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Mariah Quintanilla WASHINGTON, D.C. — If it takes you a while to recover from a few lost hours of sleep, be grateful you aren’t an orb weaver. Three orb-weaving spiders — Allocyclosa bifurca, Cyclosa turbinata and Gasteracantha cancriformis — may have the shortest natural circadian rhythms discovered in an animal thus far, researchers reported November 12 at the Society for Neuroscience’s annual meeting. Most animals have natural body clocks that run closer to the 24-hour day-night cycle, plus or minus a couple hours, and light helps reset the body’s timing each day. But the three orb weavers’ body clocks average at about 17.4, 18.5 and 19 hours respectively. This means the crawlers must shift their cycle of activity and inactivity — the spider equivalent of wake and sleep cycles — by about five hours each day to keep up with the normal solar cycle. “That’s like flying across more than five time zones, and experiencing that much jet lag each day in order to stay synchronized with the typical day-night cycle,” said Darrell Moore, a neurobiologist at East Tennessee State University in Johnson City. “Circadian clocks actually keep us from going into chaos,” he added. “Theoretically, [the spiders] should not exist.” For most animals, internal clocks help them perform recurring daily activities, like eat, sleep and hunt, at the most appropriate time of day. Previous studies have shown that animals that are out of sync with the 24-hour solar cycle are usually less likely to produce healthy offspring than those that aren’t. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24328 - Posted: 11.15.2017

By Angela Clow, Nina Smyth, October is a dismal time of year. The clocks go back, which accelerates the onset of darker evenings and the “shorter days” inevitably lead to calls for the tradition of putting clocks forward or backward to stop. Of course, the annual return to Greenwich Mean Time (GMT) from British Summer Time (BST) doesn’t make the days any shorter, it merely shifts an hour of available daylight from the evening to the morning. For many, lighter evenings are a priority and little attention is given to the benefits of lighter mornings. Arguments over clock changes tend to revolve around benefits for easier travel in lighter evenings. Nevertheless research suggests that holding onto lighter mornings might have hitherto unforeseen advantages. Light in the morning – more than any other time of day – leads to powerful brain-boosting effects, helping us to function as best we can, despite the approaching winter. All life on Earth has evolved around the 24-hour cycle of light and dark. An obvious sign is our desire for night-time sleep, but most biological functions are fine-tuned around day and night. Our bodies are honed to environmental light via a biological chain reaction. Light intensity is detected by special cells in the retina and this information is relayed to the internal body clock, located deep in a part of the brain called the suprachiasmatic nucleus. This sits in the hypothalamus, responsible for regulation of internal body processes using the endocrine system, which is linked to hormone secretion, via the pituitary gland. We are unaware of these light messages as they have nothing to do with conscious vision. Their sole job is to internalise information about environmental light intensity. © 2017 Scientific American,

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24261 - Posted: 10.30.2017

Nicola Davis Patients undergoing open heart surgery in the afternoon have a lower risk of potentially fatal complications than those undergoing operations in the morning, new research suggests. The study found that events including heart attacks and heart failure were less common among those who had undergone a valve replacement operation in the afternoon. The finding appears to be linked to the ability of the heart tissue to recover after being starved of blood supply during surgery – an effect the researchers say is influenced by the cells’ biological or “circadian” clock. Overweight patients less likely to die in hospital after heart operations Read more While the study suggests patients might fare better if they undergo afternoon surgery, Professor David Montaigne, first author of the research from the University of Lille in France, said it also highlighted another approach to reduce complications. “We have to find a drug that can alter the circadian clock to induce a jet lag,” he said, noting that it could also help to improve patient outcomes for heart attacks and organ transplantation. Writing the in Lancet, Montaigne and colleagues report how they looked at the outcomes of 596 patients, half of whom had valve surgery in the morning, and half in the afternoon. While 18% of morning surgery patients experienced a major cardiac event – such as a heart attack or heart failure –in the following 500 days, only 9% of those who had afternoon surgery experienced such events. © 2017 Guardian News and Media Limited

