Links for Keyword: Biological Rhythms

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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

Roxanne Khamsi Mice with a gene mutation that disrupts their sleep cycles show signs of hyperactivity and addictive tendencies, a new study reveals. Researchers say that such "manic" behaviour displayed by the animals bolsters the theory that glitches in the body's internal clock can cause psychiatric illnesses such as bipolar disorder. Mice that received injections of DNA to compensate for the mutated gene regained regular sleep cycles and showed normal behaviour. This type of gene therapy will not work to treat people with bipolar disorder anytime soon, researchers stress, but they believe genetic experiments in rodents will reveal the potential targets for psychiatric drug treatments. Colleen McClung at the University of Texas Southwestern Medical Center in Dallas, US, and colleagues conducted experiments on mice with a mutation in their Clock gene. This gene normally activates other genes in the cell – with a certain regularity and on a daily basis. The human version is thought to be responsible for many of our circadian rhythms, including our wake/sleep cycle. Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0609625104) © Copyright Reed Business Information Ltd

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: 10107 - Posted: 06.24.2010

The first gene known to control the internal clock of humans and other mammals works much differently than previously believed, according to a study by Utah and Michigan researchers. The surprising discovery means scientists must change their approach to designing new drugs to treat jet lag, insomnia, some forms of depression, sleep problems in shift workers and other circadian rhythm disorders, according to researchers at the University of Utah's Huntsman Cancer Institute and the University of Michigan, Ann Arbor. The study – which involved the so-called tau mutation that causes hamsters to have a 20-hour day instead of a 24-hour day – will be published online the week of July 3 in the journal Proceedings of the National Academy of Sciences. The researchers discovered that what was previously believed about the tau mutation – that a decrease in gene activity sped up a mammal's internal clock – was incorrect. Instead, the mutation caused an increase in gene activity to speed up the clock, making the day two to four hours shorter for affected animals. Previous work had indicated that the tau mutation occurred in a gene called casein kinase 1 epsilon (CK1) and that the mutation caused an 85 percent loss of gene activity. This, it was thought, explained why the hamster had a short day. But as it turns out, this idea was wrong.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 9090 - Posted: 06.24.2010

PORTLAND, Ore. – Research conducted at Oregon Health & Science University suggests that contrary to popular belief, the body has more than one "body clock." The previously known master body clock resides in a part of the brain called the suprachiasmatic nucleus (SCN). Researchers at OHSU's Oregon National Primate Research Center (ONPRC) have now revealed the existence of a secondary clock-like mechanism associated with the adrenal gland. The research also suggests a high likelihood that additional clocks exist in the body. The study results are printed in the current edition of the journal Molecular Endocrinology. "We're all familiar with the idea that the body has a master clock that controls sleep-wake cycles. In fact, most of us have witnessed the impacts of this clock in the form of jet lag where it takes the body a number of days to adjust to a new time schedule following a long flight," explained Henryk Urbanski, Ph.D., senior author of the study and a senior scientist at ONPRC. "Our latest research suggests that a separate but likely related clock resides in the adrenal gland. The adrenal gland is involved in several important body functions, such as body temperature regulation, metabolism, mood, stress response and reproduction. The research also suggests that other peripheral clocks reside throughout the body and that these clocks are perhaps interconnected." To conduct the research, scientists studied adrenal gland function in rhesus macaque monkeys which is very similar to human adrenal gland function. Specifically, researchers measured gene expression in the adrenal gland of monkeys during a 24-hour period (six times a day, four-hour intervals).

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 8948 - Posted: 06.24.2010

Gaia Vince Reindeer have a body clock that does not rely on a 24-hour day/night light cycle, according to Norwegian researchers. It may explain how they stay awake to carry out their Christmas duties. Instead, the herbivores’ stomachs seem to keep their body clocks ticking along. Karl-Arne Stokkan at the University of Tromsø, and colleagues, logged the festive animals’ movements every 10 minutes for a year using a radio transmitter device embedded in collars around the reindeers’ necks. The collars were placed on 12 reindeer – six who roamed a mountainous region of mainland Norway at a latitude of 70° North, and six found in the more-northerly Arctic archipelago of Svalbard (78° N). Winter in these regions is unyieldingly dark, while in summer the Sun does not set. Spring and autumn provide just a few weeks of night/day cycles. In the absence of light stimuli humans, like most mammals, naturally revert to a 6 to 8-hour sleep pattern due to an inbuilt circadian rhythm. © 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: 8330 - Posted: 06.24.2010

