Chapter 14. Biological Rhythms, Sleep, and Dreaming

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By Kevin McCarthy There’s a dearth of safety data for melatonin, but there are a number of potential concerns, especially for children. “I think we just don’t know what the potential long-term effects are, particularly when you’re talking about young children,” said Dr. Judith Owens, director of the Center for Pediatric Sleep Disorders at Boston Children’s Hospital. “Parents really need to understand that there are potential risks.” The pineal gland in the brain ramps up production of the hormone melatonin in the evening, as light fades, to encourage sleep, and it turns down production in the early morning hours. Synthetic forms of the hormone are also sold as a dietary supplement; because melatonin is found in some foods, like barley, olives and walnuts, it is regulated as a nutritional supplement rather than a drug, as most other hormones are. In adults, studies have found melatonin to be effective for jet lag and some sleep disorders. It is also hugely popular as a sleep aid for children and can be useful for sleep disorders among those with attention-deficit disorders or autism, Dr. Owens said. “I rarely see a family come in with a child with insomnia who hasn’t tried melatonin,” she said. “I would say at least 75 percent of the time when they come in to see us” at the sleep clinic, “they’re either on melatonin or they’ve tried it in the past.” While short-term use of the hormone is generally considered safe, it can have side effects, including headaches, dizziness and daytime grogginess, which could pose a risk for drivers. Melatonin can also interfere with blood pressure, diabetes and blood thinning medications. © 2017 The New York Times Company

Keyword: Sleep; Hormones & Behavior
Link ID: 23060 - Posted: 01.06.2017

Erin Ross What lengths would you go to stifle the thunderous snorts and buzz-saw growls of a spouse or roommate, just so you can get a good night's sleep? Dozens of anti-snoring devices crowd the market, ranging from slightly absurd to moderately torturous. "Some of them are more medieval than others," says Dr. Kim Hutchison, associate professor of sleep medicine in the department of neurology at Oregon Health and Science University in Portland, Ore. And some of the devices, she says, even have some basis in fact. "When you sleep, the back of your throat relaxes. That narrows your airway and, as you're breathing in, it causes it to vibrate," explains Hutchison. So, many anti-snoring products are aimed at opening up that airway, or the tunnels that lead to it. For example, you can buy hollow nose plugs that, instead of closing the nostrils, prop them open. "If you have a deviated septum or something like that, those could help open up your nose and decrease snoring," says Hutchison, but they won't help everyone because "most snoring appears in the back of your throat." Other devices are designed to force sleepers to turn on their sides. "Sleeping on your back makes your tongue block your airway a little, sort of like the skinny part of a balloon, when you let air out of it," Hutchison says. So some devices combine straps and pillows that make sleeping on your back uncomfortable — or poke you if you roll over. © 2017 npr

Keyword: Sleep
Link ID: 23053 - Posted: 01.04.2017

Jon Hamilton For patients with serious brain injuries, there's a strong link between sleep patterns and recovery. A study of 30 patients hospitalized for moderate to severe traumatic brain injuries found that sleep quality and brain function improved in tandem, researchers reported Wednesday in the journal Neurology. Patients who still had low levels of consciousness and cognitive functioning would "sleep for a couple of minutes and then wake up for a couple of minutes," both day and night, says Nadia Gosselin, the study's senior author and an assistant professor in the psychology department at the University of Montreal. But "when the brain recovered, the [normal] sleep-wake cycle reappeared," Gosselin says. The results raise the possibility that patients with brain injuries might recover more quickly if hospitals took steps to restore normal sleep patterns, Gosselin says. Drugs are one option, she says. Another is making sure patients are exposed to sunlight or its equivalent during the day and at night rest in a dark, quiet environment. "I think bad sleep can have bad consequences for brain recovery," she says. The findings are consistent with other research showing that "sleep is essential to restore body and brain functions," according to an editorial accompanying the study. The editorial was written by Andrea Soddu of the University of Western Ontario, and Claudio Bassetti of University Hospital Inselspital Bern in Switzerland. © 2016 npr

