Links for Keyword: Biological Rhythms

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 236

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

By James Gallagher Health editor, BBC News website Working antisocial hours can prematurely age the brain and dull intellectual ability, scientists warn. Their study, in the journal Occupational and Environmental Medicine, suggested a decade of shifts aged the brain by more than six years. There was some recovery after people stopped working antisocial shifts, but it took five years to return to normal. Experts say the findings could be important in dementia, as many patients have disrupted sleep. The body's internal clock is designed for us to be active in the day and asleep at night. The damaging effects on the body of working against the body clock, from breast cancer to obesity, are well known. Now a team at the University of Swansea and the University of Toulouse has shown an impact on the mind as well. Three thousand people in France performed tests of memory, speed of thought and wider cognitive ability. The brain naturally declines as we age, but the researchers said working antisocial shifts accelerated the process. Those with more than 10 years of shift work under their belts had the same results as someone six and a half years older. The good news is that when people in the study quit shift work, their brains did recover. Even if it took five years. Dr Philip Tucker, part of the research team in Swansea, told the BBC: "It was quite a substantial decline in brain function, it is likely that when people trying to undertake complex cognitive tasks then they might make more mistakes and slip-ups, maybe one in 100 makes a mistake with a very large consequence, but it's hard to say how big a difference it would make in day-to-day life." BBC © 2014

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 13: Memory, Learning, and Development
Link ID: 20281 - Posted: 11.05.2014

BY Bethany Brookshire We all need sleep, but attaining it can be delicate. Insomniacs can’t fall or stay asleep. Travelers suffer from jetlag. Anxiety keeps people up at night. Or maybe it’s just that jackhammer running across the street keeping your eyes open. Some people turn to earplugs, dark curtains or alcohol to soothe them to sleep. But others go to the supplement aisle and pick up melatonin. The hormone melatonin is secreted from our brains at night and helps regulate sleep. But this chemical is not restricted to humans, or even to mammals. The roots of melatonin’s role in our nightly slumbers go back much further in evolutionary history. A new paper focuses in on the role of melatonin in tiny marine creatures called zooplankton. It turns out that these animals use melatonin just as much as we do, suggesting that the origins of sleeplike behavior may lie under the sea. “For every system and feature that makes a human or other animal today, you can ask the question: Where did it start? How did it begin? What was its first role and function, and how did it become more complex?” says study coauthor Detlev Arendt, a zoologist at the University of Heidelberg in Germany. Arendt’s laboratory has been studying the answers to these questions in the marine ragworm Platynereis dumerilii. This unassuming, centipede-like, ocean-dwelling worm produces larvae that float through the open water as zooplankton. These small larvae propel themselves up and down in the water column with movements of their cilia, slender, hair-like appendages that protrude out from the organisms. © Society for Science & the Public 2000 - 2014.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 20180 - Posted: 10.08.2014

by Sarah Zielinski Small, silver fish called Mexican tetra (Astyanax mexicanus) live in some Texas and Mexican rivers. Some members of the species — eyeless and blind — can be found in nearby freshwater caves. Sometimes the sighted fish wash into a cave, but they don’t do nearly as well as their blind brethren. Any surface dweller unlucky enough to end up in the dark would have some disadvantages: It would have to adapt to the loss of light and forage for unfamiliar foods, which may be not as abundant as those found in their home waters. But the fish’s biggest disadvantage may be its metabolism. Blind cavefish have lost their circadian rhythms and have developed more efficient metabolisms than the fish that live in the light, researchers report September 24 in PLOS ONE. To measure tetras’ metabolism, Damian Moran and colleagues at Lund University in Sweden placed fish in a contraption that let the fish swim in place while the researchers tracked their oxygen consumption, a measure of their metabolism. Surface and cave fish were placed in the tank under constant darkness or 12-hour light-and-dark cycles for 7 or 8 days. Then the researchers compared how the fish did under the different light regimes. All the fish took a few days to acclimate to the laboratory conditions. In the light-and-dark conditions, surface fish showed a clear circadian pattern to their oxygen consumption. These fish ramped up their metabolism by about 20 percent during the day. That increase in metabolism would let them have more energy for their hunts and feeding, which take place in the light. © Society for Science & the Public 2000 - 2014