Temperature triggers significant changes in the expression of specific clock genes. The biological clock controls the circadian rhythms of a wide range of physiological and behavioral processes, from fluctuating hormone levels to sleep–wake cycles and feeding patterns. While it's well known that circadian clock elements sense and respond to light cycles, much less is known about how daily temperature cycles affect the clock's timing mechanism in vertebrates. In the open-access journal PLoS Biology, Kajori Lahiri, Nicholas Foulkes, and their colleagues study temperature related responses at the genetic and molecular level in zebrafish. This genetically tractable model organism is especially suited to this task because adults, larvae, and even embryos can tolerate a wide range of core body temperatures (being cold-blooded animals) that can be manipulated simply by changing the water temperature. Temperature variations of as little as 2 ºC (35.6 ºF) can reset the zebrafish clock, Lahiri et al. show, and precise shifts in temperature trigger significant changes in the expression of specific clock genes. More explicitly, clock genes per4, cry2a, cry3, and clock1 showed rhythmic expression under temperature cycles when animals were raised in the dark, and the expression profiles during the high temperature phase matched those seen during a light phase when animals experienced light-dark cycles.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 7958 - Posted: 06.24.2010

COLUMBUS , Ohio –- The brains of one species of mouse actually shrink during the winter, causing the mice to have more difficulty with some types of learning, a new study found. The results showed that, during the short days of winter, white-footed mice had impaired spatial memory – the mental map that helps them remember important places in their environment. This is one of the first studies to show seasonal changes in the structure and the functioning of brains of mammals, said Randy Nelson, co-author of the study and professor of psychology and neuroscience at Ohio State University. The changes in the brain may help the mice conserve energy to survive during the cold winter season when food is scarce and conditions are harsh. “The brain uses a lot of energy relative to its weight,” Nelson said. “Like many mammals, mice need to reduce their energy costs during winter, and the brain is a good place to do that.” And while there are obviously many differences between mice and humans, studies like this may one day help researchers gain insight into seasonal brain dysfunctions in humans such as seasonal affective disorder, Nelson said. Nelson conducted the study with Leah Pyter, a graduate student in neuroscience at Ohio State , and Brenda Reader, an undergraduate psychology major at Ohio State . The findings were published in the May 4 issue of the Journal of Neuroscience.

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: 7345 - Posted: 06.24.2010

A cluster of brain cells less than half the size of a pencil eraser tells you when to wake up, when to be hungry and when it's time to go to sleep. The same cells also cause you to be disoriented after you've flown across multiple time zones. The human circadian clock, comprised of about 20,000 time-keeping cells, has mystified scientists since it was pinpointed in the brain about 30 years ago. Now, a researcher at the University of Calgary is getting a little bit closer to understanding how it ticks. Dr. Michael Antle, a neuroscientist in the U of C's Department of Psychology, has conclusively shown that the 20,000 cells are organized in a complex network of groups that perform different functions – contrary to the previously held belief that each cell did the same thing. Antle, an emerging leader in the field, has two new papers on the subject: one is featured on the March cover of the prestigious Trends in Neurosciences, and another is due out in a forthcoming issue of the Journal of Neurosciences. "There are enormous health, safety and economic benefits to figuring out how the circadian clock works," Antle says. "We are probably still at least 10 years away from developing a pill that could reset your circadian clock to eliminate jet lag, but this new perspective in how the cells are organized definitely improves our understanding."

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 6993 - Posted: 06.24.2010

HOUSTON, – If you crammed for tests by pulling 'all nighters' in school, ever wonder why your memory is now a bit foggy on what you learned? A University of Houston professor may have the answer with his research on the role of circadian rhythms in long-term learning and memory. Arnold Eskin, the John and Rebecca Moores Professor of Biology and Biochemistry at UH, was recently awarded two grants totaling $2,472,528 from the National Institutes of Health (NIH) to continue pursuing his investigations of memory formation and the impact of the biological clock on learning and memory. Scientists have known for a while that the brain's biological (or circadian) clock influences natural body cycles, such as sleep and wakefulness, metabolic rate and body temperature. New research from Eskin suggests the circadian clock also may regulate the formation of memory at night. This new research focuses on "Circadian Modulation of Long-term Memory Formation" and "Long-term Regulation of Glutamate Uptake in Aplysia," with NIH funding to be disbursed over four years. "There is a lot of research going on in memory," Eskin said. "How do we remember things given that we don't have a camera in our brain to record events? What changes take place in our brains that allow us to remember? These grants are about fundamental learning and memory and about modulation of memory."

