Links for Keyword: Biological Rhythms

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By Krystnell A. Storr This one goes out to the head bobbers, the window seat sleepers, and the open-mouth breathers — there is no shame in being able to fall asleep anywhere, and at any time. Be proud, and, if you can’t help it, snore loud. Scientists have come to a consensus that our bodies definitely need sleep, but we don’t all need the same amount. The next step for them is to figure out where the process of sleep starts and ends in the body. And, like a good movie, one revelation about sleep only leads to another. Think of yourself as a very minor character in the scientific story of fatigue. The real star of this cozy mystery is the fruit fly, an A-lister in sleep science. Thanks to fruit flies, we understand two of the basic factors that govern sleep: a biological clock, which scientists know a lot about, and a homeostatic switch, which they only just discovered and are beginning to understand. Let’s start with this biological clock. The clock that is connected to sleep is controlled by a circadian rhythm and uses environmental cues such as sunlight to tell the body when to wake up. This sun-sleep connection in humans and flies alike got scientists like Russell Foster, a professor at Oxford University in the United Kingdom, asking questions such as: What happens when we don’t have the mechanisms in our eye to distinguish dawn from dusk and send that message to the brain? Why can we still fall asleep according to the circadian rhythm? The answer, Foster said, is that mammals have a third layer of photoreceptors in the eye. It used to be that scientists thought rods and cones, cells that help us process images, were the only ones in the eye that worked to detect light. But when they removed these cells in mice, they noticed that the mice could still keep up with the circadian rhythm. The hidden cells, they found, were intrinsically sensitive to light and acted as a backup measure to keep us on our sleep schedule, whether we can see that the sun is up or not.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22656 - Posted: 09.15.2016

By Sunpreet Singh Every day people are exposed to hours of artificial light from a variety of sources – computers, video games, office lights and, for some, 24-hour lighting in hospitals and nursing homes. Now new research in animals shows that excessive exposure to “light pollution” may be worse for health than previously known, taking a toll on muscle and bone strength. Researchers at Leiden University Medical Center in the Netherlands tracked the health of rats exposed to six months of continuous light compared to a control group of rats living under normal light-dark conditions — 12 hours of light, followed by 12 hours of dark. During the study, the rats exposed to continuous light had less muscle strength and developed signs of early-stage osteoporosis. They also got fatter and had higher blood glucose levels. Several markers of immune system health also worsened, according to the report published in the medical journal Current Biology. While earlier research has suggested excessive light exposure could affect cognition, the new research was surprising in that it showed a pronounced effect on muscles and bones. While it’s not clear why constant light exposure took a toll on the motor functions of the animals, it is known that light and dark cues influence a body’s circadian rhythms, which regulate many of the body’s physiological processes. “The study is the first of its kind to show markers of negatively-affected muscle fibers, skeletal systems and motor performances due to the disruption of circadian clocks, remarkably in only a few months,” said Chris Colwell, a psychiatry professor and sleep specialist at the University of California, Los Angeles, who was not part of the study. “They found that not only did motor performance go down on tests, but the muscles themselves just atrophied, and mice physically became weaker under just two months under these conditions.” © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22556 - Posted: 08.13.2016

By JOANNA KLEIN Jet lag may be the worst part of traveling. And it hits many people harder traveling east than west. Why they feel this way is unclear. But scientists recently developed a model that mimics special time-keeping cells in the body and offers a mathematical explanation for why traveling from west to east feels so much worse. It also offers insights on recovering from jet lag. Deep inside the brain, in a region called the hypothalamus (right above where our optic nerves cross) the internal clock is ticking. And approximately every 24 hours, 20,000 special pacemaker cells that inhabit this area, known as the superchiasmatic nucleus, synchronize, signaling to the rest of the body whether it’s night or day. These cells know which signal to send because they receive light input from our environments — bright says wake, dark says sleep. But when you travel across multiple time zones, like flying from New York to Moscow, those little pacemaker cells that thought they knew the routine scramble around confused before they can put on their show. The whole body feels groggy because it’s looking for the time and can’t find it. The result: jet lag. Most of our internal clocks are a little bit slow, and in the absence of consistent light cues — like when you travel across time zones — the pacemaker cells in your body want to have a longer day, said Michelle Girvan, a physicist at the University of Maryland who worked on the model published in the journal Chaos on Tuesday. “This is all because the body’s internal clock has a natural period of slightly longer than 24 hours, which means that it has an easier time traveling west and lengthening the day than traveling east and shortening the day,” Dr. Girvan said. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22446 - Posted: 07.16.2016