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24251 - Posted: 10.27.2017

By DOUGLAS QUENQUA Bad news, bears. Hibernation is no longer the coolest thing animals do to survive the winter. As cold weather approaches, tiny mole-like creatures known as red-toothed shrews will shrink their own heads, reducing their skull and brain mass by as much as 20 percent, according to new research published Monday in Current Biology. When warm weather returns, they will regrow the region nearly to its original size, giving new meaning to the phrase “spring ahead.” Though it is not yet clear why the shrews go down a few sizes for the winter, the authors of the study speculate that the reduced head and brain size helps them conserve energy when resources are scarce. “These tiny mammals cannot migrate long distances to avoid winter, nor can they enter any kind of energy-saving state” like hibernation, said Javier Lazaro, a doctoral student at the Max Planck Institute for Ornithology in Germany and an author of the study. They also have high metabolic rates and very little fat stored in their bodies. “Therefore, they starve within a few hours if they do not hunt constantly.” The researchers say the shrinkage is a survival strategy. “Brain tissue is energetically very expensive, so reducing overall brain size might decrease energy demands and thus food requirements,” he said. The shrews’ reduction in size doesn’t only affect the head. Several major organs lose mass in winter, and the spine shortens, as well. Overall, the shrews in the study reduced their body mass by about 18 percent from July to February. Previous research had hinted that all shrew species might undergo a reduction in body and head mass during the winter. There is even a term for it, Dehnel’s Phenomenon, named after the Polish zoologist who conducted that research, August Dehnel. © 2017 The New York Times Company

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 10: Biological Rhythms and Sleep
Link ID: 24236 - Posted: 10.24.2017

By Leslie Kaufman It is 7 p.m. on a spring Friday, and the Highland Hospital emergency room in Oakland, one of the busiest trauma centers in northern California, is expecting. When the patient—a young bicyclist hit by a car—arrives, blood is streaming down his temples. From a warren of care rooms, a team of nearly a dozen doctors and nurses materializes and buzzes around the patient. Amelia Breyre, a first-year resident who looks not much older than a college sophomore, immediately takes charge. As soon as the team finishes immobilizing the victim, Breyre must begin making split-second decisions: X-ray? Intubate? Transfusion? She quickly determines there is no internal bleeding or need for surgery and orders up neck X-rays after bandaging the patient’s head. Breyre will make a half-dozen similar critical choices tonight. Highland, a teaching hospital, is perhaps the most selective emergency-medical residency in the nation. To be here, she must be outstanding. To succeed, though, she must stay sharp. That quality of focus—amid the chaos and battered ­humanity that comes through Highland’s doors—is itself in need of urgent care. Andrew Herring, an emergency-room doctor who supervises Breyre and 40 other residents, is worried about the team. ER doctors are shift workers, and their hours are spread over a dizzying, ever-changing schedule of mornings, afternoons, and nights that total 20 ­different shifts a month. That’s meant to equally distribute the burden of nocturnal work across an entire team of physicians. But despite those good intentions, Herring says, the result is that every single one of them is exhausted and sleep ­deprived. That’s dangerous for doctor and patient alike.

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24165 - Posted: 10.09.2017

Allison Aubrey "With exquisite precision, our inner clock adapts our physiology to the dramatically different phases of the day," the Nobel Prize committee wrote of the work of Jeffrey C. Hall, Michael Rosbash and Michael W. Young. "The clock regulates critical functions such as behavior, hormone levels, sleep, body temperature and metabolism." We humans are time-keeping machines. And it seems we need regular sleeping and eating schedules to keep all of our clocks in sync. Studies show that if we mess with the body's natural sleep-wake cycle — say, by working an overnight shift, taking a trans-Atlantic flight or staying up all night with a new baby or puppy — we pay the price. Our blood pressure goes up, hunger hormones get thrown off and blood sugar control goes south. We can all recover from an occasional all-nighter, an episode of jet lag or short-term disruptions. But over time, if living against the clock becomes a way of life, this may set the stage for weight gain and metabolic diseases such as Type 2 diabetes. "What happens is that you get a total de-synchronization of the clocks within us," explains Fred Turek, a circadian scientist at Northwestern University. "Which may be underlying the chronic diseases we face in our society today." So consider what happens, for instance, if we eat late or in the middle of the night. The master clock — which is set by the light-dark cycle — is cuing all other clocks in the body that it's night. Time to rest. "The clock in the brain is sending signals saying: Do not eat, do not eat!" says Turek. But when we override this signal and eat anyway, the clock in the pancreas, for instance, has to start releasing insulin to deal with the meal. And, research suggests, this late-night munching may start to reset the clock in the organ. The result? Competing time cues. © 2017 npr

