Links for Keyword: Biological Rhythms

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By RANDOLPH E. SCHMID WASHINGTON — Reports of sleeping air traffic controllers highlight a long-known and often ignored hazard: Workers on night shifts can have trouble concentrating and even staying awake. "Government officials haven't recognized that people routinely fall asleep at night when they're doing shift work," said Dr. Charles Czeisler, chief of sleep medicine at Brigham and Women's Hospital in Boston. Czeisler said studies show that 30 percent to 50 percent of night-shift workers report falling asleep at least once a week while on the job. So the notion that this has happened only a few times among the thousands of controllers "is preposterous," he said in a telephone interview. In a sign of growing awareness of the problem, the Federal Aviation Administration said Saturday it was changing air traffic controllers' work schedules most likely to cause fatigue. The announcement comes after the agency disclosed another incident in which a controller fell asleep while on duty early Saturday morning at a busy Miami regional facility. According to a preliminary review, there was no impact to flight operations, the FAA said. Czeisler said the potential danger isn't limited to air traffic controllers, but can apply to truck and bus drivers, airline pilots and those in the maritime industry. Who else? Factory workers, police, firefighters, emergency workers, nurses and doctors, cooks, hotel employees, people in the media and others on night or changing shifts. Copyright 2011 The Associated Press.

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: 15231 - Posted: 04.18.2011

Having the lights on before bedtime could result in a worse night's sleep, according to a study to be published in the Journal of Endocrinology and Metabolism. The research shows that the body produces less of the sleep hormone melatonin when exposed to light. Sleep patterns have been linked to some types of cancer, blood pressure and diabetes. The US researchers also found lower melatonin levels in shift workers. Lifestyles may have moved on from a day/night rhythm, but it seems the human body has not. The pineal gland produces melatonin through the night and starts when darkness falls. Researchers have shown that switching on lights in the home switches off the hormone's production. In the study, 116 people spent five days in room where the amount of light and sleep was controlled. They were awake for 16 hours and asleep for eight hours each day. Initially the patients were exposed to 16 hours of room light during their waking hours. They were then moved onto eight hours of room light in the morning and eight hours of dim light in the evening. The researchers found that electrical light between dusk and bedtime strongly suppressed melatonin levels. With dim light, melatonin was produced for 90 minutes more a day. BBC © MMXI

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: 14880 - Posted: 01.17.2011

By Susan Milius SALT LAKE CITY — As summer heats up, the sight of blooming thistles may give male goldfinches a testosterone kick. Thistle flowers could signal to American goldfinches that the seeds the songbirds prize for baby food and parent food will soon be abundant, proposes Thomas Luloff of the University of Western Ontario in London, Canada. And in lab setups, male goldfinches housed among blooming Canadian thistles underwent physiological changes that indicate the birds got the “breed now” message from the combination of summery heat and thrilling thistles, Luloff reported January 6 at the annual meeting of the Society for Integrative and Comparative Biology. What particularly impressed George Bentley of the University of California, Berkeley was that the birds “don’t eat the flower — they eat the seeds,” he says. Yet the precursor to food still appeared to have an effect. Biologists still have much to learn about what tips off birds that it’s time to breed, says Bentley, who was not part of the research project. Yet, he says, the need to understand those cues is growing as climate change threatens to knock signals out of sync. Many birds lose what they don’t use during the winter, letting hormone concentrations dwindle and reproductive organs shrink. When the breeding season returns, both males and females typically have to recharge and regrow. Much of the earlier work on breeding signals has focused on the broad role of day length or temperature, yet birds can react to other cues too. Species differ in what cues or mixes of cues rev up their breeding biology again. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 8: Hormones and Sex
Link ID: 14862 - Posted: 01.13.2011

