Chapter 14. Biological Rhythms, Sleep, and Dreaming
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
Aylin Woodward Fearful, flighty chickens raised for eating can hurt themselves while trying to avoid human handlers. But there may be a simple way to hatch calmer chicks: Shine light on the eggs for at least 12 hours a day. Researchers at the University of California, Davis bathed eggs daily in light for different time periods during their three-week incubation. When the chickens reached 3 to 6 weeks old, the scientists tested the birds’ fear responses. In one test, 120 chickens were randomly selected from the 1,006-bird sample and placed one by one in a box with a human “predator” sitting visibly nearby. The chickens incubated in light the longest — 12 hours — made an average of 179 distress calls in three minutes, compared with 211 from birds incubated in complete darkness, animal scientists Gregory Archer and Joy Mench report in January in Applied Animal Behaviour Science. Chickens exposed to lots of light as eggs “would sit in the closest part of the box to me and just chill out,” Archer says. The others spent their time trying to get away. How light has its effect is unclear. On commercial chicken farms, eggs typically sit in warm, dark incubation rooms. The researchers are now testing light's effects in large, commercial incubators. Using light exposure to raise less-fearful chickens could reduce broken bones during handling at processing plants, Archer says. It might also decrease harmful anxious behaviors, such as feather pecking of nearby chickens. G. S. Archer and J. A. Mench. Exposing avian embryos to light affects post-hatch anti-predator fear responses. Applied Animal Behaviour Science. Vol. 186, January 2017, p. 80. doi: 10.1016/j.applanim.2016.10.014. © Society for Science & the Public 2000 - 2016
Ah, to sleep, perchance … to shrink your neural connections? That's the conclusion of new research that examined subtle changes in the brain during sleep. The researchers found that sleep provides a time when thebrain's synapses — the connections among neurons—shrink back by nearly 20 percent. During this time, the synapses rest and prepare for the next day, when they will grow stronger while receiving new input—that is, learning new things, the researchers said. Without this reset, known as "synaptic homeostasis," synapses could become overloaded and burned out, like an electrical outlet with too many appliances plugged in to it, the scientists said. "Sleep is the perfect time to allow the synaptic renormalization to occur … because when we are awake, we are 'slaves' of the here and now, always attending some stimuli and learning something," said study co-author Dr. Chiara Cirelli of the University of Wisconsin-Madison Center for Sleep and Consciousness. "During sleep, we are much less preoccupied by the external world … and the brain can sample [or assess] all our synapses, and renormalize them in a smart way," Cirelli told Live Science. Cirelli and her colleague, Dr. Giulio Tononi, also of the University of Wisconsin-Madison, introduced this synaptic homeostasis hypothesis (SHY) in 2003. © 2017 Scientific American
Carl Zimmer Over the years, scientists have come up with a lot of ideas about why we sleep. Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators. A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day. In order to learn, we have to grow connections, or synapses, between the neurons in our brains. These connections enable neurons to send signals to one another quickly and efficiently. We store new memories in these networks. In 2003, Giulio Tononi and Chiara Cirelli, biologists at the University of Wisconsin-Madison, proposed that synapses grew so exuberantly during the day that our brain circuits got “noisy.” When we sleep, the scientists argued, our brains pare back the connections to lift the signal over the noise. In the years since, Dr. Tononi and Dr. Cirelli, along with other researchers, have found a great deal of indirect evidence to support the so-called synaptic homeostasis hypothesis. It turns out, for example, that neurons can prune their synapses — at least in a dish. In laboratory experiments on clumps of neurons, scientists can give them a drug that spurs them to grow extra synapses. Afterward, the neurons pare back some of the growth. Other evidence comes from the electric waves released by the brain. During deep sleep, the waves slow down. Dr. Tononi and Dr. Cirelli have argued that shrinking synapses produce this change. © 2017 The New York Times Company
Ian Sample Science editor As an antidote to one of the ills of modern life, it may leave some quite cold. When the lure of the TV or fiddling on the phone keep you up late at night, it is time to grab the tent and go camping. The advice from scientists in the US follows a field study that found people fell asleep about two hours earlier than usual when they were denied access to their gadgets and electrical lighting and packed off to the mountains with a tent. A weekend in the wilds of the Rocky Mountains in Colorado helped reset people’s internal clocks and reversed the tendency of artificial light to push bedtime late into the night. A spell outdoors, the researchers conclude, could be just the thing for victims of social jetlag who find themselves yawning all day long. “Our modern environment has really changed the timing of our internal clocks, but also the timing of when we sleep relative to our clock,” said Kenneth Wright, director of the sleep and chronobiology lab at the University of Colorado in Boulder. “A weekend camping trip can reset the clock rapidly.” To explore the sleep-altering effects of the natural environment, Wright sent five hardy colleagues, aged 21 to 39, on a six day camping trip to the Rocky Mountains one December. They left their torches and gadgets behind, and had only sunlight, moonlight and campfires for illumination. The campers went to bed on average two and a half hours earlier than they did at home, and racked up nearly 10 hours of sleep per night compared with their usual seven and a half hours. Monitors showed that they were more active in the daytime and were exposed to light levels up to 13 times higher than they typically received at home.