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: 6898 - Posted: 06.24.2010

Researchers have discovered that individual fibroblast cells contain independent, self-sustaining circadian (ca. 24 hr) clocks. Circadian clocks are important for synchronizing many physiological and behavioral processes to the day/night cycle. For decades it has been known that a tiny cluster of brain cells known as the suprachiasmatic nucleus (SCN) is required for expression of circadian rhythms in mammals. When clock genes were identified in the late '90s, they were found to be expressed rhythmically not only in SCN but also in many other tissues. Some of these studies used the firefly luciferase gene, introduced into cells with regulatory elements from a clock gene, so that cell cultures emitted light with a circadian rhythm. However, peripheral tissue rhythms tended diminish after a few cycles in culture, suggesting that they might depend on the central nervous system's SCN to drive them. In the new work, performed by researchers at The Scripps Research Institute and Northwestern University, Dr. David Welsh and colleagues used bioluminescence imaging to monitor circadian rhythms of clock gene expression from individual rat or mouse fibroblasts. Robust rhythms of single cells persisted without diminishing for at least 1–2 weeks in culture. Cells were partially synchronized by medium change at the start of an experiment, but because of different circadian periods drifted out of phase after several days, leading the ensemble rhythm to diminish. Thus, even cells outside the brain contain bona fide circadian clocks.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 6474 - Posted: 06.24.2010

CHICAGO – Patients with deficit schizophrenia, a subtype of schizophrenia characterized by "negative" symptoms, such as blunted speech and expression, lack of emotional response, and apathy, are more likely to have been born in the summer months, according to an article in the October issue of The Archives of General Psychiatry, one of the JAMA/Archives journals. According to the article, winter birth was reported to be a risk factor for schizophrenia in 1929. Clinical aspects of patients with schizophrenia born in the winter include paranoia and a more benign course of illness. Additionally, the clinical features associated with winter birth are different from patients with deficit schizophrenia, defined by the presence of negative symptoms, including inability to experience pleasure, lack of interest in socializing, speech deficits, blunted emotional response, poor eye contact, and more severe course of illness. Nondeficit schizophrenia is characterized by symptoms including hallucinations, incoherent thinking, and prominent delusions. Erick Messias, M.D., M.P.H., of The Johns Hopkins University, Baltimore, Md., and colleagues analyzed published and unpublished data from the northern hemisphere on studies of season of birth with information on schizophrenia and its subtype- deficit or nondeficit. A total of 1,594 patients were included in the nine studies examined.

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: 6194 - Posted: 06.24.2010

(Santa Barbara, Calif.) –– Our biological clock, or circadian rhythm, is upset by travelling across time zones, but very soon the body adjusts to the new day/night cycle. New studies of the computational models of the circadian rhythm of fruit flies show that the internal clock is robust, that is, not easily perturbed. These studies may eventually lead to greater understanding of human jet lag as well as human disease states. Engineers at the University of California, Santa Barbara's new Institute for Collaborative Biotechnologies and the Max Planck Institute (MPI) for Dynamics of Complex Technical Systems, in Magdeburg, Germany have analyzed the mechanism of genetic circuits by which the fruit fly regulates its circadian rhythm. The results are published in the August 30 Proceedings of the National Academies of Science. The mechanism controlling the biological clock generates a complicated dynamic behavior, oscillating back and forth and making it difficult to study, but also making it a good prototypical dynamic cellular system. The circadian rhythm of the fruit fly is a regulatory system that takes its cues from the sun. When the sun rises it affects the light-sensitive neurons of the brain of the fruit fly, setting off reactions of proteins at a certain rate depending on the amount of light. The reactions set the clock. There are key proteins and two key feedback loops involved, making the system a hierarchical control scheme, a design tool often used in engineering.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 6045 - Posted: 06.24.2010

Development of a molecular timetable by analysis of circadian gene expression – A look inside a wristwatch reveals that timekeeping is a complex affair, involving the coordination of mechanical parts providing the impulses and feedback needed to achieve precisely recurring movement. Biological clocks are equally complex, regulated by a network of genes and transcriptional factors that interact to stabilize the rhythms of numerous physiological systems. Unlike the wristwatch, however, there is no visible readout or display showing an individual's body time, a lack which has stood as one of the major barriers to realizing the promise of chronotherapy, which seeks to deliver drug treatments at optimal body times. A new study by Hiroki R. Ueda (Laboratory for Systems Biology, RIKEN Center for Developmental Biology; Kobe, Japan) and colleagues has provided proof of principle that just such a display of individual body time may one day possible. The report, published in the August 3 issue of the Proceedings of the National Academy of Sciences, describes the analysis of the expression of more than 100 time-indicating genes in the mouse. The results of this genome-wide study enabled the authors to develop a "molecular timetable" that provides an accurate representation of the animal's body time based on the sampling of gene expression levels at a single point in time.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 5995 - Posted: 06.24.2010