By RONI CARYN RABIN Antidepressants like Prozac and Paxil are widely used to treat depression, but a much less costly alternative called bright light therapy, in which a patient sits under an artificial light for a set period of time each day, is not. Light therapy is typically recommended for seasonal affective disorder, the “winter blues” brought on by shorter days and limited sun. Some psychiatrists prescribe it for this condition, often as a last resort when patients fail to respond to drugs. One reason light therapy hasn’t been used in more people with depression is that there aren’t many good clinical trials of the therapy in depressed patients without seasonal affective disorder. There isn’t much money to be made from the treatment — all it involves is a one-time purchase of a special lamp. The upside is that it has few, if any, side effects (though, doctors note, it should always be done in consultation with a physician). Now a new, carefully designed randomized controlled trial — of the kind considered the gold standard in medicine — suggests bright light therapy deserves a closer look. The study was small, involving only 89 patients ages 60 and older, but the results were remarkable. Compared with a placebo, light therapy improved mood just as well as conventional antidepressant medications, said Dr. Ritsaert Lieverse, the paper’s lead author and a psychiatrist at the VU University Medical Center in Amsterdam. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 10: Biological Rhythms and Sleep
Link ID: 14848 - Posted: 01.10.2011

by Nathan Collins Add this to your list of worries, high schoolers: daylight savings time might mess with your college admissions. For decades, scientists have debated whether spring and fall time changes affect everything from seasonal affective disorder to traffic accidents. The idea is that resetting clocks by "springing forward" and "falling back" can upset sleep patterns and with them the ability to concentrate. Now, it appears that these time changes might just muck up performance on the SAT, the U.S. college admissions exam, which is administered five times a year, including two dates that fall after daylight savings transitions. Using data from Indiana, where until recently individual counties could opt in or out of daylight savings, researchers found that scores in counties that changed their clocks were consistently 16.34 points—or 2%—lower than in counties that did not, they report online this month in the Journal of Neuroscience, Psychology, and Economics. That may not sound like a lot, but it may be enough to keep you out of Harvard. So choose your test dates carefully, kids. Springing forward could land you in your fall-back school. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 14: Attention and Consciousness
Link ID: 14702 - Posted: 11.23.2010

By Nicholette Zeliadt Our sleep patterns, eating habits, body temperature and hormone levels are driven by the rhythmic activity of body's circadian clock. Travel across time zones or shift work can knock those rhythms out of whack, possibly leading to sleep problems, bipolar disorder, metabolic syndrome and even cancer. The lack of convenient and reliable methods to monitor the internal clock's activity has severely limited the study of circadian-related disease, but now, scientists report that they can easily track the circadian rhythms by analyzing a person's plucked hairs. The finding could one day help doctors diagnose and treat patients suffering from circadian dysfunction. The body's master clock, located in the brain region called the hypothalamus, is set by light, which activates clock genes that are responsible for keeping this timekeeper ticking correctly. Within the past decade, scientists have discovered that organs outside the brain (such as the skin, liver and pancreas) also keep track of time with 24-hour fluctuations in clock gene expression. Previous studies have attempted to monitor molecular timekeeping in blood cells or in cells lining the mouth, but these approaches are technically challenging. In an attempt to develop a simpler, noninvasive method to clock circadian rhythms, researchers led by Makoto Akashi of the Research Institute for Time Studies at Yamaguchi University in Japan obtained hairs plucked from volunteers' heads or chins and analyzed clock gene expression in hair follicle cells. They report online this week in the Proceedings of the National Academy of Sciences that the patterns of circadian gene expression in the hair follicle cells accurately reflected the subjects' behavioral rhythms, "demonstrating that this strategy is appropriate for evaluating the human peripheral circadian clock." © 2010 Scientific American