Bruce Bower Hunter-gatherers and farming villagers who live in worlds without lightbulbs or thermostats sleep slightly less at night than smartphone-toting city slickers, researchers say. “Contrary to conventional wisdom, people in societies without electricity do not sleep more than those in industrial societies like ours,” says UCLA psychiatrist and sleep researcher Jerome Siegel, who was not involved in the new research. Different patterns of slumber and wakefulness in each of these groups highlight the flexibility of human sleep — and also point to potential health dangers in how members of Western societies sleep, conclude evolutionary biologist David Samson of Duke University and colleagues. Compared with other primates, human evolution featured a shift toward sleeping more deeply over shorter time periods, providing more time for learning new skills and knowledge as cultures expanded, the researchers propose. Humans also evolved an ability to revise sleep schedules based on daily work schedules and environmental factors such as temperature. Samson’s team describes sleep patterns in 33 East African Hadza hunter-gatherers over a total of 393 days in a paper published online January 7 in the American Journal of Physical Anthropology. The team’s separate report on slumber among 21 rural farmers in Madagascar over 292 days will appear later this year in the American Journal of Human Biology. |© Society for Science & the Public 2000 - 201
By Rachael Lallensack Jet lag can put anyone off their game, even Major League Baseball (MLB) players. Long-distance travel can affect specific—and at times, crucial—baseball skills such as pitching and base running, a new study finds. In fact, jetlag's effects can even cancel out the home field advantage for some teams returning from away games. Jet lag is known for its fatigue-inducing effects, most of which stem from a mismatch between a person’s internal clock and the time zone he or she is in, something called “circadian misalignment.” This misalignment is especially strong when a person’s day is shorter than it should be—which happens whenever people travel east—previous research has shown. Just how that affects sports teams has long been debated. A 2009 study of MLB, for example, found that jet lag did decrease a team’s likelihood of winning, if only slightly. But no prior study has ever been able to pinpoint exact areas of game play where the effects of jet lag hit hardest—data that could help coaches and trainers better prepare players for games following travel. To figure out how that might happen, “adopted” Chicago Cubs fan and study author Ravi Allada, a neurobiologist at Northwestern University in Evanston, Illinois, looked at 20 years’ worth of MLB data from 1992 to 2011. He and his team narrowed their data set from 46,535 games to the 4919 games in which players traveled at least two time zones. Then, they broke down offensive and defensive stats from each of those games, including home runs allowed, stolen bases, and sacrifice flies. Finally, they compared how the numbers changed for teams that had traveled east versus those that had traveled west. © 2017 American Association for the Advancement of Science.
