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Circadian
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment ( entrained by the environment). These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in animals, plants, fungi and cyanobacteria. The term ''circadian'' comes from the Latin ''circa'', meaning "approximately", and ''dies'', meaning "day". Processes with 24-hour cycles are more generally called diurnal rhythms; diurnal rhythms should not be called circadian rhythms unless they can be confirmed as endogenous, and not environmental. Although circadian rhythms are endogenous, they are adjusted to the local environment by external cues called zeitgebers (German for "time givers"), which include light, temperature and redox cycles. In clinical settings, an abnormal circadian rhythm in humans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circadian Clock
A circadian clock, or circadian oscillator, is a biochemical oscillator that cycles with a stable phase (waves), phase and is synchronized with solar time. Such a clock's ''in vivo'' period is necessarily almost exactly 24 hours (the earth's current day, solar day). In most living things, internally synchronized circadian clocks make it possible for the organism to anticipate daily environmental changes corresponding with the day–night cycle and adjust its biology and behavior accordingly. The term circadian derives from the Latin ''circa'' (about) ''dies'' (a day), since when taken away from external cues (such as environmental light), they do not run to exactly 24 hours. Clocks in humans in a lab in constant low light, for example, will average about 24.2 hours per day, rather than 24 hours exactly. The normal body clock oscillates with an endogenous period of exactly 24 hours, it Entrainment (chronobiology), entrains, when it receives sufficient daily corrective signals from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circadian Rhythm Sleep Disorder
Circadian rhythm sleep disorders (CRSD), also known as circadian rhythm sleep-wake disorders (CRSWD), are a family of sleep disorders which affect the timing of sleep. CRSDs arise from a persistent pattern of sleep/wake disturbances that can be caused either by dysfunction in one's biological clock system, or by misalignment between one's endogenous oscillator and externally imposed cues. As a result of this mismatch, those affected by circadian rhythm sleep disorders have a tendency to fall asleep at unconventional time points in the day. These occurrences often lead to recurring instances of disturbed rest, where individuals affected by the disorder are unable to go to sleep and awaken at "normal" times for work, school, and other social obligations. Delayed sleep phase disorder, advanced sleep phase disorder, non-24-hour sleep–wake disorder and irregular sleep–wake rhythm disorder represents the four main types of CRSD. Overview Humans, like most living organisms, have v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colin Pittendrigh
Colin Stephenson Pittendrigh (October 13, 1918 – March 19, 1996) "Colin Pittendrigh, 'Father of biological clock,' dies at 77", March 25, 1996, accessed April 9, 2011. was a British-born who spent most of his adult life in the United States. Pittendrigh is regarded as the "father of the biological clock," and founded the modern field of alongside and Erwin Bünnin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeitgeber
A zeitgeber () is any external or environmental cue that entrains or synchronizes an organism's biological rhythms, usually naturally occurring and serving to entrain to the Earth's 24-hour light/dark and 12-month cycles. History The term ' (; ) was first used by Jürgen Aschoff, one of the founders of the field of chronobiology. His work demonstrated the existence of endogenous (internal) biological clocks, which synchronize biological rhythms. In addition, he found that certain exogenous (external) cues, which he called zeitgeber, influence the timing of these internal clocks. Photic and nonphotic zeitgebers * Light (light is a more important zeitgeber than social interactions). * Atmospheric conditions * Medication * Temperature * Social interactions * Exercise * Eating/drinking patterns Circadian rhythms Any biological process in the body that repeats itself over a period of approximately 24 hours and maintains this rhythm in the absence of external stimuli is considered a ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erwin Bünning
Erwin Bünning (23 January 1906 – 4 October 1990) was a German biologist. His most famous contributions were to the field of chronobiology, where he proposed a model for the endogenous circadian rhythms governing plant photoperiodism. From these contributions, Bünning is considered a co-founder of chronobiology along with Jürgen Aschoff and Colin Pittendrigh. Life Early life and education Bünning was born on 23 January 1906 in Hamburg, Germany to Heinrich Bünning and Hermine Bünning (born Winkler). A teacher of German, English, mathematics, and biology, Bünning's father was the primary academic influence on Erwin's early life, passing on to Erwin a passion for botany. Bünning received his primary education in Hamburg from 1912-1925. Bünning then attended the University of Göttingen and the University of Berlin from October 1925-July 1928, where he studied biology, chemistry, physics, and philosophy. Bünning earned his Doctorate of Philosophy from the University o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Jacques D'Ortous De Mairan
