Chapter 14. Biological Rhythms, Sleep, and Dreaming

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by Douglas Main, LiveScience Staff Writer Rock-a-bye owlet, in the treetop … Baby owls and baby mammals, including humans, sleep in an analogous manner, spending a similar amount of time in an awakelike phase called REM (rapid-eye movement), in which dreams are thought to occur, at least during adulthood, new research suggests. In both owls and humans, REM sleep decreases with increasing age. Baby humans spend about 50 percent of their snooze time in this REM phase, whereas that figure decreases to less than 25 percent in adults, according to a statement from the Max Planck Institute for Ornithology. (Applying the REM term to owls, whose eyes are fixed in their heads, may seem a stretch, but researchers use the phrase anyway.) In the new study, published in July in the journal Frontiers in Zoology, the researchers attached electroencephalograms (EEGs) and movement data loggers to 66 young barn owls to record how much time the animals spent in REM sleep and how much they moved while snoozing. They later removed the EEGs, which measure brain waves, and found that the birds mated normally and didn't appear to have suffered any negative effects from the devices, the statement noted. (7 Ways Animals Act Like Humans) "During this sleep phase, the owlets' EEG showed awakelike activity, their eyes remained closed, and their heads nodded slowly," said University of Lausanne researcher Madeleine Scriba in the statement. © 2013 Discovery Communications, LLC.

Keyword: Sleep; Aggression
Link ID: 18534 - Posted: 08.20.2013

By Scicurious It’s something we feel we’ve always known: if you can’t sleep, you need to exercise more. Wear yourself out, make yourself good and tired, you’ll sleep like a baby! So when I started having trouble sleeping, I just figured I needed to work out more. Of course, it kind of figures that often, you have trouble sleeping because of life stress, which often means you’re really busy, which in turn means it probably puts MORE stress in your life just trying to find the time to work out. But that’s just details. So sometimes, when I catch myself constantly waking up in a panic over several days, I’ll fit in some hard exercise. Maybe I’ll go for a long run, or try a really hard new class or something. By the time I go to bed I am WIPED. Physically and mentally. My body is so exhausted that the feeling of lying down is one of total bliss. …so why can’t I SLEEP?!?! Turns out I was suffering under expectations that were a little too high for reality. First off, we’re not wrong. Exercise DOES improve sleep. It does. But not necessarily immediately. And perhaps, instead, we should ask a different question. Instead of asking how exercise impacts sleep, perhaps we should ask how sleep impacts exercise. The authors of this study were looking at exercise and sleep, especially in the elderly. We all sleep less as we get older, but chronic insomnia is a different beast entirely. When we don’t get enough sleep, we get snappish, have trouble concentrating, suffer from daytime sleepiness, and are more susceptible to things like getting sick, or getting in to accidents. © 2013 Scientific American

Keyword: Sleep
Link ID: 18533 - Posted: 08.20.2013

By Brady Dennis, Insomniacs of the world: If you think taking a long run today will make you sleep better tonight, think again. While exercise has long been a prescription for insomnia, new research suggests that exercise doesn’t immediately translate into a better night’s sleep — unless you stick with it for months. A study published Thursday in the Journal of Clinical Sleep Medicine found that aerobic exercise can lead to more rest at night for people who suffer from existing sleep problems, but only if they maintain an exercise regimen for roughly four months. “Exercise isn’t a quick fix. . . . It takes some time and effort,” the study’s lead author, Kelly Glazer Baron, a clinical psychologist and director of the behavioral sleep program at Northwestern University’s Feinberg School of Medicine, said in an interview. “It’s a long-term relationship.” Studies have long suggested that aerobic exercise can contribute to better sleeping habits. But much of the research on the daily effects of exercise on sleep was conducted with healthy sleepers. Tuesday’s study, by contrast, looked at the long-term effects of exercise in people already suffering from sleep disorders. © 1996-2013 The Washington Post