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 14391 - Posted: 08.24.2010

By Katherine Harmon Having a mixed up body clock has been linked to a vast array of ailments, including obesity and bipolar disorder. And researchers are still trying to understand just how these cyclical signals influence aspects of our cellular and organ system activity. Now, a study published online August 3 in Cell Metabolism shows that in mice, a disrupted circadian rhythm spurs an increase in triglycerides—heightened levels of which have been linked to heart disease and metabolic syndrome in humans. To find this link, researchers compared normal lab mice to those bred to have dysfunctional sleep-wake cycles. As nocturnal animals, the control mice had the lowest levels of triglycerides at night, when they were most active, and higher levels during the daytime rest period. The mice with out-of-whack cycles kept confused hours, fed longer and were less active overall. These mutant mice also had far less fluctuation in their triglyceride levels. "We show that the normal up and down [of triglycerides] is lost in clock mutants," M. Mahmood Hussain, of the Department of Cell Biology and Pediatrics at the State University of New York Downstate Medical Center in Brooklyn and coauthor of the paper, said in a prepared statement. The mutant mice had "high triglycerides all the time," he noted. © 2010 Scientific American,

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: 14322 - Posted: 08.05.2010

by Sujata Gupta WHAT happens when you take blind mice and see how they run? It turns out they can identify objects using receptors in the eye that were previously thought to have no role in forming images. Since humans possess the same receptors, the finding could point the way to giving blind people some ability to see. Mice, and humans, have three types of light-detecting receptor in the eye. Rods and cones detect light, darkness, shape and colour, and make normal sight possible. Receptors of the third type, the melanopsin-containing ganglion cells (MCGCs), were until now thought only to respond to light over longer periods of time, to help moderate patterns of sleep and wakefulness. To investigate their role in vision, Samer Hattar of the Krieger School of Arts and Sciences at Johns Hopkins University in Baltimore, Maryland, and colleagues engineered mice to lack rods and cones. When these mice were placed in a maze, they were able to identify a lever with a visible pattern on it which allowed them to escape. Mice that lacked rods, cones and MCGCs could not find the lever. In another task, the team found that the MCGC mice could follow the movement of a rotating drum (Neuron, DOI: 10.1016/j.neuron.2010.05.023). This suggests MCGCs can form "low-acuity yet measurable images", Hatter says. Tom Cronin at the University of Maryland notes that the mice in the experiment behave like people with "blindsight", who can navigate round objects without consciously perceiving them. "It's mind-boggling but I suspect that the mice are doing something like that," he says. © 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: 14284 - Posted: 07.24.2010

By Lindsey Tanner Want happier, more alert teenagers? Let them sleep in a little. A new study reveals that delaying the school day by 30 minutes results in teens who are less sleepy and depressed. Scientists say that teens tend to be in their deepest sleep around dawn, when they typically need to arise for school. Interrupting that sleep can leave them groggy. Giving teens 30 extra minutes to start their school day leads to more alertness in class, better moods, less tardiness, and even healthier breakfasts, a small study found. "The results were stunning. There's no other word to use," said Patricia Moss, academic dean at the Rhode Island boarding school where the study was done. "We didn't think we'd get that much bang for the buck." The results appear in July's Archives of Pediatrics & Adolescent Medicine. The results mirror those at a few schools that have delayed starting times more than half an hour. Researchers say there's a reason why even 30 minutes can make a big difference. Teens tend to be in their deepest sleep around dawn -- when they typically need to arise for school. Interrupting that sleep can leave them groggy, especially since they also tend to have trouble falling asleep before 11 p.m. © 2010 Associated Press/AP Online

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: 14240 - Posted: 07.08.2010

by Andy Coghlan A FAULTY internal clock in the cells in the pancreas that produce insulin could be behind type 2 diabetes - a condition in which the body is unable to produce or use insulin properly. The finding suggests that disruption of natural night and day cycles through artificial lighting may be a factor in the emergence of type 2 diabetes in adults. It also fits with studies showing that shift workers are unusually prone to the condition. Insulin is produced by beta cells to control glucose levels in the blood. Joseph Bass of Northwestern University in Evanston, Illinois, and colleagues grew mouse beta cells in the lab to monitor insulin secretion. They found that beta cells lacking circadian "clock" genes produced 50 per cent less insulin, showing that these genes are essential for normal insulin production (Nature, DOI: 10.1038/nature09253). Likewise, live mice with disrupted clock genes rapidly developed type 2 diabetes. The next step, says Bass, is to identify the "switch" in beta cells that responds to the clock, and use it to develop a treatment. "The key thing the researchers have shown is that disruption of this internal clock causes a defect in insulin secretion," says Noel Morgan of the Peninsula Medical School in Exeter, UK, who studies type 1 diabetes, in which the body's own immune system destroys its beta cells. © 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: 14199 - Posted: 06.24.2010