Rebecca Boyle Eliane Lucassen works the night shift at Leiden University Medical Center in the Netherlands, beginning her day at 6 p.m. Yet her own research has shown that this schedule might cause her health problems. “It’s funny,” the medical resident says. “Here I am, spreading around that it’s actually unhealthy. But it needs to be done.” Lucassen and Johanna Meijer, a neuroscientist at Leiden, report today in Current Biology1 that a constant barrage of bright light prematurely ages mice, playing havoc with their circadian clocks and causing a cascade of health problems. Mice exposed to constant light experienced bone-density loss, skeletal-muscle weakness and inflammation; restoring their health was as simple as turning the lights off. The findings are preliminary, but they suggest that people living in cities flooded with artificial light may face similar health risks. “We came to know that smoking was bad, or that sugar is bad, but light was never an issue,” says Meijer. “Light and darkness matter.” Disrupted patterns Many previous studies have hinted at a connection between artificial light exposure and health problems in animals and people2. Epidemiological analyses have found that shift workers have an increased risk of breast cancer3, metabolic syndrome4 and osteoporosis5, 6. People exposed to bright light at night are more likely to have cardiovascular disease and often don’t get enough sleep. © 2016 Macmillan Publishers Limited,

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22442 - Posted: 07.15.2016

By Clare Wilson One day, you might be seeing in blue for 24 hours before you have an operation ­– to prevent organ damage. A study in mice suggests that exposure to blue light reduces a form of organ damage that is common during surgery. Reperfusion injury can happen when blood vessels are temporarily tied off during surgery, or when blocked arteries are surgically widened after a heart attack or stroke. Some damage is caused by a lack of oxygen, and further harm results when oxygen levels rebound, causing cells to become overactive, and triggering an attack by the immune system. But blue light seems to reduce this, in mice at least. Matthew Rosengart of the University of Pittsburgh, Pennsylvania, and his team have found that when mice are exposed to blue light for 24 hours before the blood supply to their liver or kidney is temporarily tied off, there is less reperfusion injury than if the mice are exposed to other types of light. “That’s pretty remarkable,” says Jack Pickard, a reperfusion researcher at University College London. Further tests showed that blue light seems to dampen down the sympathetic nervous system, which is involved in mammal stress responses. In turn, this reduced the activity of immune cells called neutrophils, which are involved in inflicting the damage of a reperfusion injury. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 22145 - Posted: 04.26.2016

By Lisa L. Lewis On Tuesday, U.S. News and World Report released its annual public high-school rankings, with the School for the Talented and Gifted in Dallas earning the top spot for the fifth year in a row. The rankings are based on a wealth of data, including graduation rates and student performance on state proficiency tests and advanced exams, as well as other relevant factors—like the percentage of economically disadvantaged students the schools serve. But there’s one key metric that isn’t tracked despite having a proven impact on academic performance: school start times. First-period classes at the School for the Talented and Gifted start at 9:15 a.m. That’s unusually late compared to other schools but is in keeping with the best practices now recommended by public health experts. Teens require more sleep than adults and are hardwired to want to sleep in. Eight hours a night may be the goal for adults, but teens need between 8.5–9.5 hours, according to the American Academy of Pediatrics. Unfortunately, few teens meet that minimum: Studies show that two out of three high school students get less than eight hours of sleep, with high school seniors averaging less than seven hours. Sure, kids could go to bed earlier. But their bodies are set against them: Puberty makes it hard for them to fall asleep before 11 p.m. When combined with too-early start times, the result is sleep deprivation.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory, Learning, and Development
Link ID: 22133 - Posted: 04.23.2016