Keyword: Sleep
Link ID: 18526 - Posted: 08.19.2013

NICHOLAS SPITZER is a professor of neuroscience at the University of California. His research concentrates on the ways in which neurons take on specialised functions to enable signalling in the brain. He is editor-in-chief of, a public information service about the brain and nervous system, and is instrumental in the BRAIN Initiative, a research project backed by the White House to advance new technologies to help map the brain. What do you know about the brain that the rest of us don’t? The structure and function of the brain are determined by genes and environment. We think we know this—it’s nature and nurture—but what many don’t realise is that this remains true throughout life. People think the brain is malleable only when we’re young. But that’s just not true. The forms of plasticity we see in the young brain are sustained in the mature brain. By plasticity I mean the ability of the brain to change its structure and function in response to changes in the environment. In addition to the classical ways the brain changes (the strength of the connections, synapses and neurons) we now understand a third kind of brain plasticity in which the neurotransmitter molecules—the signals from one neuron to another—can actually switch. What does this mean for human development? Our experiments have mainly been done on adult rats. A finding that is directly related to the human condition is that putting the animals on different photoperiods [day and night cycles] changes the neurotransmitter identity in the hypothalamus [a part of the brain] and this changes the animal’s behaviour. When animals are on a short day (rats are nocturnal so a short day is good) they make dopamine, the reward chemical. On the long day the neurons switch from dopamine to somatostatin, which retards growth. © The Economist Newspaper Limited 2013.

Keyword: Biological Rhythms
Link ID: 18516 - Posted: 08.17.2013

By KATIE THOMAS The first test for a new sleep drug is — unsurprisingly — how safely it puts people to sleep. Now comes a second test: how safely it lets people wake up. The Food and Drug Administration is taking heightened interest in the issue, as new evidence suggests what many people have long suspected: the effects of common prescription sleep aids like Ambien can persist well into the next day. Of particular concern is whether people who take the drugs before bed can drive safely the next morning. Consumer advocates have warned for years about possible links between sleep drugs and car accidents. In one prominent example, Kerry Kennedy, the former wife of Gov. Andrew M. Cuomo, was arrested last year after tests showed she had taken a sleep aid before swerving her car into a tractor-trailer. The F.D.A.’s actions are part of a robust national conversation about how to cope with the throngs of drivers who take to roads every day under the influence of prescription drugs. Law enforcement authorities have struggled with how to prosecute those who are impaired, especially when they have a prescription. A government survey in 2007 found that nearly 5 percent of daytime drivers tested positive for prescription or over-the-counter medications. Doctors wrote close to 60 million prescriptions for sleep aids in the United States last year, according to the research firm IMS Health, but experts say testing how these drugs affect driving is not easy. Nonetheless, the F.D.A. has been unusually active. Last month, it rejected an application by Merck to approve a new sleep drug, suvorexant, in part because tests showed that some people had trouble driving the next day. In May, the agency warned patients taking common allergy drugs like Benadryl against driving, noting that the sedating effects can sometimes last into the following day. In January, citing similar concerns, the F.D.A. took the unusual step of requiring that all manufacturers of zolpidem, the generic name of Ambien, cut in half the dosage for women. © 2013 The New York Times Company

Keyword: Sleep; Aggression
Link ID: 18508 - Posted: 08.14.2013

By Bahar Gholipour Girls with anorexia may tend to have traits that are usually found in people with autism, a new study suggests. Researchers compared 66 teen girls who had anorexia with about 1,600 girls who did not have the eating disorder, using questionnaires they had previously developed to assess thinking and personality types in children with autism. Girls with the eating disorder anorexia may tend to have traits usually found in people with autism. The girls with anorexia were found to have more interest in systems and order, and lower scores in empathy — a profile more similar to people with autism than to typical adolescents, the researchers said. The finding suggests the two conditions may share certain features, such as rigid attitudes and behaviors, a tendency to be very self-focused and a fascination with detail, the researchers said. “Traditionally, anorexia has been viewed purely as an eating disorder. This is quite reasonable, since the girls’ dangerously low weight and their risk of malnutrition or even death has to be the highest priority” for treatment, said Simon Baron-Cohen, a professor of developmental psychopathology at the University of Cambridge in England. But his study suggests that “underlying the surface behavior, the mind of a person with anorexia may share a lot with the mind of a person with autism,” Baron-Cohen said. People with both conditions have a strong interest in organizational systems; girls with anorexia are intensely interested in the system that governs body weight, shape and food intake, he said. © 1996-2013 The Washington Post