Keyword: Sleep; Brain Injury/Concussion
Link ID: 23012 - Posted: 12.23.2016

By Alison Howell What could once only be imagined in science fiction is now increasingly coming to fruition: Drones can be flown by human brains' thoughts. Pharmaceuticals can help soldiers forget traumatic experiences or produce feelings of trust to encourage confession in interrogation. DARPA-funded research is working on everything from implanting brain chips to "neural dust" in an effort to alleviate the effects of traumatic experience in war. Invisible microwave beams produced by military contractors and tested on U.S. prisoners can produce the sensation of burning at a distance. What all these techniques and technologies have in common is that they're recent neuroscientific breakthroughs propelled by military research within a broader context of rapid neuroscientific development, driven by massive government-funded projects in both America and the European Union. Even while much about the brain remains mysterious, this research has contributed to the rapid and startling development of neuroscientific technology. And while we might marvel at these developments, it is also undeniably true that this state of affairs raises significant ethical questions. What is the proper role – if any – of neuroscience in national defense or war efforts? My research addresses these questions in the broader context of looking at how international relations, and specifically warfare, are shaped by scientific and medical expertise and technology. 2016 © U.S. News & World Report L.P.

Keyword: Attention; Sleep
Link ID: 22944 - Posted: 12.03.2016

By BENEDICT CAREY The same digital screens that have helped nurture a generation of insomniacs can also help restore regular sleep, researchers reported on Wednesday. In a new study, more than half of chronic insomniacs who used an automated online therapy program reported improvement within weeks and were sleeping normally a year later. The new report, published in the journal JAMA Psychiatry, is the most comprehensive to date suggesting that many garden-variety insomniacs could benefit from the gold standard treatment — cognitive behavior therapy — without ever having to talk to a therapist. At least one in 10 adults has diagnosable insomnia, which is defined as broken, irregular, inadequate slumber at least three nights a week for three months running or longer. “I’ve been an insomniac all my life, I’ve tried about everything,” said Dale Love-Callon, 70, a math tutor living in Rancho Palos Verdes, Calif., who recently used the software. “I don’t have it 100 percent conquered, but I’m sleeping much better now.” Previous studies have found that online sleep therapy can be effective, but most have been smaller, or focused on a particular sleep-related problem, like depression. The new trial tested the digital therapy in a broad, diverse group of longtime insomniacs whose main complaint was lack of sleep. Most had used medication or supplements over the years, and some still did. “These results suggest that there are a group of patients who can benefit without the need of a high-intensity intervention,” like face-to-face therapy, said Jack Edinger, a professor in the department of medicine at National Jewish Health in Denver, who was not a part of the study. “We don’t know yet exactly who they are — the people who volunteer for a study like this in first place are self-motivated — but they’re out there.” © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22939 - Posted: 12.01.2016

By Andy Coghlan Don’t go to bed angry. Now there’s evidence for this proverb: it’s harder to suppress bad memories if you sleep on them. The discovery could reveal new ways to treat people who suffer from conditions like post-traumatic stress disorder, and reinforces an earlier idea that it is possible to suppress bad memories through sleep deprivation. “The results are of major interest for treating the frequent clinical problem of unwanted memories, memories of traumatic events being the most prominent example,” says Christoph Nissen at the University of Freiburg Medical Center in Germany, who was not involved in the work. In the study, 73 male students memorised 26 mugshots, each paired with a disturbing image, such as a mutilated body, corpse or crying child. The next day they were asked to recall the images associated with half the mugshots and actively try to exclude memories of the rest of the associated images. The group were then directed to memorise another 26 pairs of mugshots and nasty images. Half an hour later they again thought about half the associated images and actively suppressed memories of the rest. Finally, they were asked to describe the image associated with each of the 52 mugshots. The idea was to see if trying to suppress a bad memory works better before or after sleep. © Copyright Reed Business Information Ltd.