By ANDREW POLLACK It seemed like the offer of a lifetime — earn $2,500 by flying to France aboard a private luxury jet. Even if it wins Food and Drug Administration approval, Nuvigil would have to compete with cheap jet-lag treatments like coffee. But as the fine print made clear, there would be no Eiffel Tower or chateaux, no foie gras or Bordeaux. Travelers were confined to a laboratory in either Toulouse or Rouffach with electrodes attached to their heads, testing whether a drug could keep their jet-lagged bodies awake. That drug, Nuvigil from Cephalon, could become the first medicine specifically approved by the Food and Drug Administration to combat jet lag. A jet-lag antidote might seem to be the latest lifestyle drug, a further step in the “medicalization” of something that is not an illness. But sleep specialists, who call the affliction “jet lag disorder,” say that while not exactly a disease, it is a condition that can be dangerous — as when someone tries to drive a car right after arriving in a distant time zone. For Cephalon, a company in Frazer, Pa., whose business tactics have attracted federal attention, the approval for jet lag is part of a plan to extend patent protection for its core franchise in stay-awake drugs. Copyright 2010 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: 13643 - Posted: 06.24.2010

By David Ropeik It’s that time of year, when crocuses bloom, the lawn starts to need mowing, and most Americans lose an hour’s sleep setting their clocks ahead. (Remember? Spring forward, fall back.) So here are answers to your questions about the time switch — and about sleep. Most Americans move their clocks ahead for daylight-saving time in the wee hours of the second Sunday in March. The day of the big switch used to be the first Sunday of April, but Congress put a new rule into effect last year as an energy-saving measure. What's the rationale behind the switchover? As the year progresses toward the June solstice, the Northern Hemisphere gets longer periods of sunlight. Timekeepers came up with daylight-saving time — or summer time, as it’s known in other parts of the world — to shift some of that extra sun time from the early morning (when timekeepers need their shut-eye) to the evening (when they play softball). The idea is that having the extra evening sunlight will cut down on the demand for lighting, and hence cut down on electricity consumption — and that few people will miss having it a little darker at, say, 6 o'clock in the morning. At least that's how the theory goes. © 2008 Microsoft

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 11393 - Posted: 06.24.2010

Inside the bodies of animals from fruit flies to humans, internal clocks are constantly ticking, making sure activity levels and a host of physiological functions rise and fall in a 24-hour cycle. Inside cells, many of the proteins that keep the internal clocks ticking on time have their own cycles, accumulating when they are needed, then vanishing when their work is done for the day. A newly identified gene mutation in mice has now revealed how these molecular oscillations are kept on track. Howard Hughes Medical Institute investigator Joseph Takahashi and his colleagues discovered the gene's role in regulating circadian rhythms, which they reported in the journal Cell, published online as an immediate early publication on April 26 and published in print on June 1, 2007. Joint lead authors in Takahashi's Northwestern University laboratory were Sandra Siepka and Seung-Hee Yoo, and another co-author, Choogon Lee, is from Florida State University. The team named the mutated gene Overtime because it knocks the mouse's circadian clock out of whack, lengthening its sleep-wake cycle to 26 hours. Circadian rhythms, the activity patterns that occur on a 24-hour cycle, are important biological regulators in virtually every living creature. In humans and other animals, the brain's internal circadian clock regulates sleep and wake cycles, as well as body temperature, blood pressure, and the release of various endocrine hormones. © 2007 Howard Hughes Medical Institute