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24143 - Posted: 10.04.2017

Tina Hesman Saey Discoveries about the molecular ups and downs of fruit flies’ daily lives have won Jeffrey C. Hall, Michael Rosbash and Michael W. Young the Nobel Prize in physiology or medicine. These three Americans were honored October 2 by the Nobel Assembly at the Karolinska Institute in Stockholm for their work in discovering important gears in the circadian clocks of animals. The trio will equally split the 9 million Swedish kronor prize — each taking home the equivalent of $367,000. The researchers did their work in fruit flies. But “an awful lot of what was subsequently found out in the fruit flies turns out also to be true and of huge relevance to humans,” says John O’Neill, a circadian cell biologist at the MRC Laboratory of Molecular Biology in Cambridge, England. Mammals, humans included, have circadian clocks that work with the same logic and many of the same gears found in fruit flies, say Jennifer Loros and Jay Dunlap, geneticists at the Geisel School of Medicine at Dartmouth College. Circadian clocks are networks of genes and proteins that govern daily rhythms and cycles such as sleep, the release of hormones, the rise and fall of body temperature and blood pressure, as well as other body processes. Circadian rhythms help organisms, including humans, anticipate and adapt to cyclic changes of light, dark and temperature caused by Earth’s rotation. When circadian rhythms are thrown out of whack, jet lag results. Shift workers and people with chronic sleep deprivation experience long-term jet lag that has been linked to serious health consequences including cancer, diabetes, heart disease, obesity and depression. © Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24138 - Posted: 10.03.2017

Bill Chappell Jeffrey C. Hall, Michael Rosbash a and Michael W. Young are the joint winners of the 2017 Nobel Prize in Physiology or Medicine, winning for their discoveries about how internal clocks and biological rhythms govern human life. The three Americans won "for their discoveries of molecular mechanisms controlling the circadian rhythm" the Nobel Foundation says. From the Nobel Assembly at Karolinska Institutet, which announced the prize early Monday morning: "Using fruit flies as a model organism, this year's Nobel laureates isolated a gene that controls the normal daily biological rhythm. They showed that this gene encodes a protein that accumulates in the cell during the night, and is then degraded during the day. Subsequently, they identified additional protein components of this machinery, exposing the mechanism governing the self-sustaining clockwork inside the cell. We now recognize that biological clocks function by the same principles in cells of other multicellular organisms, including humans. "With exquisite precision, our inner clock adapts our physiology to the dramatically different phases of the day. The clock regulates critical functions such as behavior, hormone levels, sleep, body temperature and metabolism." Hall, 72, was born in New York and has worked at institutions from the University of Washington to the California Institute of Technology. For decades, he was on the faculty at Brandeis University in Waltham, west of Boston; more recently, he has been associated with the University of Maine. Rosbash, 73, was born in Kansas City, Mo., and studied at the Massachusetts Institute of Technology and at the University of Edinburgh in Scotland. Since 1974, he has been on faculty at Brandeis University in Waltham, Mass. Young, 68, was born in Miami, Fla., and earned his doctoral degree at the University of Texas in Austin. He then worked as a postdoctoral fellow at Stanford University in Palo Alto before joining the faculty at the Rockefeller University in 1978. © 2017 npr