Keyword: Sleep; Learning & Memory
Link ID: 22933 - Posted: 11.30.2016

By Louisa J. Steinberg “You've got to be kidding me, Doc. I can barely keep my eyes open as it is, and you want me to pull an all-nighter?” I smiled. “Yes, exactly that. Maybe even two or three.” It started out benignly enough. Jodi (not the patient's real name) had been feeling more stressed between meeting the growing demands of her high-stakes job in business management and shouldering more chores while her husband was away on business trips. Strapped for time, she started neglecting her usual self-care routines—eating healthy, exercising, taking time to relax. Not surprisingly, her mood was poor. Things soon grew worse. She no longer enjoyed activities that were usually the highlight of her day: story time with her children, chatting on the phone with her mom, reading a book. Although she was constantly exhausted, she could not get a good night's sleep; she would toss and turn and still feel tired even when she slept in. Her performance at work had also been suffering; she began missing days because she just couldn't get out of bed. Jodi knows she should have recognized these warning signs sooner. She had experienced major depression twice before, once in college and again in her late 20s after a breakup. Now in her late 30s, she had been off antidepressants for years. Yet she found herself back in that dark place, barely eating and unable to concentrate enough to read even a short paragraph. Her thoughts circled around the same unpleasant memories and nagging fears. She felt hopeless and guilty. © 2016 Scientific American

Keyword: Depression; Sleep
Link ID: 22924 - Posted: 11.29.2016

By C. CLAIBORNE RAY Q. Is a night’s sleep physiologically beneficial even if it includes emotionally disturbing nightmares? A. Almost certainly yes, said Dr. Neomi Shah, a specialist at the Mount Sinai Integrative Sleep Center in New York. Despite the problems nightmares can cause, sleeping and having them is better than not sleeping, research suggests. Nightmares can make it difficult to sleep and interfere with daytime functioning, but physiological indicators of sleep patterns and quality do not differ in people who have nightmares, Dr. Shah said. Frequent long, distressing and vivid dreams often wake people and cause problems like insomnia and poor sleep quality, she said. Research has also consistently demonstrated that nightmares can harm general well-being, affect mood and elevate stress. Some studies suggest there are measurable sleep problems for people who have nightmares, while others show no difference. The studies that show such a link found that people who woke up stayed awake longer and that certain stages of sleep did not last as long. But people in those studies who had nightmares also had longer periods of rapid eye movement, or REM, sleep, when most dreaming occurs. A weakness of these studies is that they were not conducted in the subjects’ normal sleeping environment. A more recent study in such an environment found no differences in so-called sleep architecture, sleep-cycle and REM durations, or sleep patterns for just the nights with nightmares. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22921 - Posted: 11.29.2016

Laura Beil NEW ORLEANS — Chronic sleep problems are associated with atrial fibrillation — a temporary but dangerous disruption of heart rhythm — even among people who don’t suffer from sleep apnea. An analysis of almost 14 million patient records has found that people suffering from insomnia, frequent waking and other sleep issues are more likely than sound sleepers to experience a condition in which the upper chambers of the heart quiver instead of rhythmically beating, allowing blood to briefly stagnate. “Even if you don’t have sleep apnea, is there something about sleep disruption that puts you at a higher risk of fibrillation,” said Gregory Marcus, a cardiologist at the University of California, San Francisco. “We should put a higher priority on studying sleep itself.” Marcus and Matthew Christensen, from the University of Michigan, presented their results November 14 at the annual meeting of the American Heart Association. People with atrial fibrillation have double the risk of having a heart attack, and up to five times the risk of stroke. Although the heart condition can be a consequence of aging, its prevalence is rising at about 4 percent per year for reasons that aren’t totally explained. In the United States, about 5 million people currently have the condition, and that number is expected to rise to 12 million by 2030. A large body of studies has found that sleep apnea, which occurs when a person stops breathing during the night, can lead to atrial fibrillation and a host of other health concerns. Identifying a risk of atrial fibrillation among people with no sleep apnea is unexpected, says Richard Becker, director of the University of Cincinnati Heart, Lung & Vascular Institute, who was not part of the study. |© Society for Science & the Public 2000 - 2016.