By Victoria Sayo Turner Seasonal affective disorder was categorized under major depression to signify depression with a yearly recurrence, a condition far more debilitating than your average “winter blues.” Credit: ©iStock Around March, some of us take a kick at the snow mounded on the curb and wonder if spring is finally going to drop by. The sun sets before we go home, and the cold coops us up except for runs to the grocery store. All of this amounts to something known informally as the winter blues, because those wintry days and dead trees can put us in a glum mood. But in the 1980s, research at the National Institutes of Mental Health led to recognition of a form of depression known as seasonal affective disorder (shortened, of course, to SAD). Seasonal affective disorder was categorized under major depression to signify depression with a yearly recurrence, a condition far more debilitating than your average “winter blues.” Mention of SAD in research and books peaked in the 1990s, and today SAD is considered a diagnosable (and insurable) disorder. Treatment ranges from psychotherapy to antidepressants to light therapy — large boxes filled with lightbulbs that look like tanning beds for your face. However, a recent study questions the existence of seasonal depression entirely. Each year, the Centers for Disease Control conducts a large cross-sectional study of the US population. A group of researchers realized they could use the CDC results independently to investigate how much depression changes by season. The 2006 version of the CDC study included a set of questions typically used to screen for depression. By analyzing the answers gathered from 34,000 adults over the course of the year, the researchers might detect flareups of seasonal affective disorder. They might see wintertime surges in depression. “To be honest, we initially did not question the [SAD] diagnosis,” writes investigator Dr. Steven LoBello, the goal being “to determine the actual extent to which depression changes with the seasons.” © 2016 Scientific American

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 21994 - Posted: 03.16.2016

By HEATHER MURPHY Good morning. Or confusing morning, really. Come Daylight Saving Time each year, people often complain about how thrown off they feel by the shift of an hour. I thought they were just whiny. That is, until my dinosaur got jet lag and refused to glow. Since that’s not an everyday occurrence, let me explain the dinosaur first, and then I’ll get to how my dinosaur’s problems may be connected to your own struggles to function over the next few days. (Hint: It’s not only the loss of sleep that causes problems.) Created by a company called BioPop, my Dino Pet contains lots of itty bitty dinoflagellates. Dinoflagellates, if you are having trouble summoning a sixth-grade biology lesson, are usually ocean-dwelling, single-celled organisms also known as marine plankton. People typically encounter them when they clean the inside of their aquarium (this form is often referred “brown slime algae”) or if they happen to be kayaking through a bay filled with lots of bioluminescent ones. The ones that live in my plastic dinosaur (a Christmas gift) are the latter kind. Shake them just a bit and the transparent creatures become a glow-in-the-dark snow globe. Except that a week after I set my dinosaur up, it still refused to put on its shimmer show. I tried everything. I moved it from darker to lighter spots. I played it music and whispered encouraging words. But when I turned off the lights, my little dino remained depressingly dark. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 21981 - Posted: 03.14.2016

By Michelle Roberts Health editor, Exposure to short flashes of light at night could help sleeping travellers adjust to new time zones and avoid jet lag, according to US scientists. The light beams travel through the eyelids and this tells the brain to re-set the body's inner biological clock, the Stanford researchers believe. They tested the method in 39 volunteers and found it shifted a person's body clock by about two hours. An hour of the flashlight therapy was enough to achieve this effect. People's bodies synchronise to the 24-hour pattern of daytime and night they are used to. And when they travel across time zones to a new light-dark schedule, they need to realign. While most people can easily manage a long-haul flight across one or two time zones, crossing several time zones messes with the body clock. Jet lag can leave travellers tired, irritable and disorientated for days. As a remedy, some people take melatonin tablets, which mimic a hormone released in the evening. Some try phototherapy - light boxes that simulate daylight. But Dr Jamie Zeitzer and colleagues at Stanford University School of Medicine believe sleeping in front of a strobe light could work better. They asked volunteers to go to bed and wake up at the same times every day for about two weeks. Next, they were asked to sleep in the lab, where some were exposed to continuous light and others a strobe light (two-millisecond flashes of light, similar to a camera flash, 10 seconds apart) for an hour. The flashing-light group reported a nearly two-hour delay in the onset of sleepiness the following night. In comparison, the delay in sleepiness was 36 minutes for the continuous-light group. Dr Zeitzer calls his therapy "biological hacking". Cells in the back of the eye that detect the light send messages to a part of the brain that sets the body clock. The light fools the brain into thinking the day is longer than it really is, which shifts the inner clock. © 2016 BBC.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 21881 - Posted: 02.10.2016

