of these seasonally linked changes. For instance, our primate relative the Rhesus macaque shows seasonal declines in mood.

Keyword: Biological Rhythms; Depression
Link ID: 29043 - Posted: 12.13.2023

By Siddhant Pusdekar In the deepest stage of sleep, slow waves of electrical activity travel through your brain. They help consolidate memories and flush out the buildup of unwanted chemicals, getting you ready for the day. This midnight orchestra is responsible for many of the benefits of a good night’s sleep, such as improved attention, mood and energy levels. Scientists at the University of California, Berkeley, recently found that for some people, these waves could also serve as early warning signs of diabetes. The results, published in July in Cell Reports Medicine, suggest that getting a restful sleep may help control high blood sugar. People with type 2 diabetes are unable to metabolize sugar, leading to a damaging excess concentration in the blood. The approximately 515 million people globally with type 2 diabetes can manage blood sugar through diet, exercise and medications such as insulin. But researchers and clinicians have observed that quality of sleep seems to influence blood sugar, too. “We have known that something magic happens during sleep,” says New York University neuroscientist Gyorgy Buzsaki about the links between sleep and metabolism. Yet the mechanism behind that relationship has been a mystery, he says. To investigate, the July study’s co-lead author Raphael Vallat, then a postdoctoral researcher at U.C. Berkeley, analyzed blood glucose and sleep measurements from two large independent public datasets. In the first analysis, Vallat and his colleagues examined sleep patterns measured from polysomnography, a standard assessment that doctors recommend for people with sleep problems. The procedure, typically conducted at night, involves placing a bunch of wires on different parts of the head to record activity in specific brain regions. The ends of the wires act like “microphones” that “hear” brain waves, explains Vyoma Shah, a graduate student at U.C. Berkeley and co-lead author of the paper. Squiggles of different shapes and sizes on the polysomnography graphs represent the ebbs and flows of electrical activity in people’s head as they sleep throughout the night. It is only a surface-level view, however. © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep; Obesity
Link ID: 29035 - Posted: 12.09.2023

By Jake Buehler Nesting chinstrap penguins take nodding off to the extreme. The birds briefly dip into a slumber many thousands of times per day, sleeping for only seconds at a time. The penguins’ breeding colonies are noisy and stressful places, and threats from predatory birds and aggressive neighbor penguins are unrelenting. The extremely disjointed sleep schedule may help the penguins to protect their young while still getting enough shut-eye, researchers report in the Dec. 1 Science. The findings add to evidence “that avian sleep can be very different from the sleep of land mammals,” says UCLA neuroscientist Jerome Siegel. Nearly a decade ago, behavioral ecologist Won Young Lee of the Korea Polar Research Institute in Incheon noticed something peculiar about how chinstrap penguins (Pygoscelis antarcticus) nesting on Antarctica’s King George Island were sleeping. They would seemingly doze off for very short periods of time in their cacophonous colonies. Then in 2018, Lee learned about frigate birds’ ability to steal sleep while airborne on days-long flights. Lee teamed up with sleep ecophysiologist Paul-Antoine Libourel of the Lyon Neuroscience Research Center in France and other researchers to investigate the penguins’ sleep. In 2019, the team studied the daily sleep patterns of 14 nesting chinstrap penguins using data loggers mounted on the birds’ backs. The devices had electrodes surgically implanted into the penguins’ brains for measuring brain activity. Other instruments on the data loggers recorded the animals’ movements and location. Nesting penguins had incredibly fragmented sleep patterns, taking over 600 “microsleeps” an hour, each averaging only four seconds, the researchers found. At times, the penguins slept with only half of their brain; the other half stayed awake. All together, the oodles of snoozes added up, providing over 11 hours of sleep for each brain hemisphere across more than 10,000 brief sleeps each day. © Society for Science & the Public 2000–2023.

Keyword: Sleep; Evolution
Link ID: 29028 - Posted: 12.02.2023

By Erin Garcia de Jesús A new brain-monitoring device aims to be the Goldilocks of anesthesia delivery, dispensing drugs in just the right dose. No physician wants a patient to wake up during surgery — nor do patients. So anesthesiologists often give more drug than necessary to keep patients sedated during medical procedures or while on lifesaving machines like ventilators. But anesthetics can sometimes be harmful when given in excess, says David Mintz, an anesthesiologist at Johns Hopkins University. For instance, elderly people with cognitive conditions like dementia or age-related cognitive decline may be at higher risk of post-surgical confusion. Studies also hint that long periods of use in young children might cause behavioral problems. “The less we give of them, the better,” Mintz says. An automated anesthesia delivery system could help doctors find the right drug dose. The new device monitored rhesus macaques’ brain activity and supplied a common anesthetic called propofol in doses that were automatically adjusted every 20 seconds. Fluctuating doses ensured the animals received just enough drug — not too much or too little — to stay sedated for 125 minutes, researchers reported October 31 in PNAS Nexus. The study is a step toward devising and testing a system that would work for people. © Society for Science & the Public 2000–2023.