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 10227 - Posted: 06.24.2010

Researchers from Brigham and Women’s Hospital (BWH) in Boston and Jefferson Medical College have found that the body’s natural biological clock is more sensitive to shorter wavelength blue light than it is to the longer wavelength green light, which is needed to see. The discovery proves what scientists have suspected over the last decade: a second, non-visual photoreceptor system drives the body’s internal clock, which sets sleep patterns and other physiological and behavioral functions. “This discovery will have an immediate impact on the therapeutic use of light for treating winter depression and circadian disorders,” says George Brainard, Ph.D., professor of neurology at Jefferson Medical College of Thomas Jefferson University in Philadelphia. “Some makers of light therapy equipment are developing prototypes with enhanced blue light stimuli.” ©2003 Thomas Jefferson University Hospital

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 4245 - Posted: 06.24.2010

Discovery that clocks in organs use different genes could impact postgenomic research and circadian medicine BOSTON, MA –The daily rhythms of the body—once thought to be strictly governed by a master clock lodged in the brain—appear to be driven to a remarkable degree by tiny timepieces pocketed in organs all over the body. What‘s more, these peripheral timepieces appear to be strikingly idiosyncratic in appearance—more like Swatch watches than classic Timexes. Clocks located in the liver and heart appear to use very different sets of genes to perform essentially the same functions, researchers at Harvard Medical School and the Harvard School of Public Health report in the April 21 Nature online. The study, among the first to explore circadian time mechanisms outside the brain, could have a potentially broad impact on the burgeoning fields of circadian medicine and postgenomic science. Clinicians have known for years that organs function at different rates—the heart beats, kidneys transport ions and electrolytes, the liver metabolizes lipids, sugars, and amino acids differently over the course of the day—and have used this knowledge to design more effective drug regimens for patients. A better understanding of what drives those local rhythms, and how they go wrong, could aid physicians’ efforts.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 1932 - Posted: 06.24.2010

— Researchers have traced the light-sensing circuitry for a type of “second sight” that is distinct from the conventional visual system and seems to interact directly with the body’s internal clock. The researchers speculate that subtle genetic malfunctions of this machinery might underlie some sleep disorders. In an article published in the February 8, 2002, Science, a research team led by Howard Hughes Medical Institute investigator King-Wai Yau described the circuitry, which consists of a subset of nerve cells that carry visual signals from the eye to the brain. The scientists showed that circadian-pacemaker nerve cells almost certainly depend on a different light-sensing pigment, called melanopsin, than the conventional visual system, which relies on rod and cone photoreceptors arrayed across the retina. ©2002 Howard Hughes Medical Institute

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: 1497 - Posted: 06.24.2010

Researchers in Sweden say there might be a link between constant summer sunlight and a high rate of suicide in Greenland, a finding that medical officials in northern Canada are watching. A team led by psychiatrist Karin Sparring Björkstn of the Karolinska Institutet looked at the seasonal variation of suicides throughout Greenland between 1968 and 2002. The team's findings, published in the journal BMC Psychiatry on Friday, found an increase in the number of suicides during the summer months in Greenland, with a peak in June. Björkstn told CBC News she was surprised by the findings, but believes the sunlight could be amplifying underlying mental health issues and other problems. "There are, of course, many reasons that people commit suicide. But in the summer, when you don't sleep for extended periods of time, or you sleep very little, you may lose judgment," she said. "Some people actually become manic or delirious and they really don't know what they are doing. Perhaps they didn't intend to commit suicide." In the north of the Arctic island, Björkstn said 82 per cent of suicides occurred during the long periods of 24-hour summer light. Björkstn's team also suggested that light-generated imbalances could lead to increased impulsiveness. © CBC 2009

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: Biological Basis of Behavioral Disorders
Link ID: 12837 - Posted: 06.24.2010