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 20134 - Posted: 09.30.2014

By Meeri Kim The pervasive glow of electronic devices may be an impediment to a good night’s sleep. That’s particularly noticeable now, when families are adjusting to early wake-up times for school. Teenagers can find it especially hard to get started in the morning. For nocturnal animals, it spurs activity. For daytime species such as humans, melatonin signals that it’s time to sleep. As lamps switch off in teens’ bedrooms across America, the lights from their computer screens, smartphones and tablets often stay on throughout the night. These devices emit light of all colors, but it’s the blues in particular that pose a danger to sleep. Blue light is especially good at preventing the release of melatonin, a hormone associated with nighttime. Ordinarily, the pineal gland, a pea-size organ in the brain, begins to release melatonin a couple of hours before your regular bedtime. The hormone is no sleeping pill, but it does reduce alertness and make sleep more inviting. However, light — particularly of the blue variety — can keep the pineal gland from releasing melatonin, thus warding off sleepiness. You don’t have to be staring directly at a television or computer screen: If enough blue light hits the eye, the gland can stop releasing melatonin. So easing into bed with a tablet or a laptop makes it harder to take a long snooze, especially for sleep-deprived teenagers who are more vulnerable to the effects of light than adults. During adolescence, the circadian rhythm shifts, and teens feel more awake later at night. Switching on a TV show or video game just before bedtime will push off sleepiness even later even if they have to be up by 6 a.m. to get to school on time.

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: 20021 - Posted: 09.02.2014

|By Mark Fischetti Parents, students and teachers often argue, with little evidence, about whether U.S. high schools begin too early in the morning. In the past three years, however, scientific studies have piled up, and they all lead to the same conclusion: a later start time improves learning. And the later the start, the better. Biological research shows that circadian rhythms shift during the teen years, pushing boys and girls to stay up later at night and sleep later into the morning. The phase shift, driven by a change in melatonin in the brain, begins around age 13, gets stronger by ages 15 and 16, and peaks at ages 17, 18 or 19. Does that affect learning? It does, according to Kyla Wahlstrom, director of the Center for Applied Research and Educational Improvement at the University of Minnesota. She published a large study in February that tracked more than 9,000 students in eight public high schools in Minnesota, Colorado and Wyoming. After one semester, when school began at 8:35 a.m. or later, grades earned in math, English, science and social studies typically rose a quarter step—for example, up halfway from B to B+. Two journal articles that Wahlstrom has reviewed but have not yet been published reach similar conclusions. So did a controlled experiment completed by the U.S. Air Force Academy, which required different sets of cadets to begin at different times during their freshman year. A 2012 study of North Carolina school districts that varied school times because of transportation problems showed that later start times correlated with higher scores in math and reading. Still other studies indicate that delaying start times raises attendance, lowers depression rates and reduces car crashes among teens, all because they are getting more of the extra sleep they need. © 2014 Scientific American

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: 19989 - Posted: 08.25.2014

By James Gallagher Health editor, BBC News website Even low levels of light in bedrooms may stop breast cancer drugs from working, US researchers have warned. Animal tests showed light, equivalent to that from street lamps, could lead to tumours becoming resistant to the widely used drug Tamoxifen. The study, published in the journal Cancer Research, showed the light affected sleep hormones, which in turn altered cancer cell function. UK experts said it was an intriguing finding, but not proven in people. Tamoxifen has transformed the treatment of breast cancer by extending lives and increasing survival times. It stops the female hormone oestrogen fuelling the growth of tumours although the cancerous cells may eventually become resistant to the drug. Light Researchers at the Tulane University School of Medicine investigated the role of the body clock in Tamoxifen resistance. They focused their research on the sleep-promoting hormone melatonin, which normally begins to rise in the evening and continues through the night, before falling away as dawn approaches. However, light in the evening - such as from a smartphone, tablet or artificial lights - can lower melatonin levels. Rats, with human breast cancer and treated with Tamoxifen, were left to sleep in a completely dark cage or one that had dim light. The scientists showed that in dim light, melatonin levels were lower, the tumours were bigger and were resistant to Tamoxifen. A second set of tests showed that giving those mice melatonin supplements kept Tamoxifen working and resulted in smaller tumours. BBC © 2014

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 19881 - Posted: 07.26.2014

By Kelly Clancy In one important way, the recipient of a heart transplant ignores its new organ: Its nervous system usually doesn’t rewire to communicate with it. The 40,000 neurons controlling a heart operate so perfectly, and are so self-contained, that a heart can be cut out of one body, placed into another, and continue to function perfectly, even in the absence of external control, for a decade or more. This seems necessary: The parts of our nervous system managing our most essential functions behave like a Swiss watch, precisely timed and impervious to perturbations. Chaotic behavior has been throttled out. Or has it? Two simple pendulums that swing with perfect regularity can, when yoked together, move in a chaotic trajectory. Given that the billions of neurons in our brain are each like a pendulum, oscillating back and forth between resting and firing, and connected to 10,000 other neurons, isn’t chaos in our nervous system unavoidable? The prospect is terrifying to imagine. Chaos is extremely sensitive to initial conditions—just think of the butterfly effect. What if the wrong perturbation plunged us into irrevocable madness? Among many scientists, too, there is a great deal of resistance to the idea that chaos is at work in biological systems. Many intentionally preclude it from their models. It subverts computationalism, which is the idea that the brain is nothing more than a complicated, but fundamentally rule-based, computer. Chaos seems unqualified as a mechanism of biological information processing, as it allows noise to propagate without bounds, corrupting information transmission and storage. © 2014 Nautilus,