Keyword: Sleep
Link ID: 22872 - Posted: 11.16.2016

By Jessica Hamzelou You’ve got a spare hour before a big exam. How should you spend it? It seems napping is just as effective as revising, and could even have a longer-lasting impact. Repeatedly revising information to learn it makes sense. “Any kind of reactivation of a memory trace will lead to it being strengthened and reconsolidated,” says James Cousins at the Duke-NUS Medical School in Singapore. “With any memory, the more you recall it, the stronger the memory trace.” However, sleep is also thought to be vital for memory. A good night’s sleep seems to help our brains consolidate what we’ve learned in the day, and learning anything when you’re not well rested is tricky. Many people swear by a quick afternoon kip. So if you’ve got an hour free, is it better to nap or revise? Cousins, along with Michael Chee and their colleagues, also at Duke-NUS Medical School, set out to compare the two options. The team mocked-up a real student experience, and had 72 volunteers sit through presentations of about 12 different species of ants and crabs. The participants were asked to learn all about these animals, including their diets and habitats, for example. After 80 minutes of this, the students were given an hour to either watch a film, have a nap, or revise what they had just learned. After this hour, they had another 80 minutes of learning. Then they had to sit an exam in which they were asked 360 questions about the ants and the crabs. “The napping group got the best scores,” says Cousins, whose work was presented at the Society for Neuroscience annual meeting in San Diego, California on Tuesday. © Copyright Reed Business Information Ltd.

Keyword: Sleep; Learning & Memory
Link ID: 22871 - Posted: 11.16.2016

By Anna Azvolinsky In January 1983, 22-year-old Amita Sehgal arrived in New York City from India to visit her oldest sister, who was due to have a baby. Sehgal had just been rejected from the molecular biology PhD programs at Rockefeller University and Columbia University. “I felt that I had no prospects,” says the University of Pennsylvania professor of neuroscience. She had heard about a Cornell University in NYC, so she and her other sister walked the streets of Manhattan asking its whereabouts. “Someone told us Cornell was hundreds of miles away in Ithaca, and that I must have been asking about the medical school. I had no idea, but I said ‘Yes’ and was directed to the Upper East Side.” Sehgal walked into the medical school, inquired about their PhD program, and was told that the application deadline for the program was that very day. “I sat in the office and filled out the application, wrote my essay, and handed it in!” she says. A few months later, Sehgal was admitted into the genetics program. Sehgal’s parents had also joined the visit and were returning to India in July, shortly before she started the PhD program. “It was fortuitous the way things worked out. My parents were comfortable leaving me in New York because my oldest sister was living there.” One month later, however, her sister and family moved to Florida, and Sehgal was alone, living in Cornell housing. “The first six months were really, really rough,” she says. Cornell had dissolved the genetics program to which Sehgal had been admitted and offered her tuition support with no stipend—and that only for the first semester. “My parents and sister were in no position to help me financially,” she says. Sehgal found a professor at the adjacent Memorial Sloan Kettering Cancer Center (MSKCC), Raju Chaganti, who gave her part-time work with no expectation that she join his lab. She had little money and survived on ramen noodles. © 1986-2016 The Scientist

