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Circadian
A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment). Circadian rhythms are regulated by a circadian clock whose primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximize the fitness of an individual. Circadian rhythms have been widely observed in animals, plants, fungi and cyanobacteria and there is evidence that they evolved independently in each of these kingdoms of life. The term ''circadian'' comes from the Latin ', meaning "around", and ', 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 adjuste ... [...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 that affect the timing of sleep. CRSDs cause a persistent pattern of sleep/wake disturbances that arise either by dysfunction in one's Circadian clock, biological clock system, or by misalignment between one's endogenous oscillator and externally imposed cues. As a result of this misalignment, those affected by circadian rhythm sleep disorders can fall asleep at unconventional time points in the day, or experience excessive daytime sleepiness if they resist. These occurrences often lead to recurring instances of disrupted rest and wakefulness, 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, irregular sleep–wake rhythm d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circadian Clock
A circadian clock, or circadian oscillator, also known as one’s internal alarm clock is a biochemical oscillator that cycles with a stable phase and is synchronized with solar time. Such a clock's ''in vivo'' period is necessarily almost exactly 24 hours (the earth's current solar day). In most living organisms, 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 entrains, when it receives sufficient daily corrective signals from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrainment (chronobiology)
In the study of chronobiology, entrainment refers to the synchronization of a biological clock to an environmental cycle. An example is the interaction between circadian rhythms and environmental cues, such as light and temperature. Entrainment helps organisms adapt their bodily processes according to the timing of a changing environment. For example, entrainment is manifested during travel between time zones, hence why humans experience jet lag. Biological rhythms are endogenous; they persist even in the absence of environmental cues as they are driven by an internal mechanism, most notably the circadian clock. Of the several possible cues (known as '' zeitgebers,'' German for 'time-givers') that can contribute to entrainment of the circadian clock, light has the greatest impact. Units of circadian time (CT) are used to describe entrainment to refer to the relationship between the rhythm and the light signal/pulse. Modes of entrainment There are two general modes of entrainm ... [...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 the most potent regulator of circadian rhythms). * 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 circ ... [...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 chronobiology alongside Jürgen Aschoff and Erwin Bünning. He is known for his careful descriptions of the pr ... [...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 ... [...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 (medicine), chronic or Acute (medicine), acute and may vary widely in severity. All known animals sleep or exhibit some form of sleep behavior, and the importance of sleep is self-evident for humans, as nearly a third of a person's life is spent sleeping. Sleep deprivation is common as it affects about one-third of the population. The National Sleep Foundation recommends that adults aim for 7–9 hours of sleep per night, while children and teenagers require even more. For healthy individuals with normal sleep, the appropriate sleep duration for school-aged children is between 9 and 11 hours. Acute sleep deprivation occurs when a person sleeps less than usual or does not sleep at all for a short period, typically lasting one to two days. However, if the slee ... [...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 natural philosopher (physicist), 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 on 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 astronomy and plant rhythms. Further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), 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", "pomace fly", or "banana fly". In the wild, ''D. melanogaster'' are attracted to rotting fruit and fermenting beverages, and are often found in orchards, kitchens and pubs. 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 theory, life history evolution. ''D. melanogaster'' was the first animal to be Fruit flies in space, launched into space in 1947. As of 2017, six Nobel Prizes have been awarded to drosophilists for their work using the insect. ''Drosophila melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with on ... [...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] |
Cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae. Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen, having appeared in the middle Archean eon and apparently originated in a freshwater or terrestrial environment. Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Kalmus
Hans may refer to: __NOTOC__ People * Hans (name), a masculine given name * Hans Raj Hans, Indian singer and politician ** Navraj Hans, Indian singer, actor, entrepreneur, cricket player and performer, son of Hans Raj Hans ** Yuvraj Hans, Punjabi actor and singer, son of Hans Raj Hans * Hans clan, a tribal clan in Punjab, Pakistan Places * Hans, Marne, a commune in France * Hans Island, administrated by Greenland and Canada Arts and entertainment * ''Hans'' (film) a 2006 Italian film directed by Louis Nero * Hans (Frozen), the main antagonist of the 2013 Disney animated film ''Frozen'' * ''Hans'' (magazine), an Indian Hindi literary monthly * ''Hans'', a comic book drawn by Grzegorz Rosiński and later by Zbigniew Kasprzak Other uses * Clever Hans, the "wonder horse" * ''The Hans India'', an English language newspaper in India * HANS device, a racing car safety device * Hans, the ISO 15924 code for Simplified Chinese characters See also *Han (other) Han may refer t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