Related chapters from BP7e: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 10: Biological Rhythms and Sleep
Link ID: 19859 - Posted: 07.21.2014

by Azeen Ghorayshi Food could be a new weapon in shaking off the effects of jet lag after research in mice showed that the insulin released as a result of eating can be a key factor in restoring a disrupted body clock. Miho Sato and her colleagues at The Research Institute for Time Studies at Yamaguchi University in Japan did experiments in mice and tissue cultures to show, for the first time, that increases in insulin affect circadian rhythms. These daily rhythms affect alertness, sleep patterns, and mediate many other physiological processes. Your biological clock is regulated by two broad factors: first, the central rhythm is reset daily by light, as sensory input from the eyes is processed by a small part of the brain called the suprachiasmatic nucleus. The rise and fall of hormones linked to sleep, for example, match this rhythm. But circadian rhythms are also present in peripheral "clocks" in a wide range of cell types in the body. Some of these can be influenced by food. Sato demonstrated the role of insulin by shifting the peripheral body clock in the livers of mice by feeding them only at night. They then split the mice into two groups, supressed insulin levels in one group, and returned all the mice to daytime feeding. Four days later, the livers of the non-supressed mice had readjusted to a normal daily rhythm, as revealed by the daily rise and fall of liver-gene expression. The livers of the insulin-suppressed mice had still not returned to normal. © Copyright Reed Business Information Ltd.

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: 19830 - Posted: 07.15.2014

|By William Skaggs Jet lag is a pain. Besides the inconvenience and frustration of traveling more than a few time zones, jet lag likely causes billions of dollars in economic losses. The most effective treatment, according to much research, is structured exposure to light, although the drug melatonin may also sometimes be helpful at bedtime. Both approaches have been used for more than 20 years, and during that time no viable new interventions have appeared. Recently, however, research into the molecular biology of circadian rhythms has raised the prospect of developing new drugs that might produce better results. Jet lag occurs when the “biological clock” in the brain becomes misaligned with the local rhythm of daily activity. The ultimate goal of circadian medicine is a treatment that instantly resets the brain's clock. Failing that, it would be helpful to have treatments that speed the rate of adjustment. Four recent discoveries suggest new possibilities. The first involves vasopressin, which is the main chemical signal used to synchronize cellular rhythms of activity in the brain area that is responsible for our biological clock. Blocking vasopressin makes it much easier to reset this clock. Potentially, a drug that interferes with vasopressin could work as a fast-acting treatment for jet lag. The second and third possibilities involve a pair of brain chemicals called salt-inducible kinase 1 (SIK1) and casein kinase 1ε (CK1ε), both of which limit the ability of light to reset the brain's clock. Drugs already exist that interfere with their action and greatly increase the effectiveness of light exposure. The existing drugs are not viable jet-lag treatments, because they are hard to administer and have unpleasant side effects, but researchers hope better drugs can be developed that work in a similar way. © 2014 Scientific American,

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 19826 - Posted: 07.14.2014

by Meghan Rosen Shaking off jet lag could be as easy as downloading an app. Researchers developed the iPhone app, called Entrain, using mathematical analyses of humans’ daily rhythms to calculate the quickest way to adjust to new time zones. Users plug in their destination and arrival time, and Entrain advises times of the day to soak up or stay out of the light. The schedules are surprisingly simple, says mathematical biologist Daniel Forger, of the University of Michigan in Ann Arbor. “They might say, ‘Hey you should keep the lights on in your room until midnight,’” he says. “Or ‘you should stay in darkness until 10 a.m.’” Scientists have previously created mathematical equations that describe how humans’ internal clocks respond to light, Forger says. He and a colleague used a computer program to solve the tricky problem of finding the best lighting schedules for more than 1,000 possible trips. To do so, the researchers asked a question: If a traveler wants to move their body’s clock from New York to London time, for instance, what lighting schedule gets them there fastest? The pair reports the results April 10 in PLOS Computational Biology. K. Serkh and D.B. Forger. Optimal schedules of light exposure for rapidly correcting circadian misalignment. PLOS Computational Biology. Vol.10, April 10, 2014, p. e1003525. Doi: 10.1371/journal.pcbi.1003523. © Society for Science & the Public 2000 - 2013.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 19472 - Posted: 04.12.2014