Keyword: Sleep
Link ID: 22850 - Posted: 11.10.2016

Ian Sample Science editor US military scientists have used electrical brain stimulators to enhance mental skills of staff, in research that aims to boost the performance of air crews, drone operators and others in the armed forces’ most demanding roles. The successful tests of the devices pave the way for servicemen and women to be wired up at critical times of duty, so that electrical pulses can be beamed into their brains to improve their effectiveness in high pressure situations. The brain stimulation kits use five electrodes to send weak electric currents through the skull and into specific parts of the cortex. Previous studies have found evidence that by helping neurons to fire, these minor brain zaps can boost cognitive ability. The technology is seen as a safer alternative to prescription drugs, such as modafinil and ritalin, both of which have been used off-label as performance enhancing drugs in the armed forces. But while electrical brain stimulation appears to have no harmful side effects, some experts say its long-term safety is unknown, and raise concerns about staff being forced to use the equipment if it is approved for military operations. Others are worried about the broader implications of the science on the general workforce because of the advance of an unregulated technology. © 2016 Guardian News and Media Limited

Keyword: Learning & Memory; Sleep
Link ID: 22844 - Posted: 11.08.2016

Anesthesia during early childhood surgery poses little risk for intelligence and academics later on, the largest study of its kind suggests. The results were found in research on nearly 200,000 Swedish teens. School grades were only marginally lower in kids who'd had one or more common surgeries with anesthesia before age 4, compared with those who'd had no anesthesia during those early years. Whether the results apply to sicker children who have riskier surgeries with anesthesia is not known. But the researchers from Sweden's Karolinska Institute and doctors elsewhere called the new results reassuring, given experiments in young animals linking anesthesia drugs with brain damage. Previous studies of children have been relatively small, with conflicting results. The new findings, published Monday in JAMA Pediatrics, don't provide a definitive answer and other research is ongoing. The study authors and other doctors say the harms from postponing surgery must be considered when evaluating any potential risks from anesthesia in young children. The most common procedures in the study were hernia repairs; ear, nose or throat surgeries; and abdominal operations. The researchers say the operations likely lasted an hour or less. The study did not include children with other serious health problems and those who had more complex or risky operations, including brain, heart and cancer surgeries. The research involved about 33,500 teens who'd had surgery before age 4 and nearly 160,000 who did not. ©2016 CBC/Radio-Canada.

Keyword: Development of the Brain; Sleep
Link ID: 22842 - Posted: 11.08.2016

By CLAIRE CAIN MILLER and AARON E. CARROLL New parents get a lot of advice. It comes from breast-feeding “lactivists” and Ferberizers, attachment parents and anti-helicopter ones. It’s not enough to keep babies fed, rested and changed — they also need to learn grit and sign language. So when the American Academy of Pediatrics recently issued new infant sleep guidelines — highlighting a recommendation that babies sleep in their parents’ rooms for at least six months but ideally a full year — some parents despaired. The academy said that sharing a room could cut babies’ chance of dying in their sleep by “up to 50 percent.” Suffocation, strangulation or sudden infant death syndrome, known as SIDS, kills 3,500 babies a year in this country. The academy’s previous recommendations — place babies on their backs to sleep, without loose bedding, in their own cribs — have been an undisputed success in helping to cut SIDS deaths by 53 percent from 1992 to 2001, but SIDS is still the largest cause of infant mortality in the United States after the first month of life. Yet the recommendation drew skepticism from some doctors, who argued that a close look at the evidence showed that the benefits of room-sharing didn’t always justify its costs to parents, who would have to sacrifice privacy, sex and, above all, sleep. Sharing a room can make breast-feeding and bonding easier. It has historically been common around the world, and many parents do it by choice or necessity. But the evidence is not conclusive, and doctors need to understand the trade-offs before demanding that parents follow the recommendation. Doing so will be part of making parenthood possible in a society in which most parents work, yet receive less government support than in any other industrialized country. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22834 - Posted: 11.05.2016