Carl Zimmer Throughout the day, a clock ticks inside our bodies. It rouses us in the morning and makes us sleepy at night. It raises and lowers our body temperature and at the right times, and regulates the production of insulin and other hormones. From Our Advertisers The body’s circadian clock even influences our thoughts and feelings. Psychologists have measured some of its effects on the brain by having people take cognitive tests at different times of day. As it turns out, late morning turns out to be the best time to try doing tasks such as mental arithmetic that demand that we hold several pieces of information in mind at once. Later in the afternoon is the time to attempt simpler tasks, like searching for a particular letter in a page of gibberish. Another clue about the clock in our brains comes from people with conditions such as depression and bipolar disorder. People with these disorders often have trouble sleeping at night, or feel groggy during the day. Some people with dementia experience “sundowning,” becoming confused or aggressive at the end of the day. “Sleep and activity cycles are a very big part of psychiatric illnesses,” said Huda Akil, a neuroscientist at the University of Michigan. Yet neuroscientists have struggled to understand exactly how the circadian clock affects our minds. After all, researchers can’t simply pop open a subject’s skull and monitor his brain cells over the course of each day. A few years ago, Dr. Akil and her colleagues came up with an idea for the next best thing. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 21733 - Posted: 12.29.2015

The month of your birth influences your risk of developing dementia. Although the effect is small compared to risk factors such as obesity, it may show how the first few months of life can affect cognitive health for decades to come. Demographers Gabriele Doblhammer and Thomas Fritze from the University of Rostock, Germany, studied data from the Allgemeine Ortskrankenkasse – Germany’s largest public health insurer – for nearly 150,000 people aged 65 and over. After adjusting for age, they found that those born in the three months from December to February had a 7 per cent lower risk of developing dementia than those born in June to August, with the risk for other months falling in between. There’s nothing astrological about the effect, however. Instead, birth month is a marker for environmental conditions such as weather and nutrition, says Gerard van den Berg, an economist at the University of Bristol, UK, who studies the effects of economic circumstances on health. Summer-born babies are younger when they face the respiratory infections of their first winter, for example. And in the past, babies born in spring and summer would have been in late gestation when the supply of fresh fruit and vegetables from the autumn harvest would have largely run out. Pollution from wood fires or coal heating might also have played a role. There’s evidence from other studies that such factors can have lifelong effects on metabolism and the immune system, increasing the risk of conditions such as diabetes, obesity and high blood pressure. Doblhammer and Fritze’s results show this is true for dementia too. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory, Learning, and Development
Link ID: 21498 - Posted: 10.10.2015