Keyword: Anorexia & Bulimia; Aggression
Link ID: 18497 - Posted: 08.13.2013

Some colors humans are exposed to late at night could cause symptoms of clinical depression. That is the conclusion of a study that builds on previous findings that individuals exposed to dim levels of light overnight, such as from a glowing television set, can develop signs of clinical depression. Investigators, curious as to whether the color of light contributed to depressive symptoms in humans, designed an experiment that exposed hamsters to different colors. They chose hamsters because they are nocturnal, meaning they sleep during the day and are active at night. One group of hamsters was kept in the dark during their nighttime period. Another group of rodents was exposed to blue light and a third group slept in the presence of white light. A fourth group of hamsters was exposed to glowing red light. After four weeks, researchers noted how much sugary water the hamsters drank. The more depressed rodents consumed the least amount of water. Randy Nelson, chair of Ohio State University’s Department of Neuroscience and co-author of the study, said animals that slept in blue and white light appeared to be the most depressed. “What we saw is these animals didn’t show any sleep disruptions at all but they did have mucked up circadian clock genes and they did show depressive phenotypes whereas if they were in the dim red light, they did not,” Nelson said. Nelson explained that photosensitive cells in the retina, which don’t have much to do with vision, detect light and transmit signals to the master circadian clock in the brain that controls the natural sleep-wake cycle.

Keyword: Biological Rhythms; Aggression
Link ID: 18483 - Posted: 08.10.2013

By Bora Zivkovic Sharks are not known for being good at running in running wheels. Or hopping from one perch to the other in a birdcage. Which is why, unlike hamsters or sparrows, sharks were never a very popular laboratory model for circadian research. The study of fish came late into the field of chronobiology due to technical difficulties of monitoring rhythms, at the time when comparative tradition was starting to make way to the more focused approach on choice model organisms – in this case, the zebrafish. But the comparative tradition was always very strong in the field. Reading the old papers (especially review papers and loooong theoretical papers) by the pioneers like Jurgen Asschoff and Colin Pittendrigh, it seems like researchers at the time were just going around and saying “let me try this species…and this one…and this one…”. And there were good reasons for this early approach. At the time, it was not yet known how widespread circadian rhythms were – it is this early research that showed they are ubiqutous in all organisms that live at or close to the surface of the earth or ocean. Another reason for such broad approach to testing many species was to find generalities – the empirical generalizations (e.g,. the Aschoff’s Rules) that allowed the field to get established, and that provided a template for the entire research program, including refining the proper experimental designs. © 2013 Scientific American

Keyword: Biological Rhythms
Link ID: 18474 - Posted: 08.08.2013

By ANAHAD O'CONNOR Losing sleep tends to make people eat more and gain weight, and now a new study suggests that one reason may be the impact that sleep deprivation has on the brain. The research showed that depriving people of sleep for one night created pronounced changes in the way their brains responded to high-calorie junk foods. On days when the subjects had not had proper sleep, fattening foods like potato chips and sweets stimulated stronger responses in a part of the brain that helps govern the motivation to eat. But at the same time, the subjects experienced a sharp reduction in activity in the frontal cortex, a higher-level part of the brain where consequences are weighed and rational decisions are made. The findings suggested that one unfortunate result of sleep loss is this “double hit” in brain activity, said Matthew P. Walker, an author of the study and a professor of psychology and neuroscience at the University of California, Berkeley. A sleepy brain appears to not only respond more strongly to junk food, but also has less ability to rein that impulse in. Some experts have theorized that in a sleep-deprived state, people eat more food simply to make up for all the calories they expend as they burn the midnight oil. But the new study showed that the changes in brain activity were evident even when the subjects were fed extra food and not experiencing any increased sensations in hunger. “Their hunger was no different when they were sleep deprived and when they had a normal night of sleep,” Dr. Walker said. “That’s important because it suggests that the changes we’re seeing are caused by sleep deprivation itself, rather than simply being perhaps more metabolically impaired when you’re sleep deprived.” Copyright 2013 The New York Times Company