Bedtime use of cellphones or tablets by children — even just having access to them — is consistently linked to excessive daytime sleepiness and poor sleep, researchers say. They called on teachers, health care professionals, parents and children to be educated about the damaging influence of device use on sleep. The portable media devices have entered the bedroom, giving children unprecedented access to technology and media before researchers have had a chance to explore the positive and negative impacts. To explore whether there's an association between use of, or access to, media devices and sleep quantity and quality, researchers reviewed 20 sleep studies involving 125,198 children aged six to 19. In Monday's issue of JAMA Pediatrics, the reviewers concluded there's strong and consistent evidence of an association between access to or use of devices and reduced sleep quantity (defined as less than 10 hours for children and less than nine hours for adolescents) or quality, as well as increased daytime sleepiness. The way device use leads to poor sleep is thought to be light emission. But the review looked at examples of holding a device in the bedroom and not using it, which excludes light emission as the sole mechanism, said study author Ben Carter of the Institute of Psychiatry, Psychology and Neuroscience at King's College London. "We are presenting results that highlight that it looks likely there are also other causes," Carter said in an email. ©2016 CBC/Radio-Canada.

Keyword: Sleep
Link ID: 22812 - Posted: 11.01.2016

Ramin Skibba Some common swifts spend ten months in flight without taking a break, setting a flight record that would be the envy of Amelia Earhart and Charles Lindbergh. Researchers report these long hauls, which occurred during migrations between Scandinavia and central Africa, on 27 October in Current Biology1. Ornithologists and birdwatchers have speculated about the long-distance prowess of common swifts (Apus apus) since the 1960s. People had seen the birds fill the sky in Liberia, for example, but couldn't find any nearby roost sites where the birds might land. Scientists attached tags that combined tiny data loggers and accelerometers to the 40-gram birds to record their route and flight activity during their annual journey. The team tracked 13 individual birds, some for multiple seasons, starting and ending at their breeding grounds in Sweden. The researchers found that some of the birds made a few brief night landings in winter but remained airborne for 99% of the time. Three birds didn't touch down once in the entire ten months. “These long-term flights confirm what everybody suspected for quite some time now,” says Felix Liechti of the Swiss Ornithological Institute in Sempach. Other birds can remain aloft for long periods. Alpine swifts (Tachymarptis melba) fly nonstop for half the year during their migrations2. And the much larger frigate birds (Fregata minor) off the coast of Ecuador can go for two months without landing while they forage for food in the ocean. They can even sleep on the wing3. But common swifts are in a class of their own. © 2016 Macmillan Publishers Limited,

Keyword: Sleep
Link ID: 22803 - Posted: 10.28.2016

By Steven C. Pan A good night’s sleep can be transformative. Among its benefits are improved energy and mood, better immune system functioning and blood sugar regulation, and greater alertness and ability to concentrate. Given all of these benefits, the fact that a third of the human lifespan is spent sleeping makes evolutionary sense. However, sleep appears to have another important function: helping us learn. Across a plethora of memory tasks—involving word lists, maze locations, auditory tones, and more—going to sleep after training yields better performance than remaining awake. This has prompted many sleep researchers to reach a provocative conclusion: beyond merely supporting learning, sleep is vital, and perhaps even directly responsible, for learning itself. Recent discoveries from neuroscience provide insights into that possibility. Sleep appears to be important for long-term potentiation, a strengthening of signals between neurons that is widely regarded as a mechanism of learning and memory. Certain memories acquired during the day appear to be reactivated and “replayed” in the brain during sleep, which may help make them longer lasting. In some instances the amount of improvement that occurs on memory tasks positively correlates with the length of time spent in certain stages of sleep. These and other findings are generating great excitement among sleep researchers, as well as prompting heated debates about the degree to which sleep may or may not be involved in learning. To date, most sleep and learning research has focused on recall, which is the capacity to remember information. However, new research by Stéphanie Mazza and colleagues at the University of Lyon, recently published in the journal Psychological Science,suggests another potential benefit of sleep: improved relearning. © 2016 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 22787 - Posted: 10.26.2016