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 24136 - Posted: 10.02.2017

Aaron E. Carroll Many high-school-aged children across the United States now find themselves waking up much earlier than they’d prefer as they return to school. They set their alarms, and their parents force them out of bed in the morning, convinced that this is a necessary part of youth and good preparation for the rest of their lives. It’s not. It’s arbitrary, forced on them against their nature, and a poor economic decision as well. The National Heart, Lung and Blood Institute recommends that teenagers get between nine and 10 hours of sleep. Most in the United States don’t. It’s not their fault. My oldest child, Jacob, is in 10th grade. He plays on the junior varsity tennis team, but his life isn’t consumed by too many extracurricular activities. He’s a hard worker, and he spends a fair amount of time each evening doing homework. I think most nights he’s probably asleep by 10 or 10:30. His school bus picks him up at 6:40 a.m. To catch it, he needs to wake up not long after 6. Nine hours of sleep is a pipe dream, let alone 10. There’s an argument to be made that we should cut back on his activities or make him go to bed earlier so that he gets more sleep. Teens aren’t wired for that, though. They want to go to bed later and sleep later. It’s not the activities that prevent them from getting enough sleep — it’s the school start times that require them to wake up so early. More than 90 percent of high schools and more than 80 percent of middle schools start before 8:30 a.m. Some argue that delaying school start times would just cause teenagers to stay up later. Research doesn’t support that idea. A systematic review published a year ago examined how school start delays affect students’ sleep and other outcomes. Six studies, two of which were randomized controlled trials, showed that delaying the start of school from 25 to 60 minutes corresponded with increased sleep time of 25 to 77 minutes per week night. In other words, when students were allowed to sleep later in the morning, they still went to bed at the same time, and got more sleep. © 2017 The New York Times Company

Related chapters from BN8e: 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: 24060 - Posted: 09.13.2017

Thomas Cronin We humans are uncommonly visual creatures. And those of us endowed with normal sight are used to thinking of our eyes as vital to how we experience the world. Vision is an advanced form of photoreception – that is, light sensing. But we also experience other more rudimentary forms of photoreception in our daily lives. We all know, for instance, the delight of perceiving the warm sun on our skin, in this case using heat as a substitute for light. No eyes or even special photoreceptor cells are necessary. But scientists have discovered in recent decades that many animals – including human beings – do have specialized light-detecting molecules in unexpected places, outside of the eyes. These “extraocular photoreceptors” are usually found in the central nervous system or in the skin, but also frequently in internal organs. What are light-sensing molecules doing in places beyond the eyes? Vision depends on detecting light All the visual cells identified in animals detect light using a single family of proteins, called the opsins. These proteins grab a light-sensitive molecule – derived from vitamin A – that changes its structure when exposed to light. The opsin in turn changes its own shape and turns on signaling pathways in photoreceptor cells that ultimately send a message to the brain that light has been detected. © 2010–2017, The Conversation US, Inc.

Related chapters from BN8e: 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: 23947 - Posted: 08.11.2017

By Linda Geddes BILLIONS of dollars have been spent in search of treatments for psychiatric conditions and brain disorders, when a cheap and effective drug may have been right under our noses: light. Now hospitals are turning to light to treat depression, strokes and Parkinson’s disease, using it to hit the reset button on our internal clocks. From green light soothing the pain of migraine, to blue light reducing organ damage during surgery, recent small studies have uncovered some intriguing effects of this therapy. But apart from easing seasonal affective disorder, we’ve been slow to embrace light as a serious contender for treating neurological conditions. We’ve known for 15 years that a special kind of receptor in our eyes transmits information directly to the body’s master clock, as well as other brain areas that control mood and alertness. These cells are particularly responsive to bluish light, including sunlight. These receptors enable light to act as a powerful reset switch, keeping the clock in our brain synced to the outside world. But this clock can fall out of sync or weaken as part of ageing or a range of disorders – a problem doctors are now starting to treat with light. Most hospitals have small windows and 24-hour lighting, both of which might exacerbate health problems. To tackle this, several hospitals in Europe and the US are installing dynamic “solid state” lighting, which changes like daylight over the course of a day. Such lights can, for example, shine bright whitish-blue in the morning, grow warmer and dimmer throughout the day, and turn orange or switch off at night. © Copyright New Scientist Ltd.