Jean-Jacques d'Ortous de Mairan (26 November 1678 – 20 February 1771) was a French geophysicist, astronomer and most notably, chronobiologist, was born in the town of Béziers on 26 November 1678. De Mairan lost his father, François d'Ortous, at age four and his mother twelve years later at age sixteen. Over the course of his life, de Mairan was elected into numerous scientific societies and made key discoveries in a variety of fields including ancient texts and astronomy. His observations and experiments also inspired the beginning of what is now known as the study of biological circadian rhythms. At the age of 92, de Mairan died of pneumonia in Paris on 20 February 1771. Biography De Mairan attended college in Toulouse from 1694–1697 with a focus in ancient Greek. In 1698 he went to Paris to study mathematics and physics under the teachings of Nicolas Malebranche. In 1702, he returned home to Béziers and began his lifelong study of several fields, most notably astr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrainment (chronobiology)
In the study of chronobiology, entrainment occurs when rhythmic physiological or behavioral events match their period to that of an environmental oscillation. It is ultimately the interaction between circadian rhythms and the environment. A central example is the entrainment of circadian rhythms to the daily light–dark cycle, which ultimately is determined by the Earth's rotation. Exposure to certain environmental stimuli will cue a phase shift, and abrupt change in the timing of the rhythm. Entrainment helps organisms maintain an adaptive phase relationship with the environment as well as prevent drifting of a free running rhythm. This stable phase relationship achieved is thought to be the main function of entrainment. There are two general modes of entrainment: phasic and continuous. The phasic mode is when there is limited interaction with the environment to "reset" the clock every day by the amount equal to the "error", which is the difference between the environmental cycle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sleep Deprivation
Sleep deprivation, also known as sleep insufficiency or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either chronic or acute and may vary widely in severity. Acute sleep deprivation is when an individual sleeps less than usual or does not sleep at all for a short period of time – usually lasting one to two days. Chronic sleep deprivation means when an individual routinely sleeps less than an optimal amount for ideal functioning. Chronic sleep deficiency is often confused with the term insomnia. Although both chronic sleep deficiency and insomnia share decreased quantity and/or quality of sleep as well as impaired function, their difference lies in the ability to fall asleep. Sleep deprived individuals are able to fall asleep rapidly when allowed but those with insomnia have difficulty falling asleep. The average adult needs seven or more hours of sleep per night to mainta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect. ''D. melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. ''D. melanogaster'' is a common pest in homes, restaurants, and othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franz Halberg
Franz Halberg (July 5, 1919 – June 9, 2013 ) was a scientist and one of the founders of modern chronobiology. He first began his experiments in the 1940s and later founded the Chronobiology Laboratories at the University of Minnesota. Halberg published many papers also in the serials of the History Commission of International Association of Geomagnetism and Aeronomy. He also published in "Wege zur Wissenschaft, Pathways to Science". He was a member of many international bodies, was awarded five honorary doctorates and was a member of the Leibniz Sozietät der Wissenschaften zu Berlin. In the 1950s, he introduced the word circadian, which derives from the Latin about (''circa'') a day (''diem''). Nominations for the Nobel Prize Halberg was nominated several times for the Nobel Prize in Physiology or Medicine. In 1988, and again in 1989, upon invitation by Professor Björn Nordenström of the Karolinska Institute in Sweden, then a member of the Nobel committee, Germaine Cornelis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ingeborg Beling
Ingeborg Beling (1904-1988) was a German Ethology, ethologist from the early 20th century who worked in the field of chronobiology. She studied at the University of Munich under the direction of Karl Von Frisch and is known for her research on the time sense of honey bees. In her research, in 1929, she trained bees to come to a feeding station at a specific time of day, day after day.Beling, Ingeborg.Über das Zeitgedächtnis der Bienen" Zeitschrift fur vergleichende Physiologie 9.2 (1929): 259-338. Print. This contribution ultimately led to the discovery of the bees’ 24-hour circadian rhythm, biological clock. Because of this achievement, she was regarded as one of the first female chronobiologists. Beyond honeybees, much of Beling's work involved studying behaviors of wasps, fly pupae, etc. Finally, she also did some research in pest control. Bee-feeding experiment (1929) Beling wrote in her widely cited 1929 paper, titled "''Über das Zeitgedächtnis der Bienen''" (“On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria. Cyanobacteria use photosynthetic pigments, such as carotenoids, phycobilins, and various forms of chlorophyll, which absorb energy from light. Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed. Phototrophic eukaryotes such as green plants perform photosynthesis in plast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