HANOVER, NH – While picking apart the genetic makeup of the plant Arabidopsis, two Dartmouth researchers made a startling discovery. They found that approximately 36 percent of its genome is potentially regulated by the circadian clock, which is three and a half times more than had previously been estimated. The study, which appears in the June issue of Plant Physiology, was conducted by C. Robertson McClung, Dartmouth professor of biological sciences, and Todd Michael, a former Dartmouth graduate student who is now a postdoctoral fellow at the Salk Institute in La Jolla, Calif. Their research on circadian-controlled genes contributes to efforts to help improve plant productivity and can possibly lead to growing crops that are more resistant to stressful soil or climate conditions. McClung and Michael used a technique called "gene trapping" or "enhancer trapping" to measure how much mRNA is produced or synthesized by large sections in the genome. According to McClung, a great deal of gene regulation occurs in the gene's ability to synthesize mRNA, which then is translated into proteins that perform the critical metabolic activities of a cell.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 3982 - Posted: 06.24.2010

COLLEGE STATION, – It may be only pond scum, the sort of green gunk that clogs lakes and floats in on the tides. But inside, a clock is quietly ticking. Even this lowly one-celled bacterium has a biological clock, the sophisticated internal timing device that governs the daily rhythms of people, animals and plants, says Susan Golden, a biology professor at Texas A&M University. The university’s Department of Biology is a leader in unraveling the mysteries of biological clocks, research that eventually could lead to cures for sleep and mood disorders, as well as other medical problems. Golden and her colleagues also study the biological clocks of birds, rats and fungi, but it was the bacterium known as Synechococcus elongatus that yielded the latest revelation: the first structural model of part of the clockworks.

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 3375 - Posted: 06.24.2010

WEST LAFAYETTE, Ind. – The biological clock – timekeeper for virtually every activity within living things, from sleep patterns to respiration – is a single protein, Purdue University researchers report. The husband and wife team of D. James and Dorothy Morré has discovered this protein, which is responsible for setting the length of periods of activity and inactivity within cells. If the protein is altered, an organism's body will experience "days" of different length – ranging from 22 to 42 hours in length in some cases. The discovery could have far-reaching implications for medicine. "We can now begin to understand the complex chain of events that connect the clock to events in the body," said James Morré ;, Dow Distinguished Professor of Medicinal Chemistry in Purdue's School of Pharmacy and Pharmacal Sciences. "Since the clock affects nearly every bodily activity, this discovery holds myriad potential applications, from minimizing jet lag to determining when best to administer cancer drugs."

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 3268 - Posted: 06.24.2010

New method shows electrical activity to be a central component of molecular clocks governing circadian rhythms Electrical excitability is harnessed by the body for a myriad of physiological functions including communication between nerve cells and regulation of heartbeat. Diseases caused by pathological electrical over-excitability, such as epilepsy and cardiac arrhythmia, can be catastrophic. A team of biologists at New York University has discovered a new and efficient method of “silencing” neurons – effectively blocking their electrical excitability – by introducing a new twist on a standard genetic technique. The new method sheds light on the central role electrical activity in neurons plays in governing the body’s circadian rhythms, or internal clock. It may also help in the future development of more effective treatments for diseases that are caused by aberrant electrical activity in neurons and other electrically excitable cells and tissues. The findings were published in the May 17 issue of Cell. Led by Todd C. Holmes, Assistant Professor of Biology at NYU, the team developed an experimental test case to control the electrical activity of a specific neural circuit in Drosophila by directing the expression of modified potassium channel genes. Potassium channels act as the “brakes” for electrical excitability.

Related chapters from BP7e: 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: 2085 - Posted: 06.24.2010

PHILADELPHIA – Working with sleep-deprived fruit flies, scientists at the University of Pennsylvania have uncovered the first molecular pathway, in any species, implicated in the shift between rest and wakefulness. The findings, from a team led by Joan C. Hendricks of Penn's Center for Sleep and Respiratory Neurobiology, are reported in the November issue of the journal Nature Neuroscience. The work indicates that a Drosophila melanogaster gene known as CREB – evolutionarily conserved in species from flies to humans – plays a role in rest's rejuvenating effects, apparently permitting sustained wakefulness. Anyone who's ever pulled an all-nighter knows by the next morning that sleep is essential, and sleep's status as a behavior found in organisms ranging from fruit flies to frogs to humans underscores its importance as a biological process. But 50 years after the discovery of REM sleep, scientists still know little, on a molecular level, about why sleep is needed and the exact benefits conferred by a daily period of rest

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
Link ID: 1022 - Posted: 06.24.2010

Neuroscientists at Jefferson Medical College have clarified how the human eye uses light to regulate melatonin production, and in turn, the body's biological clock. They have discovered what appears to be a fifth human "photoreceptor," and which is the main one to regulate the biological – and non-visual – effects of light on the body. They have identified a novel photopigment in the human eye responsible for reacting to light and controlling the production of melatonin, which plays an important role in the body's circadian rhythms. They also discovered that wavelengths of light in the blue region of the visible spectrum are the most effective in controlling melatonin production. ©2001 Thomas Jefferson University Hospital

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: 429 - Posted: 06.24.2010