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 23808 - Posted: 07.06.2017

By Ashley Yeager Researchers led by Bert O’Malley of Baylor College of Medicine in Houston, Texas, identified a set of metabolism and stress genes in mouse liver cells that followed a pattern of expression on a 12-hour cycle—starting in the morning and again in the evening. O’Malley’s team also found that a 12-hour clock, distinct from the 24-hour circadian clock, drives this morning-evening rhythm in gene expression. The clock’s origin, the scientists suggest, may be rooted in organisms’ initial evolution in the ocean millions of years ago. “It’s a provocative argument,” Cambridge University biologist Michael Hastings tells The Scientist in a phone interview. He’s cautious about the claim of an evolutionary connection between the 12-hour clock in sea creatures and the 12-hour cycles seen in mammals. Still, he commends the team on taking a “cross-biology” approach toward exploring 12-hour gene-expression rhythms in a range of animals. In past studies, researchers have shown that coastal sea animals, such as the crustacean Eurydice pulchra have a dominant body clock driven by the 12-hour ebb and flow of the tides. Rhythms of gene expression every 12-hours have also been found in mammals, such as mice. Whether mammals’ 12-hour rhythms are driven by the body’s circadian clock or something else, however, has remained a mystery. Interested in that question and also observations that the time of day can affect humans’ ability to think clearly, handle stress, and respond to medicine, O’Malley and colleagues began to look more closely at mammals’ 12-hour gene-expression rhythms. In the new study, they analyzed gene-expression data of 18,108 mouse liver genes. Using a mathematical technique developed by researchers at Rice University, the team identified 3,652 genes that had 12-hour rhythms that didn’t appear to be associated with the mouse’s circadian clock. © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23748 - Posted: 06.17.2017

By Amina Zafar, CBC News When men postpone meal times, it delays one of the body's clocks, British researchers say, a finding that sheds light on a potential way to overcome jet lag and health harms for shift workers. Our bodies run a roughly 24-hour cycle called the circadian or sleep/wake rhythm. It is controlled by a master "clock" in the brain that responds to light signals from the retina, synchronizing other clocks throughout the body. Now investigators have discovered that a five-hour delay in meal time causes a five-hour delay in blood glucose rhythms. "We think this is due to changes in clocks in our metabolic tissues but not the 'master' clock in the brain," said Jonathan Johnston of the University of Surrey, one of the authors of the study published in Thursday's issue of the journal Current Biology. "This work is important because it demonstrates for the first time that a relatively subtle change of standard human feeding pattern re-synchronizes key metabolic rhythms in the body." Currently, people disoriented by the sluggish time warp of jet lag may take melatonin supplements and time their light exposure to help synchronize their clocks. While the study introduces the idea of adding meal timing to the clock reset toolkit, the practical details of how to do so still need to be worked out. In the experiment, 10 healthy young men came to a specialized sleep lab for 13 days. At first, breakfast was set for 30 minutes after waking. Then, after the men got used ©2017 CBC/Radio-Canada.

Related chapters from BN8e: 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: 23695 - Posted: 06.02.2017

By Jyoti Madhusoodanan For three consecutive winters, starting in 2011, researchers at the University of Birmingham asked healthy men and women over the age of 65 to come in to clinics across the western Midlands in the U.K. for a seasonal influenza vaccination at specific times of day—either between 9 and 11 a.m., or between 3 and 5 p.m. Blood drawn a month later revealed that participants, who totaled nearly 300 over the three years, had higher levels of anti-flu antibodies if they’d received their vaccinations in the morning.1 The results suggested that daily rhythms of people’s bodies tweaked the vaccine’s effectiveness. Lead author Anna Phillips Whittaker had suspected as much, after observing similar trends in her studies on behavioral factors such as exercise that affect vaccination responses, and in the wake of a growing body of literature suggesting that a little timing can go a long way when it comes to health. Many hormones and immune signals are produced rhythmically in 24-hour cycles. Cortisol, for example, which is known to suppress inflammation and regulate certain T cell–mediated immune responses, peaks early in the morning and ebbs as the day progresses. Other facets of the immune system undergo similar cycles that could underlie the differences in antibody responses Phillips observed among people receiving the flu vaccine. Much more work is required to nail down the immune mechanisms responsible for such variation and exploit them appropriately, she says. But timing flu vaccine delivery would be straightforward to implement. “It’s such a simple, low-risk intervention that’s free to do, and could have massive implications for vulnerable populations.” © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23484 - Posted: 04.13.2017