By JOAN RAYMOND Rita Gunther McGrath, a Columbia Business School professor, is one of those business travelers who do not care about delays, cancellations or navigating a new location. What does concern her is the seeming inability to conquer jet lag, and the accompanying symptoms that leave her groggy, unfocused and feeling, she says, “like a dishrag.” “Jet lag has always been an issue for me,” says Ms. McGrath, who has been a business traveler for more than two decades and has dealt with itineraries that take her from New York to New Zealand to Helsinki to Hong Kong all within a matter of days. She has scoured the Internet for “jet lag cures,” and has tried preventing or dealing with the misery by avoiding alcohol, limiting light exposure or blasting her body with sunlight and “doing just about anything and everything that experts tell you to do,” Ms. McGrath said. “Jet lag is not conducive to the corporate environment,” she said. “There has to be some kind of help that actually works for those of us that travel a lot, but I sure can’t find it.” Although science is closer to understanding the basic biological mechanisms that make many travelers feel so miserable when crossing time zones, research has revealed that, at least for now, there is no one-size fits-all recommendation for preventing or dealing with the angst of jet lag. Recommendations to beat jet lag include adjusting sleep schedules, short-term use of medications to sleep or stay awake, melatonin supplements and light exposure timing, among others, said Col. Ian Wedmore, an emergency medicine specialist for the Army. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 21333 - Posted: 08.25.2015

Tina Hesman Saey The Earth has rhythm. Every 24 hours, the planet pirouettes on its axis, bathing its surface alternately in sunlight and darkness. Organisms from algae to people have evolved to keep time with the planet’s light/dark beat. They do so using the world’s most important timekeepers: daily, or circadian, clocks that allow organisms to schedule their days so as not to be caught off guard by sunrise and sunset. A master clock in the human brain appears to synchronize sleep and wake with light. But there are more. Circadian clocks tick in nearly every cell in the body. “There’s a clock in the liver. There’s a clock in the adipose [fat] tissue. There’s a clock in the spleen,” says Barbara Helm, a chronobiologist at the University of Glasgow in Scotland. Those clocks set sleep patterns and meal times. They govern the flow of hormones and regulate the body’s response to sugar and many other important biological processes (SN: 4/10/10, p. 22). Having timekeepers offers such an evolutionary advantage that species have developed them again and again throughout history, many scientists say. But as common and important as circadian clocks have become, exactly why such timepieces arose in the first place has been a deep and abiding mystery. Many scientists favor the view that multiple organisms independently evolved their own circadian clocks, each reinventing its own wheel. Creatures probably did this to protect their fragile DNA from the sun’s damaging ultraviolet rays. But a small group of researchers think otherwise. They say there had to be one mother clock from which all others came. That clock evolved to shield the cell from oxygen damage or perhaps provide other, unknown advantages. © Society for Science & the Public 2000 - 2015

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 21171 - Posted: 07.15.2015

by Colin Barras Bacteria aren't renowned for their punctuality – but perhaps one day they will be. A working circadian clock has been inserted in E. coli that allows the microbes to keep to a 24-hour schedule. The tiny timekeepers could eventually be used in biological computers or for combating the effects of jet lag. Many plants and animals use circadian clocks to regulate their daily activities – but bacterial circadian rhythms are much less well understood. The best studied belongs to photosynthetic cyanobacteria: other common microbes, like E. coli, don't carry clocks at all, says Pamela Silver of Harvard Medical School. The cyanobacterial clock is based around the kaiABC gene cluster and ATP – the molecular fuel that nearly all living cells rely on. During the day, while the cyanobacteria are active, the KaiA protein encourages the KaiC protein to bind to phosphate groups from ATP. At night, the KaiB protein kicks into action, disrupting the activity of KaiA and encouraging KaiC to hand back the phosphate. Silver, her former student Anna Chen and other colleagues have transplanted this kaiABC clock wholesale into E. coli – the first time such a sophisticated clock has been slotted into a new microbe. But would the bacteria use their new clocks to keep time? "That's the cleverest part – and it's down to Anna's genius," says Silver. Chen suggested hooking up the kaiABC clock to a green fluorescent protein so that the phosphorylated KaiC protein would make the E. coli glow. Sure enough, the E. coli became gradually more fluorescent and then returned to a non-fluorescent state over a 24-hour period, proving that the kaiABC clock kept ticking even after it was transplanted. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 21055 - Posted: 06.16.2015