By Tina Hesman Saey Scientists are discovering how tiny clocks inside each cell can march to the beat of a master drummer in the brain. Chuwy/iStockphoto, illustration by T. Dube Timing is everything. Just ask a comedian, trapeze artist, Romeo and Juliet — or nearly any cell in your body. Ticking away inside almost all cells are tiny clocks composed of protein gears. Scientists have known that these molecular clocks govern the daily rhythms of life, from mealtimes and bedtimes to the rise and fall of hormone levels, body temperature and blood pressure. New research shows that circadian clocks, as the daily timekeepers are known, do more than just control day-to-day schedules. Such clocks, some scientists say, have the potential to play a role in nearly every biological function. Studies of bacteria, rodents and fruit flies suggest that circadian clocks may time processes as diverse as cellular division and aging. “When you start asking, ‘what does the clock control?’ you have to say, ‘everything,’” says Erik Herzog, a biologist at Washington University in St. Louis. Some of the new insights come from studying the brain’s master clock, a pair of structures known as the suprachiasmatic nucleus, or SCN, that set the body’s daily rhythms. Other work, meanwhile, suggests that the SCN is not a single monolithic clock but more a set of interrelated nodes that help coordinate clocks throughout the body. And still other researchers have found that the SCN may not even be the ultimate arbiter of the body’s time, and that other organs control biological rhythms on their own without much, if any, help from the SCN. © Society for Science & the Public 2000 - 2010

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 13909 - Posted: 06.24.2010

Ewen Callaway You might call it our circadian eye. A handful of retina cells sense light, not for vision, but instead to reset our body clocks each day. Killing off these cells in mice leaves their sight unharmed, but throws their clocks out of whack, two new studies show. Jolting these cells back into action might offer salvation to insomniacs, whose circadian cycles are slightly off, says Satchidananda Panda, a molecular biologist at the Salk Institute in San Diego, who led one study. Natural degeneration of these cells could also explain why insomnia often strikes the elderly. "Maybe we can develop an eye drug to reset your clock," he says. Alternatively, triggering the cells with extra-pale blue light – the wavelengths they're most sensitive to – could do the same trick, says Samer Hattar, a neuroscientist at Johns Hopkins University in Baltimore. Hattar's team identified the same role for the cells, which produce a recently-discovered light sensor called melanopsin. The first evidence for our circadian eye came in the 1920s, when an American physician noticed that congenitally blind mice can still dilate their pupils – a sign of light detection – despite lacking rods and cones, the photosensors that transform light to vision. © 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: 11703 - Posted: 06.24.2010

If your child is born in the winter or fall, it will have better long-range eyesight throughout its lifetime and less chance of requiring thick corrective glasses, predicts a Tel Aviv University investigation led by Dr. Yossi Mandel, a senior ophthalmologist in the Israel Defense Forces Medical Corps. Forming a large multi-center Israeli team, the scientists took data on Israeli youth aged 16-23 and retroactively correlated the incidence of myopia (short-sightedness) with their month of birth. The results were astonishing. Babies born in June and July had a 24% greater chance of becoming severely myopic than those born in December and January – the group with the least number of severely myopic individuals. The investigators say that this evidence is likely applicable to babies born anywhere in the world. The results of the study were published this month in the clinical eye journal Ophthalmology. The team interpolated data from a sample size of almost 300,000 young adults, making it one of the largest epidemiological surveys carried out in the world on any subject. Is this great disparity in eyesight related to one’s luck or astrological sign? “Nonsense,” balks study co-author Prof. Michael Belkin of Tel Aviv University’s Goldschleger Eye Research Institute, the most prominent eye research organization in Israel and the region. Belkin is also Incumbent to the Fox Chair of Ophthalmology and one of the founders and first director of the Goldschleger Institute, established more than 25 years ago at the Sheba Medical Center. In November Prof. Belkin will attend the annual American Academy of Ophthalmology conference in New Orleans, La. © PhysOrg.com 2003-2007

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: 10652 - Posted: 06.24.2010