A gene variant may explain why some people prefer to stay up late and hate early mornings. The variant is a mutated form of the CRY1 gene, known to play a role in the circadian clock. Michael Young, at The Rockerfeller University, New York, and his team discovered the mutation in a person diagnosed with delayed sleep phase disorder – a condition that describes many so-called “night-owls”. The team found that five of this person’s relatives also had this mutation, all of whom had a history of sleep problems. They then studied six families in Turkey whose members included 39 carriers of the CRY1 variant. The sleep periods of those with the mutation was shifted by 2 to 4 hours, and some had broken, irregular sleep patterns. The mutation seems to slow the body’s internal biological clock, causing people to have a longer circadian cycle and making them stay awake later. The team have calculated that the variant may be present in as many as one in 75 people in some populations, such as Europeans of non-Finnish descent. But those who have a longer circadian cycle need not despair. Young says many people with delayed sleep phase disorder are able to control their sleep cycles by sticking to strict schedules. “It’s a bit like cigarette smoking in that there are things we can do to help the problem before turning to drugs,” he says. Journal reference: Cell, DOI: 10.1016/j.cell.2017.03.027 © Copyright Reed Business Information Ltd.

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23459 - Posted: 04.07.2017

By Jyoti Madhusoodanan The human body undergoes daily cycles in gene expression, protein levels, enzymatic activity, and overall function. Light is the strongest regulator of the central circadian rhythm. When light strikes a mammal’s eyes, it triggers an electrical impulse that activates neurons in the suprachiasmatic nucleus (SCN), the seat of the brain’s timekeeping machinery. The SCN sets the pace for neuronal and hormonal signals that regulate body temperature, feeding behavior, rest or activity, immune cell functions, and other daily activities, which in combination with direct signals from the SCN keep the body’s peripheral organs ticking in synchrony. Sunlight reaches the eyes, controls the central clock in the brain. The brain, in turn, controls different physiological processes, such as body temperature and rest-activity cycles, which then affect metabolites, hormones, the sympathetic nervous system, and other biological signals. These processes ensure that the different organ systems of the body cycle together. Timing Treatments to the Clock Regulated by peripheral clocks and interactions with other organs, many metabolic pathways in the body peak and ebb in specific circadian patterns. As a result, drugs targeting these pathways can work better when taken at particular times of day. Here are a few examples. © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23458 - Posted: 04.07.2017

Katherine Whalley The mammalian suprachiasmatic nucleus (SCN) can autonomously generate circadian oscillations in gene expression and neuronal activity, enabling it to fulfil its role as the brain's 'master circadian clock'. Although the contributions of specific neuronal populations to SCN function have begun to be elucidated, the potential influences of SCN astrocytes are relatively unexplored. Brancaccio et al. now reveal an important role for astrocyte–neuron signalling in SCN timekeeping. SCN neurons exhibit circadian oscillations in their intracellular calcium level ([Ca2+]i), peaking during the circadian 'day'. To determine whether similar fluctuations in activity are observed in astrocytes, the authors expressed a genetically encoded reporter of astrocytic [Ca2+]i in organotypic SCN slices. Long-term imaging revealed the presence of circadian oscillations in astrocytic [Ca2+]i, which was at its highest during the circadian 'night' and thus was anti-phasic to that of neurons. Astrocytes release 'gliotransmitters', including glutamate, in response to an increase in [Ca2+]i. When the authors expressed a genetically encoded sensor of the extracellular glutamate concentration ([Glu]e) in SCN slices, they observed circadian oscillations in [Glu]e that were in phase with astrocytic [Ca2+]i. oscillations. That astrocytes were the source of the measured [Glu]e was supported by the fact that the pharmacological inhibition of astrocytic glutamate catabolism or the genetic ablation of astrocytes, respectively, increased or reduced [Glu]e. © 2017 Macmillan Publishers Limited,