Keyword: Sleep; Aggression
Link ID: 18471 - Posted: 08.07.2013

By Meghan Rosen A short camping trip could help people rise and shine. After a week living in tents in Colorado’s Rockies, volunteers’ internal clocks shifted about two hours earlier, transforming night owls into early birds, researchers report August 1 in Current Biology. “It’s a clever study, and it makes a dramatic point,” says Katherine Sharkey, a sleep researcher and physician at Brown University. People get much more light outside than they do indoors, and that can reset their internal clocks, she says. A master clock in the brain controls the release of melatonin, a hormone that prepares the body for sleep. Melatonin levels rise in the early evening and then taper off in the morning before a person wakes up. But because so many people spend their days indoors and their nights bathed in the glow of electric lights, the body’s clock can get out of sync. Melatonin levels ramp up later in the evening and ebb later in the morning — often after a person has woken up. The lingering sleep hormone can make people groggy. Kenneth Wright Jr., a sleep researcher at the University of Colorado Boulder, and colleagues whisked eight volunteers away from artificial lights for a summer camping trip. After nightfall, the campers used only campfires for illumination — no flashlights (or cellphones) allowed. © Society for Science & the Public 2000 - 2013

Keyword: Biological Rhythms
Link ID: 18445 - Posted: 08.03.2013

Sleepless night, the moon is bright. People sleep less soundly when there's a full moon, researchers discovered when they analyzed data from a past sleep study. If you were tossing and turning and howling at your pillow this week, you’re not necessarily a lunatic, at least in the strictest sense of the word. The recent full moon might be to blame for your poor sleep. In the days close to a full moon, people take longer to doze off, sleep less deeply, and sleep for a shorter time, even if the moon isn’t shining in their window, a new study has found. “A lot of people are going to say, ‘Yeah, I knew this already. I never sleep well during a full moon.’ But this is the first data that really confirms it,” says biologist Christian Cajochen of the University of Basel in Switzerland, lead author of the new work. “There had been numerous studies before, but many were very inconclusive.” Anecdotal evidence has long suggested that people’s sleep patterns, moods, and even aggression is linked to moon cycles. But past studies of potential lunar effects have been tainted by statistical weaknesses, biases, or inconsistent methods, Cajochen says. Between 2000 and 2003, he and his colleagues had collected detailed data on the sleep patterns of 33 healthy volunteers for an unrelated study on the effects of aging on sleep. Using electroencephalograms (EEG) that measure brain activity, they recorded how deep and how long each participant’s nightly sleep was in a controlled, laboratory setting. Years after the initial experiment, the scientists were drinking in a pub—during a full moon—and came up with the idea of going back to the data to test for correlations with moon cycles. © 2012 American Association for the Advancement of Science.

Keyword: Sleep; Aggression
Link ID: 18415 - Posted: 07.27.2013

By Scicurious We all know we should get more sleep, we’re just not very good at it. In fact, we’re so BAD at it that 28.3% of us (as of 2007, anyway) got less than 6 hours of sleep per night. Really, are we surprised? After all, there are kids that wake up in the night, stress that keeps us awake, always more things to do, multiple jobs, and only so many hours in the day. But that lack of sleep can have some not so great effects on our bodies. It decreases things like cognitive performance, increases anxiety, and…it’s not good for our waistlines. Sleep loss is associated with higher caloric intake, when you can’t sleep you eat. But does this increased caloric intake translate to weight gain? The biggest positive point of this study on sleep restriction was how LARGE it was. When doing human studies that are not large scale surveys (which usually involve phone calls or mail in or online and therefore are less expensive) it costs a LOT of money to bring some people in to the lab to do nothing but hang out and sleep for a week, especially if you are watching for things like food intake (and controlling what they eat). I’m very pleased that they got these numbers, 225 people! The authors took these 225 people, and brought them into the lab. They got two baseline nights (to see how much they naturally slept), 5 sleep restriction nights, and then another 2 recovery nights. But unfortunately, they did not balance the control and sleep restriction, where they were restricted down to FOUR HOURS a night of sleep (ick). They only had 27 controls out of all of these (people allowed to sleep fully all the nights of the study), the rest were sleep restriction. I have to wonder why they did it this way. While the two original nights and the two recovery nights could in theory serve as a partial control, I don’t think that those would work. After all, if most people are slightly sleep restricted, the original two nights will be recovery as well, and both sets of recovery nights may not be representative of optimal sleep. © 2013 Scientific American