Keyword: Consciousness; Pain & Touch
Link ID: 29021 - Posted: 11.26.2023

By Timmy Broderick Smell is probably our most underappreciated sense. “If you ask people which sense they would be most willing to give up, it would be the olfactory system,” says Michael Leon, a neurobiologist at the University of California, Irvine. But a loss of smell has been linked to health complications such as depression and cognitive decline. And mounting evidence shows that olfactory training, which involves deliberately smelling strong scents on a regular basis, may help stave off that decline. Now a team of researchers led by Leon has successfully boosted cognitive performance by exposing people to smells while they sleep. Twenty participants—all older than 60 years and generally healthy—received six months of overnight olfactory enrichment, and all significantly improved their ability to recall lists of words compared with a control group. The study appeared in Frontiers in Neuroscience. The scientists are unsure about how the overnight odors may have produced this result, but Leon notes that the neurons involved in olfaction have “direct superhighway access” to brain regions related to memory and emotion. In participants who received the treatment, the study authors observed physical changes in a brain structure that connects the memory and emotional centers—a pathway that often deteriorates as people age, especially in those with Alzheimer's disease. Previous successful attempts to boost memory with odors typically relied on complicated interventions with multiple exposures a day. If the nighttime treatment proves successful in larger trials, it promises to be a less intrusive way to achieve similar effects, says Vidya Kamath, a neuropsychologist at the Johns Hopkins University School of Medicine, who was not involved in the recent study. Larger trials may also help answer some remaining questions. The new study used widely available essential oils such as rose and eucalyptus, but researchers aren't sure if just any odor would get the same results. They don't know how much an odor's qualities—whether it's foul or pleasant to people, for example—affects the cognitive gains. It is also unclear how much novelty plays a role, says Michał Pieniak, a psychology researcher at the University of Wroclaw in Poland who has studied olfactory training. © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep; Learning & Memory
Link ID: 29010 - Posted: 11.18.2023

Sean O'Donnell Human-driven climate change is increasingly shaping the Earth’s living environments. Rising temperatures, rapid shifts in rainfall and seasonality, and ocean acidification are presenting altered environments to many animal species. How do animals adjust to these new, often extreme, conditions? Animal nervous systems play a central role in both enabling and limiting how they respond to changing climates. Two of my main research interests as a biologist and neuroscientist involve understanding how animals accommodate temperature extremes and identifying the forces that shape the structure and function of animal nervous systems, especially brains. The intersection of these interests led me to explore the effects of climate on nervous systems and how animals will likely respond to rapidly shifting environments. All major functions of the nervous system – sense detection, mental processing and behavior direction – are critical. They allow animals to navigate their environments in ways that enable their survival and reproduction. Climate change will likely affect these functions, often for the worse. Changing temperatures shift the energy balance of ecosystems – from plants that produce energy from sunlight to the animals that consume plants and other animals – subsequently altering the sensory worlds that animals experience. It is likely that climate change will challenge all of their senses, from sight and taste to smell and touch. Animals like mammals perceive temperature in part with special receptor proteins in their nervous systems that respond to heat and cold, discriminating between moderate and extreme temperatures. These receptor proteins help animals seek appropriate habitats and may play a critical role in how animals respond to changing temperatures.