Rob Stein The seasons appear to influence when certain genes are active, with those associated with inflammation being more active in the winter, according to new research released Tuesday. A study involving more than 16,000 people found that the activity of about 4,000 of those genes appears to be affected by the season, researchers reported in the journal Nature Communications. The findings could help explain why certain diseases are more likely than others to strike for the first time during certain seasons, the researchers say. "Certain chronic diseases are very seasonal — like seasonal affective disorder or cardiovascular disease or Type 1 diabetes or multiple sclerosis or rheumatoid arthritis," says John Todd, a geneticist at the University of Cambridge who led the research. "But people have been wondering for decades what the explanation for that is." Todd and his colleagues decided to try to find out. They analyzed the genes in cells from more than 16,000 people in five countries, including the United States and European countries in the Northern Hemisphere, and Australia in the Southern Hemisphere. And they spotted the same trend — in both hemispheres, and among men as well as women. "It's one of those observations where ... the first time you see it, you go, 'Wow, somebody must have seen this before,' " Todd says. Not all young girls avoid dirt. Hannah Rose Akerley, 7, plays in a gigantic lake of mud at the annual Mud Day event in Westland, Mich., last July. © 2015 NPR

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20922 - Posted: 05.13.2015

By Lena H. Sun Most babies in the United States are born on a weekday, with the highest percentages delivered between 8 a.m. to 9 a.m., and from noon to 1 p.m., according to a report published Friday by the National Center for Health Statistics. That won't come as too much of a surprise to many pregnant women who had cesarean deliveries. Most births in the United States take place in hospitals. And as C-sections and induced labor have increased during the past few decades, more deliveries take place during the day, to maximize coordination and care with doctors and hospital staff. But what happens if the baby isn't born in the hospital, but in the home, where most out-of-hospital births occur? (Less than 2 percent of all U.S. births take place outside the hospital.) Those births were most likely to take place in the wee morning hours between 1 a.m. and 4:59 a.m., the report found. The reason: mother nature. "Where nature is taking its course, infants are more likely to be born when it's completely dark out," said T.J. Mathews, a demographer with the National Center for Health Statistics, part of the U.S. Centers for Disease Control and Prevention. Researchers think evolution may have something to do with making the middle of the night an optimal time for delivery. Say you were pregnant and part of a nomadic tribe. Having your baby in the middle of the day could mean the rest of the tribe leaves you behind as they move from place to place. "You probably bled to death," said Aaron Caughey, chairman of the Department of Obstetrics and Gynecology at Oregon Health & Science University's School of Medicine.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 20904 - Posted: 05.09.2015

By Chris Cesare The beautiful color of a sunset might be more than just a pretty picture. It could be a signal to our bodies that it’s time to reset our internal clock, the biological ticktock that governs everything from sleep patterns to digestion. That’s the implication of a new study in mice that shows these small rodents use light’s changing color to set their own clocks, a finding that researchers expect will hold for humans, too. “I think this work opens up how we're just starting to scratch the surface and look at the environmental adaptations of clocks,” says Carrie Partch, a biochemist at the University of California, Santa Cruz, who was not involved in the new study. Scientists have long known about the role light plays in governing circadian rhythms, which synchronize life’s ebb and flow with the 24-hour day. But they weren’t sure how different properties of light, such as color and brightness, contributed to winding up that clock. “As a sort of common sense notion people have assumed that the clock somehow measures the amount of light in the outside world,” says Tim Brown, a neuroscientist at the University of Manchester in the United Kingdom and an author of the new study. “Our idea was that it might be doing something more sophisticated than that.” To find out, Brown and his colleagues targeted an area in the brain called the suprachiasmatic nucleus, or SCN, a region common to all vertebrates. It’s where the body keeps time using chemical and electrical rhythms that last, on average, 24 hours. The team wanted to know if color signals sent from the eyes reached the SCN and whether that information affected the timing of the clock. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 7: Vision: From Eye to Brain
Link ID: 20815 - Posted: 04.18.2015