Keyword: Sleep; Aggression
Link ID: 18402 - Posted: 07.23.2013

By Scicurious It seems like the worst sort of cycle. The less sleep you get, the less effective you are. Then you have more to do, get more stressed, and stay up trying to get it all done (or lie awake stressing about it). The next day, less sleep, and even more anxiety. The ironic part is that you might not be quite so anxious…if you could just get some SLEEP. The authors of this study wanted to look at anxiety responses in people, and how they were affected by lack of sleep. To do this, you need 19 healthy participants, an fMRI machine, a test of anxiety…and way to keep people up all night. How do you assess anxiety responses? Start with cues, and then give outcomes. You can see the layout of the studies above. The participants were placed in an fMRI scanner. During the recording, they were shown signs, followed by stimuli. If they got a negative sign, they would always get a negative stimuli (a man with a gun, which is plenty good enough to provoke an anxiety response). If they got a zero sign, they got a normal stimuli (a doorknob. Nothing scary there). If they got a question mark, they have a 50% chance of getting the negative stimulus. This question mark gives you an ambiguous stimulus, you don’t know what to expect. They had the participants go through the series of stimuli in two conditions: rested and sleep deprived. And when they sleep deprived them, BOY did they. Many sleep deprivation studies will restrict sleep to, say, 4 hours the night before the study, or 5. Not these guys. No, they had the participants pull an all-nighter! © 2013 Scientific American

Keyword: Sleep; Aggression
Link ID: 18379 - Posted: 07.16.2013

by Kelly Servick It almost seems like a mystical correlation. Babies conceived at certain times of the year appear healthier than those conceived during other times. Now, scientists have shown that the bizarre phenomenon is actually true—and they think they may know why it happens. The work is "a really long-overdue analysis," says economist Douglas Almond of Columbia University, who was not involved in the study. "This is maybe not quite a smoking gun," he says, "but it's much stronger than the previous evidence." As early as the 1930s, researchers noticed that children born in winter were more prone to health problems later in life: slower growth, mental illness, and even early death. Among the proposed explanations were diseases, harsh temperatures, and higher pollution levels associated with winter, when those expectant mothers and near-term fetuses might be most vulnerable. But recently, as economists looked at demographics, the picture got more complicated. Mothers who are nonwhite, unmarried, or lack a college education are more likely to have children with health and developmental problems. They are also more likely to conceive in the first half of the year. That made it hard to tease out the socioeconomic effects from the seasonal ones. Economists Janet Currie and Hannes Schwandt of Princeton University took a new approach to resolving this long-standing question, using data from the vital statistics offices in New Jersey, New York, and Pennsylvania about births between 1994 and 2006. To control for socioeconomic status, their study looked only at siblings born to the same mother. And lo and behold, seasonal patterns persist, they report online today in the Proceedings of the National Academy of Sciences. © 2010 American Association for the Advancement of Science