Merrit Kennedy Parents can reduce the risk of sudden infant death syndrome by keeping their child's crib in the same room, close to their bed, according to the American Academy of Pediatrics. That's one of the key recommendations in new guidance released today aimed at preventing SIDS, which claims the lives of approximately 3,500 infants every year in the United States. That number "initially decreased in the 1990s after a national safe sleep campaign, but has plateaued in recent years," the AAP adds. The pediatricians say that children should sleep in the same room but on a separate surface from their parents for at least the first six months of their lives, and ideally the first year. They say that this can halve the risk of SIDS. It also "removes the possibility of suffocation, strangulation, and entrapment that may occur when the infant is sleeping in an adult bed," according to the recommendations. The AAP discourages sharing a bed with an infant. You can read the AAP's full guidance here. These are a few more of the pediatricians' recommendations: Infants under a year old should always sleep lying on their backs. Side sleeping "is not safe and is not advised," the AAP says. Infants should always sleep on a firm surface covered by only a flat sheet. That's because soft mattresses "could create a pocket ... and increase the chance of rebreathing or suffocation if the infant is placed in or rolls over to the prone position." Smoking — both during pregnancy and around the infant after birth — can increase the risk of SIDS. Alcohol and illicit drugs during pregnancy can also contribute to SIDS, and "parental alcohol and/or illicit drug use in combination with bed-sharing places the infant at particularly high risk of SIDS," the pediatricians say. © 2016 npr

Keyword: Sleep; Development of the Brain
Link ID: 22786 - Posted: 10.25.2016

Susan Milius For widemouthed, musical midshipman fish, melatonin is not a sleep hormone — it’s a serenade starter. In breeding season, male plainfin midshipman fish (Porichthys notatus) spend their nights singing — if that’s the word for hours of sustained foghorn hums. Males dig trysting nests under rocks along much of North America’s Pacific coast, then await females drawn in by the crooning. New lab tests show that melatonin, familiar to humans as a possible sleep aid, is a serenade “go” signal, says behavioral neurobiologist Ni Feng of Yale University. From fish to folks, nighttime release of melatonin helps coordinate bodily timekeeping and orchestrate after-dark biology. The fish courtship chorus, however, is the first example of the hormone prompting a launch into song, according to Andrew Bass of Cornell University. And what remarkable vocalizing it is. The plainfin midshipman male creates a steady “mmm” by quick-twitching specialized muscles around its air-filled swim bladder up to 100 times per second in chilly water. A fish can extend a single hum for about two hours, Feng and Bass report October 10 in Current Biology. That same kind of super-fast muscle shakes rattle-snake tails and trills vocal structures in songbirds and bats. |© Society for Science & the Public 2000 - 2016

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 22767 - Posted: 10.19.2016

Laura Sanders When the body’s internal sense of time doesn’t match up with outside cues, people can suffer, and not just from a lack of sleep. Such ailments are similar in a way to motion sickness — the queasiness caused when body sensations of movement don’t match the external world. So scientists propose calling time-related troubles, which can afflict time-zone hoppers and people who work at night, “circadian-time sickness.” This malady can be described, these scientists say, with a certain type of math. The idea, to be published in Trends in Neurosciences, is “intriguing and thought-provoking,” says neuroscientist Samer Hattar of Johns Hopkins University. “They really came up with an interesting idea of how to explain the mismatch.” Neuroscientist Raymond van Ee of Radboud University in the Netherlands and colleagues knew that many studies had turned up ill effects from an out-of-whack circadian clock. Depression, metabolic syndromes and memory troubles have been found alongside altered daily rhythms. But despite these results, scientists don’t have a good understanding of how body clocks work, van Ee says. Van Ee and colleagues offer a new perspective by using a type of math called Bayesian inference to describe the circadian trouble. Bayesian inference can be used to describe how the brain makes and refines predictions about the world. This guesswork relies on the combination of previous knowledge and incoming sensory information (SN: 5/28/16, p. 18). In the case of circadian-time sickness, these two cues don’t match up, the researchers propose. |© Society for Science & the Public 2000 - 2016

Keyword: Sleep
Link ID: 22763 - Posted: 10.18.2016