By JAN HOFFMAN COLUMBIA, Mo. – Jilly Dos Santos really did try to get to school on time. She set three successive alarms on her phone. Skipped breakfast. Hastily applied makeup while her fuming father drove. But last year she rarely made it into the frantic scrum at the doors of Rock Bridge High School here by the first bell, at 7:50 a.m. Then she heard that the school board was about to make the day start even earlier, at 7:20 a.m. “I thought, if that happens, I will die,” recalled Jilly, 17. “I will drop out of school!” That was when the sleep-deprived teenager turned into a sleep activist. She was determined to convince the board of a truth she knew in the core of her tired, lanky body: Teenagers are developmentally driven to be late to bed, late to rise. Could the board realign the first bell with that biological reality? The sputtering, nearly 20-year movement to start high schools later has recently gained momentum in communities like this one, as hundreds of schools in dozens of districts across the country have bowed to the accumulating research on the adolescent body clock. In just the last two years, high schools in Long Beach, Calif.; Stillwater, Okla.; Decatur, Ga.;, and Glens Falls, N.Y., have pushed back their first bells, joining early adopters in Connecticut, North Carolina, Kentucky and Minnesota. The Seattle school board will vote this month on whether to pursue the issue. The superintendent of Montgomery County, Md., supports the shift, and the school board for Fairfax County, Va., is working with consultants to develop options for starts after 8 a.m. © 2014 The New York Times Company

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: 19366 - Posted: 03.15.2014

by Kat Arney Feeling dopey? Refresh your "circadian eye" with a burst of orange light. Light is a powerful wake-up call, enhancing alertness and activity. Its effect is controlled by a group of photoreceptor cells in the eyeball that make the light-sensing pigment melanopsin. These cells, which work separately to the rods and cones needed for vision, are thought to help reset animals' body clocks - or circadian rhythms. Studies with people who are blind suggest this also happens in humans, although the evidence isn't conclusive. To find out how melanopsin wakes up the brain, Gilles Vandewalle at the University of Liege, Belgium, and his team gave 16 people a 10-minute blast of blue or orange light while they performed a memory test in an fMRI scanner. They were then blindfolded for 70 minutes, before being retested under a green light. People initially exposed to orange light had greater brain activity in several regions related to alertness and cognition when they were retested, compared with those pre-exposed to blue light. Light switch Vandewalle thinks that melanopsin is acting as a kind of switch, sending different signals to the brain depending on its state. Orange light, which has the longer wavelength, is known to make the pigment more light-sensitive, but blue light has the opposite effect. Green light lies somewhere in the middle. The findings suggest that pre-exposure to orange light pushes the balance towards the more light-sensitive form of melanopsin, enhancing the response in the brain. © Copyright Reed Business Information Ltd.

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: 19345 - Posted: 03.11.2014

By James Gallagher Health and science reporter, BBC News Doing the night shift throws the body "into chaos" and could cause long-term damage, warn researchers. Shift work has been linked to higher rates of type 2 diabetes, heart attacks and cancer. Now scientists at the Sleep Research Centre in Surrey have uncovered the disruption shift work causes at the deepest molecular level. Experts said the scale, speed and severity of damage caused by being awake at night was a surprise. The human body has its own natural rhythm or body clock tuned to sleep at night and be active during the day. It has profound effects on the body, altering everything from hormones and body temperature to athletic ability, mood and brain function. The study, published in Proceedings of the National Academy of Sciences, followed 22 people as their body was shifted from a normal pattern to that of a night-shift worker. Blood tests showed that normally 6% of genes - the instructions contained in DNA - were precisely timed to be more or less active at specific times of the day. Once the volunteers were working through the night, that genetic fine-tuning was lost. "Over 97% of rhythmic genes become out of sync with mistimed sleep and this really explains why we feel so bad during jet lag, or if we have to work irregular shifts," said Dr Simon Archer, one of the researchers at the University of Surrey. BBC © 2014

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 19156 - Posted: 01.21.2014

By C. CLAIBORNE RAY Q. Why do I wake up at exactly the same time every night, without any stimulus? It has happened all my life, and it doesn’t even matter what time I went to bed. A. What you are experiencing is probably a normal period of relative alertness that happens in the middle of the night, said Dr. Carl W. Bazil, director of the division of epilepsy and sleep at NewYork-Presbyterian/Columbia University Medical Center. “Most people realize that there is a natural drowsiness midday, usually around lunchtime,” Dr. Bazil said. “This is why many fortunate cultures developed the siesta.” But the reverse normally happens at night. The two interludes are both part of the body’s circadian rhythm, which he said is “controlled by an internal clock but of course influenced by lots of external things,” like caffeine, light, exercise and stress. Dr. Bazil said it might also help those who wake up midsleep to know that “before the advent of electrical lighting, it was normal for people to go to bed at sundown, sleep for about four hours and arise during that natural alertness for a few hours before returning for a ‘second sleep.’ ” © 2014 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: 19124 - Posted: 01.14.2014