Keyword: Biological Rhythms; Aggression
Link ID: 18363 - Posted: 07.09.2013

By Michelle Roberts Health editor, BBC News online Late nights and lax bedtime routines can blunt young children's minds, research suggests. The findings on sleep patterns and brain power come from a UK study of more than 11,000 seven-year-olds. Youngsters who had no regular bedtime or who went to bed later than 21:00 had lower scores for reading and maths. Lack of sleep may disrupt natural body rhythms and impair how well the brain learns new information say the study authors. They gathered data on the children at the ages of three, five and then seven to find out how well they were doing with their learning and whether this might be related to their sleeping habits. Erratic bedtimes were most common at the age of three, when around one in five of the children went to bed at varying times. By the age of seven, more than half the children had a regular bedtime of between 19:30 and 20:30. Overall, children who had never had regular bedtimes tended to fare worse than their peers in terms of test scores for reading, maths and spatial awareness. The impact was more obvious throughout early childhood in girls than in boys and appeared to be cumulative. BBC © 2013

Keyword: Sleep; Aggression
Link ID: 18362 - Posted: 07.09.2013

Melatonin is marketed as a natural sleep aid but it's potentially risky for healthy children to use long term, Canadian pediatricians say. Difficulties settling, falling asleep and staying asleep affect up to 25 per cent of children generally and up to half of those with physical and mental health problems, according to the Canadian Sleep Society. Melatonin is a hormone of darkness that is part of the sleep cycle. People can buy melatonin supplements at pharmacies and health food stores to overcome jet lag or occasional insomnia. But long-term use by healthy, developing children isn't advised, said Dr. Shelly Weiss, a neurologist at the Hospital for Sick Children in Toronto, who is studying the use of melatonin supplements for improving sleep in children with epilepsy. "It's being touted as this magic pill," said Weiss. "There's definitely concern that people are going to use it more widely and not appreciate that their child can learn to sleep better without a hormone being given." Melatonin supplements contain between 25 to 50 times as much melatonin as the body makes at night, Weiss noted. "There's definitely potential risk, mostly to delayed puberty or delayed development in children who have taken it for a long time," said Weiss, who is also president of the Canadian Sleep Society and an associate professor at the University of Toronto. © CBC 2013

Keyword: Sleep; Aggression
Link ID: 18354 - Posted: 07.08.2013

A UC Berkeley study suggests that sleep deprivation triggers anxiety by inducing hyperactivity in brain regions that control emotions. The study, published in the Journal of Neuroscience, suggests that sleep therapy can help patients with anxiety disorders. Stress and anticipation bring anxiety that can sometimes be good; if under control, anxiety might help a person focus and be more efficient. But a patient with anxiety disorders, such as post-traumatic stress disorder (PTSD), generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD) or other disorders and phobias, cannot control it. The feeling of anxiety and nervousness is constant and has major negative impact on their everyday life. The socioeconomic impact is huge as about one in five adults in the U.S. are affected by such mental illnesses. What are the drivers of anxiety disorders? Why can some people control anxiety while others cannot? Research studies have shown over the years that causes can be genetics, personality, social environment and brain chemistry. Scientists have found a network of neurons in the brain that supports affective anticipation and anxiety. More precisely, those with anxiety disorders have hyperactivity in certain regions of the brain that process emotions, including the amygdala and anterior insula cortex. On top of that, sleep deprivation amplifies the symptoms, a setback for patients because it is very common for them to suffer from sleep abnormalities. Looking for more clues about the connection between sleep and anxiety management, Matthew P. Walker, professor of psychology and neuroscience at UC Berkeley, led a study that looked for differences in the activity of the amygdala and anterior insula cortex in the brains of healthy adults after sleep deprivation and after a good night’s sleep.