Keyword: Biological Rhythms
Link ID: 23140 - Posted: 01.24.2017
by Laura Sanders Most nights I read a book in bed to wind down. But when I run out of my library supply, I read articles on my phone instead. I suspect that this digital substitution messes with my sleep. That’s not good for me — but it’s probably worse for the many children who have screens in their rooms at night. A team of researchers recently combed through the literature looking for associations between mobile devices in the bedroom and poor sleep. Biostatistician Ben Carter of King’s College London and colleagues found that kids between ages 6 and 19 who used screen-based media around bedtime slept worse and were more tired in the day. That’s not surprising: Phones, tablets and laptops make noise and emit blue light that can interfere with the sleep-inducing melatonin. But things got interesting when the researchers compared kids who didn’t have screens in their bedrooms with kids who did have phones or tablets in their rooms but didn’t use them. You might think there wouldn’t be a sleep difference between those groups. None of these kids were up all night texting, gaming or swiping, so neither sounds nor blue light were messing with any of the kids’ sleep. Yet Carter and colleagues found a difference: Kids who had screen-based media in their bedroom, but didn’t use it, didn’t sleep as much as kids without the technology. What’s more, the sleep they did get was worse and they were more tired during the day, the researchers reported in the December JAMA Pediatrics. |© Society for Science & the Public 2000 - 2017
Children who have their tonsils removed to treat chronic throat infections or breathing problems during sleep may get more short-term symptom relief than similar children who don’t get tonsillectomies, two recent studies suggest. Over time, however, the benefits of surgery for chronic streptococcal throat infections appear to go away. Three years after tonsillectomies, children who had these procedures had about the same number of throat infections as those who didn’t get their tonsils taken out, one of the studies in the journal Pediatrics found. “Tonsillectomy, while very common and generally safe, is not completely without risk,” said Sivakumar Chinnadurai, senior author of the strep throat study and a researcher at Vanderbilt University Medical Center in Nashville. “The recognition of risks, and the knowledge that some patients’ infection rate improves over time has led to [strep] infection being a much less common indication for tonsillectomy than it was in the past,” Chinnadurai added by email. “While tonsillectomy remains one of the most common surgeries performed in the United States, the main indication for children has switched to obstructed breathing.” To assess the potential for tonsillectomies to help young people with chronic strep infections, Chinnadurai and colleagues examined data from seven studies of children who had experienced at least three strep infections in the previous one to three years. © 1996-2017 The Washington Post
Link ID: 23127 - Posted: 01.21.2017
By JANE E. BRODY Insomnia is like a thief in the night, robbing millions — especially those older than 60 — of much-needed restorative sleep. As the king laments in Shakespeare’s “Henry IV, Part 2”: O sleep, O gentle sleep, Nature’s soft nurse, how have I frightened thee. That thou no more will weigh my eyelids down, And steep my senses in forgetfulness? The causes of insomnia are many, and they increase in number and severity as people age. Yet the problem is often overlooked during routine checkups, which not only diminishes the quality of an older person’s life but may also cause or aggravate physical and emotional disorders, including symptoms of cognitive loss. Most everyone experiences episodic insomnia, a night during which the body seems to have forgotten how to sleep a requisite number of hours, if at all. As distressing as that may seem at the time, it pales in comparison to the effects on people for whom insomnia — difficulty falling asleep, staying asleep or awakening much too early — is a nightly affair. A survey done in 1995 by researchers at the National Institute on Aging among more than 9,000 people aged 65 and older living in three communities revealed that 28 percent had problems falling asleep and 42 percent reported difficulty with both falling asleep and staying asleep. The numbers affected are likely to be much larger now that millions spend their pre-sleep hours looking at electronic screens that can disrupt the body’s biological rhythms. Insomnia, Dr. Alon Y. Avidan says, “is a symptom, not a diagnosis” that can be a clue to an underlying and often treatable health problem and, when it persists, should be taken seriously. Dr. Avidan is director of the sleep clinic at the University of California, Los Angeles, David Geffen School of Medicine. © 2017 The New York Times Company
By Alan Burdick Some nights—more than I like, lately—I wake to the sound of the bedside clock. The room is dark, without detail, and it expands in such a way that it seems as if I’m outdoors, under an empty sky, or underground, in a cavern. I might be falling through space. I might be dreaming. I could be dead. Only the clock moves, its tick steady, unhurried. At these moments I have the most chilling understanding that time moves in only one direction. I’m tempted to look at the clock, but I already know that it’s the same time it always is: 4 A.M., or 4:10 A.M., or once, for a disconcerting stretch of days, 4:27 A.M. Even without looking, I could deduce the time from the ping of the bedroom radiator gathering steam in winter or the infrequency of the cars passing by on the street outside. In 1917, the psychologist Edwin G. Boring and his wife, Lucy, described an experiment in which they woke people at intervals to see if they knew what time it was; the average estimate was accurate to within fifty minutes, although almost everyone thought it was later than it actually was. They found that subjects were relying on internal or external signals: their degree of sleepiness or indigestion (“The dark brown taste in your mouth is never bad when you have been asleep only a short time”), the moonlight, “bladder cues,” the sounds of cars or roosters. “When a man is asleep, he has in a circle round him the chain of the hours, the sequence of the years, the order of the heavenly bodies,” Proust wrote. “Instinctively he consults them when he awakes, and in an instant reads off his own position on the earth’s surface and the time that has elapsed during his slumbers.” © 2017 Condé Nast.
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
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
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
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.
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
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.
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
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
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.
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.