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 23436 - Posted: 04.01.2017

By STEPH YIN For animals that hibernate, making it to spring is no small feat. Torpor — the state of reduced bodily activity that occurs during hibernation — is not restful. By the time they emerge, hibernating animals are often sleep-deprived: Most expend huge bursts of energy to arouse themselves occasionally in the winter so their body temperatures don’t dip too low. This back-and-forth is exhausting, and hibernators do it with little to no food and water. By winter’s end, some have shed more than half their body weight. But just because it’s spring doesn’t mean it’s time to celebrate. Spring means getting ready for the full speed of summer — and after spending a season in slow motion, that requires some ramping up. Here’s a look at what different animals have on the agenda after coming out of winter’s slumber. Black bears emerge from their dens in April, but stay lethargic for weeks. During this so-called walking hibernation, they sleep plenty and don’t roam very far. Though they have lost up to one-third of their body weight over winter, they don’t have a huge appetite right away — their metabolism is not yet back to normal. They snack mostly on pussy willows and bunches of snow fleas. In January or February, some females give birth, typically to two or three cubs. New mothers continue to hibernate, but they go in and out of torpor, staying alert enough to respond to their cubs’ cries. When they emerge from their dens, mama bears find trees with rough bark that her cubs can easily climb for safety. “Slowly, the bears’ metabolism gears up to normal, active levels,” said Lynn Rogers, a bear expert and principal biologist at the Wildlife Research Institute, a nonprofit in Minnesota. “When plants start sprouting on the forest floor, that’s when they start really moving around.” © 2017 The New York Times Company

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23406 - Posted: 03.25.2017

By Diana Kwon Astrocytes, star-shape glial cells in the brain, were once simply considered support cells for neurons. However, neuroscientists have recently realized they have many other functions: studies have shown that astrocytes are involved in metabolism, learning, and more. In the latest study to investigate astrocytes’ roles in the brain, researchers confirmed these cells played a key role in regulating mouse circadian rhythms. The team’s results were published today (March 23) in Current Biology. “Recent results have indicated that [glia] are actively modulating synaptic transmission, the development of the nervous system, and changes in the nervous system in response to changes in the environment,” said coauthor Erik Herzog, a neuroscientist at Washington University in St. Louis. “So circadian biologists recognized that the system that we study in the brain also had astrocytes and have wondered what role that they might play.” In 2005, Herzog’s team published a seminal study linking glia to mammalian circadian rhythms. By investigating rat and mouse astrocytes in a dish, the researchers discovered that these glial cells showed circadian rhythms in gene expression. Since then, several independent groups have reported evidence to suggest that astrocytes help regulate daily rhythms. However, linking astrocytes to circadian behaviors in mice remained difficult. “I had several folks in the lab over many years [who] were unable to find the tools that would allow us to answer the question definitively: Do astrocytes play a role in scheduling our day?” Herzog recalled. “Then, within the last year or so, some new tools . . . became available for us.”. © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 23405 - Posted: 03.25.2017

Richard A. Friedman Jet lag makes everyone miserable. But it makes some people mentally ill. There’s a psychiatric hospital not far from Heathrow Airport that is known for treating bipolar and schizophrenic travelers, some of whom are occasionally found wandering aimlessly through the terminals. A study from the 1980s of 186 of those patients found that those who’d traveled from the west had a higher incidence of mania, while those who’d traveled from the east had a higher incidence of depression. I saw the same thing in one of my patients who suffered from manic depression. When he got depressed after a vacation to Europe, we assumed he was just disappointed about returning to work. But then he had a fun trip out West and returned home in what’s called a hypomanic state: He was expansive, a fount of creative ideas. It was clear that his changes in mood weren’t caused by the vacation blues, but by something else. The problem turned out to be a disruption in his circadian rhythm. He didn’t need drugs; he needed the right doses of sleep and sunlight at the right time. It turns out that that prescription could treat much of what ails us. Clinicians have long known that there is a strong link between sleep, sunlight and mood. Problems sleeping are often a warning sign or a cause of impending depression, and can make people with bipolar disorder manic. Some 15 years ago, Dr. Francesco Benedetti, a psychiatrist in Milan, and colleagues noticed that hospitalized bipolar patients who were assigned to rooms with views of the east were discharged earlier than those with rooms facing the west — presumably because the early morning light had an antidepressant effect. The notion that we can manipulate sleep to treat mental illness has also been around for many years. Back in the late 1960s, a German psychiatrist heard about a woman in Tübingen who was hospitalized for depression and claimed that she normally kept her symptoms in check by taking all-night bike rides. He subsequently demonstrated in a group of depressed patients that a night of complete sleep deprivation produced an immediate, significant improvement in mood in about 60 percent of the group. © 2017 The New York Times Company

Related chapters from BN8e: 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: 23350 - Posted: 03.13.2017