By James Gallagher Health editor, Our internal body clock has such a dramatic impact on sporting ability that it could alter the chances of Olympic gold, say researchers. The team at the University of Birmingham showed performance times varied by 26% throughout the day. Early risers reached their athletic peak around lunchtime, while night owls were best in the evening. The researchers say it could even explain why Spanish teams have more success in European football. The body clock controls everything - from alertness to the risk of a heart attack - in a daily rhythm. Some aspects of sporting ability were thought to peak in early afternoon but a study in the journal Current Biology suggests each competitor's sleeping habits have a powerful impact. They took 20 female hockey players and asked them to perform a series of 20m runs in shorter and shorter times. And they did it at six different times of day between 07:00 and 22:00. The results showed a peak performance in late afternoon, but then the scientists looked separately at early-type people, late-type people and those in the middle. This time the gap between the best and worst times was 26%, and a far more complicated picture emerged. Lead researcher Dr Roland Brandstaetter told the BBC News website: "Athletes and coaches would benefit greatly if they knew when optimal or suboptimal performance time was." He said a 1% difference in performance would be the difference between fourth place and a medal in many Olympic events. Body clocks can be adjusted. Jet lag is when you feel rough before adjusting to a new time. "So if you're an early type in a competition in the evening, then you're impaired, so you could adjust sleeping times to the competition," Dr Brandstaetter said. © 2015 BBC.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 20540 - Posted: 02.02.2015

ARE you spending enough time in the sun? As well as keeping our bones strong, vitamin D – the hormone our skin makes when exposed to ultraviolet rays – may also help regulate our body clocks. We all have a small group of "clock genes" which switch on and off during the day. As a result, the levels of the proteins they code for rise and fall over a 24-hour period. Enforced routines such as night shift work can play havoc with our health – increasing our risk of a stroke, for example. To find out whether a lack of vitamin D might be responsible, Sean-Patrick Scott and his colleagues at the Monterrey Institute of Technology and Higher Education in Mexico looked at the behaviour of two clock genes in human fat cells. When the cells were immersed in blood serum, they acted as they would in the body: the clock genes' activity oscillated over a 24-hour period. Dosing the cells with vitamin D instead produced the same effect. No such effect was seen in cells placed inside a nutrient broth. "Vitamin D synchronises the cells," says Scott. "Our results explain some of the benefits of sunlight," he says. "Vitamin D is one of the ways we might be able to maintain circadian rhythms in the body." Julia Pakpoor of the University of Oxford says clinical trials are needed to confirm the effect in people, but she adds, "We should all make sure we are vitamin D replete regardless." The work was presented at the World Stem Cell Summit in San Antonio, Texas, last month. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 20454 - Posted: 01.06.2015

By James Gallagher Health editor, BBC News website Higher rates of obesity and ill-health have been found in shift workers than the general population. Health Survey for England data showed they were in worse health despite often being young. The lead researcher told the BBC that the rise of zero-hours contracts may be increasing the numbers doing shift work and could raise "pretty serious problems" for the nation's health. Scientists said it was "fairly clear now" that shift work was unhealthy. The report, by the Health and Social Care Information Centre, showed 33% of men and 22% of women of working age were doing shift work. They defined shifts as employment outside 0700-1900. Rachel Craig, the research director for the Health Survey for England, told the BBC: "Overall, people who are doing shift work are not quite as healthy as their counterparts doing regular working hours." The data showed 30% of shift workers were obese, compared with 24% of men and 23% of women doing normal hours. Meanwhile, 40% of men and 45% of women on shifts had long-standing health conditions such as back-pain, diabetes or chronic obstructive pulmonary disease compared with 36% and 39% of the rest of the population. Younger people Shift working is most common in the 16-24 age group with nearly half of men and a third of women having this working pattern. The rates fell with age so that fewer than a third of men and a fifth of women were working shifts after the age of 55. Ms Craig said that, overall, young people should be in better health: "You'd expect less ill-health and fewer long-standing conditions that reflect lifestyle like obesity, so it makes it an even stronger relationship [between shifts and poor health]." BBC © 2014

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 20424 - Posted: 12.16.2014