Keyword: Sleep; Aggression
Link ID: 18345 - Posted: 07.04.2013

Till Roenneberg Sleep is essential for health, performance and wellbeing. Yet in many countries, people are getting one to two hours less of it each night than their ancestors did 50–100 years ago. Even when people have the opportunity to sleep, many cannot. Sleep pathologies are approaching epidemic levels, affecting an estimated 70 million people in the United States alone (see And in some countries, direct and indirect costs of sleep-related problems are thought to approach 1% of gross domestic product1. Despite these alarming numbers, sleep research ranks only 91st in the 235 categories on this year's funding list of the US National Institutes of Health — below, for instance, studies of tobacco (see Researchers have made great advances in understanding which neurotransmitters and brain regions are involved in sleep2, and how the timings of sleep and wakefulness are controlled by an internal (circadian) clock3, among other things. Yet we still do not have answers to the most basic questions. It is not really understood, for instance, what sleep is for, how much is optimal, how sleep quality can be measured and predicted, or the role of genetic and environmental factors in determining ideal sleeping patterns. One reason for this lack of understanding is that most of what is known about sleep comes from laboratory studies. Subjects in these studies tend to be mice or hamsters that are kept in artificial light–dark cycles, or people who have been instructed to sleep at certain times in beds that are not their own, with electrodes fastened to their heads. Assessments of sleep are also often based on subjective responses to questions about how 'well' people feel after they have slept, or whether they think they experienced a good night's sleep. To learn about sleep in the real world, and to establish how to manage sleep to improve productivity, health and quality of life, we need a multidisciplinary 'human sleep project'. © 2013 Nature Publishing Group

Keyword: Sleep; Aggression
Link ID: 18325 - Posted: 06.29.2013

By Susan Milius After 17 years underground, throngs of ruby-eyed cicadas clawed up through the soil this year to partake in a once-in-a-lifetime, synchronized mating frenzy. Except it wasn’t one big insect orgy: It was three. The insects that unearthed themselves to breed in 2013 belong to three distinct species. You need only flip them over to see some differences, written in the varieties of their orange markings. You can hear the differences too, says Chris Simon of the University of Connecticut in Storrs. The tymbals on either side of a male’s abdomen vibrate to make the racket for which cicadas are famous. A chorus of courting Magicicada cassini males sounds like an electric carving knife revving up. M. septendecula coughs out a series of rasps. And M. septendecim serenades with the whistling drone of a B-movie spaceship. The various thrums and buzzings may mingle in the same neighborhood, but the last time ancestors of these species mated with each other was almost 4 million years ago, Simon says. That’s the conclusion of the most detailed genetic studies yet of periodical cicada evolutionary history, which Simon and colleagues published in April in the Proceedings of the National Academy of Sciences. With DNA plus episodic field observations, the scientists are getting an idea about the odd family tree of periodical cicadas, how the insects synchronize their life cycles and why they breed side-by-side with others unsuitable for mating. © Society for Science & the Public 2000 - 2013

Keyword: Biological Rhythms; Aggression
Link ID: 18321 - Posted: 06.29.2013

By DAVID DOBBS On average, about 700 Americans kill themselves each week — but in the fine-weather weeks of May and June, the toll rises closer to 800, sometimes higher. Every year, suicide peaks with the tulips and lilacs — increasing roughly 15 percent over the annual average to create one of psychiatry’s most consistent epidemiological patterns. It may seem perverse that the period of spring and early summer, as the psychologist Kay Redfield Jamison puts it in her splendid book “Night Falls Fast,” should contain “a capacity for self-murder that winter less often has.” Yet it does. This grim spring growth confounds conventional belief that suicides peak in winter. It also confounds researchers — and fascinates them. As they discover more angles into the biology of mood and behavior, they are finding new clues about why suicides rise with the sun’s arc. They hope solving this puzzle will help us better understand why people commit suicide at all — and perhaps reduce the numbers year-round. This effort takes an extra urgency from what Dr. Adam Kaplin, a psychiatrist at Johns Hopkins University, calls a “suicide epidemic” — a sharp increase in both absolute and per-capita rates since the recession that began in 2007, particularly among the middle-aged. More than 38,000 people committed suicide in the United States in 2010 — a 16.5 percent jump from the 32,600 suicides five years before, and a new high. The stakes involved in figuring out the dynamics of self-murder seem only to rise with time. The spring surge in suicides is actually the largest of a few oscillations throughout the year. After dropping to an annual low in February (October in the southern hemisphere), rates climb sharply through spring; fall slowly in summer; show a slight rise, according to some studies, in fall; and then begin a steep winter drop. The spring peak generally runs 10 to 25 percent above the yearly average and 20 to 50 percent above the February low. Copyright 2013 The New York Times Company

Keyword: Depression; Aggression
Link ID: 18308 - Posted: 06.25.2013