Keyword: Biological Rhythms
Link ID: 29007 - Posted: 11.15.2023

By Jocelyn Solis-Moreira When the alarm goes off in the early morning, it’s tempting to hit the snooze button and curl back under the warm covers for a few more minutes of slumber. This repeated postponing of the buzzer is often thought of as a bad habit—one that creates not only a lazy start to a day but also a fragmented sleep pattern that’s detrimental to health. Now, however, a growing body of recent research is contradicting this notion. A new study published in the Journal of Sleep Research found that people who regularly press the snooze button lost only about six minutes of sleep per night—and that it didn’t affect their morning sleepiness or mood. In fact, tests showed that it actually improved cognition. This adds to research in 2022 that also found chronic snoozers generally felt no sleepier than nonsnoozers. “Snoozing for a limited time in the morning is probably not bad for you,” says the new study’s lead author Tina Sundelin, a sleep researcher at Stockholm University. She says that her study is one of few that have directly tested snoozing’s effect on sleep health, and it supplies evidence that snoozing doesn’t break up sleep in a harmful way. Scientific American spoke with sleep experts on the science of snoozing and how the habit may actually be good for you—if you do it right. The Potential Benefits of Snoozing Snoozing does shorten sleep, Sundelin says, but she maintains that it’s not as bad as scientists once thought. Past research has suggested that the extra minutes snoozers get don’t really help them feel more rested—and repeatedly waking up and trying to sleep again has been thought to prevent the restorative stages of sleep, including rapid-eye movement (REM). Other research has suggested that waking someone in the middle of their sleep cycle causes them to feel sleepier throughout the day. “If you disturb someone’s sleep, it’s not good-quality sleep, and they often feel tired afterwards—but this [idea] is based on a whole night of sleep fragmentation,” explains Sundelin, who adds that most theories about snoozing are “inferred from what we know about sleep in general.” © 2023 SCIENTIFIC AMERICAN,

Keyword: Sleep
Link ID: 29005 - Posted: 11.15.2023

Catherine Sweeney - WPLN NASHVILLE, Tenn. — High school classes start so early around this city that some kids get on buses at 5:30 in the morning. Just 10% of public schools nationwide start before 7:30 a.m., according to federal statistics. But in Nashville, classes start at 7:05 — a fact the new mayor, Freddie O'Connell, has been criticizing for years. "It's not a badge of honor," he said when he was still a city council member. Since his election in September, O'Connell has announced that pushing back school start times is a cornerstone of the education policy he is promoting. He and others around the country have been trying to stress that teenagers aren't lazy or to blame for getting too little sleep. It's science. Sponsor Message "All teenagers have this shift in their brain that causes them to not feel sleepy until about 10:45 or 11 at night," said Kyla Wahlstrom, a senior research fellow at the University of Minnesota in the College of Education and Human Development. She studies how education policy affects learning, and she used to be a teacher. "It's a shift that is biologically determined." Sleep deprivation in teenagers is linked to mental health struggles, worse grades, traffic accidents, and more. That's why states including California and Florida have mandated later start times. Individual districts across the country — including some in Tennessee — have made the same change. But resistance to later starts is less about the science than it is about logistical and financial difficulties, especially with basics like busing. Melatonin makes people feel drowsy. The brain starts producing it when it gets dark outside, and its production peaks in the middle of the night. Adolescents' brains start releasing melatonin about three hours later than adults' and younger children's brains, according to the American Chemical Society. When teens wake up early, their brains are still producing melatonin. © 2023 npr

Keyword: Biological Rhythms; Sleep
Link ID: 28995 - Posted: 11.11.2023

By Regina G. Barber What your parents didn't tell you about pulling an all-nighter? It might just ease depression for several days. At least, that's what researchers found happened to mice in a study published in the journal Neuron Thursday. Most people who've stayed up all night know the "tired and wired" feeling they get the next day. The body might be exhausted, but the brain feels jittery, hyperactive or even giddy. Even after these changes wear off, sleep loss can have a strong antidepressant effect in people that lasts several days. But researchers hadn't figured out why sleeplessness might have this effect —until this study from neurobiologists at Northwestern University. To study all of this, the team looked at the effects of sleep loss in mice. They induced sleep loss in some of the mice, while the others got a typical night's rest. They found that after this sleepless night, the mice were more excitable, more aggressive, more sexual and less depressed than mice that got a regular amount of sleep. Of course, researchers can't just ask mice whether they feel "less depressed." Instead, they created a depression-like state in all the mice before either disrupting their sleep or allowing them to rest by repeatedly giving them small shocks. In response to these shocks, the mice entered a depressive-like state and eventually stopped trying to escape their cages. Then, they tested the mice's response to shocks again. The ones that had stayed up all night showed a reversed depressive state, indicated by more attempts to escape the shocks. Dopamine is responsible for the brain's reward response. Changes in the brain's dopamine system have also been implicated in conditions like depression and in sleep regulation. And so, to see how the mice's brains responded to their sleepless night, the researchers measured dopamine neuron activity. They saw that sleep-deprived mice showed higher dopamine activity in three regions: the prefrontal cortex, nucleus accumbens and hypothalamus. © 2023 npr

Keyword: Sleep; Depression
Link ID: 28985 - Posted: 11.04.2023