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Circadian rhythm

Circadian rhythm
Some features of the human circadian (24-hour) biological clock History[edit] The earliest recorded account of a circadian process dates from the 4th century B.C.E., when Androsthenes, a ship captain serving under Alexander the Great, described diurnal leaf movements of the tamarind tree.[1] The observation of a circadian or diurnal process in humans is mentioned in Chinese medical texts dated to around the 13th century, including the Noon and Midnight Manual and the Mnemonic Rhyme to Aid in the Selection of Acu-points According to the Diurnal Cycle, the Day of the Month and the Season of the Year.[2] The first recorded observation of an endogenous circadian oscillation was by the French scientist Jean-Jacques d'Ortous de Mairan in 1729. The term circadian was coined by Franz Halberg in the 1950s.[10] Criteria[edit] To be called circadian, a biological rhythm must meet these three general criteria:[11] Origin[edit] The simplest known circadian clock is that of the prokaryotic cyanobacteria.

Irregular sleep–wake rhythm Irregular sleep–wake rhythm is a rare form of circadian rhythm sleep disorder. It is characterized by numerous naps throughout the 24-hour period, no main nighttime sleep episode and irregularity from day to day.[1] Sufferers have no pattern of when they are awake or asleep, may have poor quality sleep, and often may be very sleepy while they are awake. The total time asleep per 24 hours is normal for the person's age.[2][3][4] The disorder is serious—an invisible disability. Nomenclature[edit] The current formally correct name of the disorder is Circadian Rhythm Sleep Disorder: Irregular Sleep Wake Rhythm Type.[5] This disorder has been referred to by many other terms, including: Irregular Sleep Wake Pattern,[6] irregular sleep wake syndrome,[7] Irregular Sleep Wake Rhythm,[8] Irregular Sleep Wake Cycle,[9] Irregular Sleep Wake Schedule[10] and Irregular Sleep Wake Disorder (ISWD).[4] Sometimes the words sleep and wake are hyphenated (sleep–wake). Causes[edit] Diagnosis[edit]

Mysterious Toe Rings Found on Ancient Egyptian Skeletons Archaeologists have discovered two ancient Egyptian skeletons, dating back more than 3,300 years, which were each buried with a toe ring made of copper alloy, the first time such rings have been found in ancient Egypt. The toe rings were likely worn while the individuals were still alive, and the discovery leaves open the question of whether they were worn for fashion or magical reasons. Supporting the magical interpretation, one of the rings was found on the right toe of a male, age 35-40, whose foot had suffered a fracture along with a broken femur above it. Unique rings in a unique ancient city Both skeletons were found in a cemetery just south of the ancient city of Akhetaten, whose name means "Horizon of the Aten." After Akhenaten's death, this attempt to change Egyptian religion unraveled, as his successors denounced him and the city became abandoned. The findings do appear to be the first copper alloy toe rings discovered in ancient Egypt. A magical healing device? Who were they?

Chronobiology Chronobiology is a field of biology that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms.[1] These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος (chrónos, meaning "time"), and biology, which pertains to the study, or science, of life. The related terms chronomics and chronome have been used in some cases to describe either the molecular mechanisms involved in chronobiological phenomena or the more quantitative aspects of chronobiology, particularly where comparison of cycles between organisms is required. Chronobiological studies include but are not limited to comparative anatomy, physiology, genetics, molecular biology and behavior of organisms within biological rhythms mechanics.[1] Other aspects include development, reproduction, ecology and evolution. Description[edit] The circadian rhythm can further be broken down into routine cycles during the 24-hour day:[2] History[edit]

Oldest Sequenced Genome Sheds Light on Horse Evolution When a horse gallops, there is a moment when all its feet leave the ground — the moment of suspension. Scientists digging for fossils in the permafrost of Canada's Yukon Territory happened across a different moment of suspension: a 700,000-year-old bone of an ancient colt, suspended and frozen in time beneath the ground. Luckily for the scientists, this icy grave kept the bone's proteins and DNA remarkably well-preserved. So well-preserved that the researchers were able to sequence its entire trove of genetic information, which has already begun shedding light on how horses evolved and how they are related to zebras, donkeys, and the Przewalski's horse — the last surviving type of wild horse. When researchers first found the leg bone, there were doubtful they'd be able to record its genome, the full collection of genetic information from an individual, said Ludovic Orlando, an evolutionary geneticist at the University of Copenhagen. Unraveling genetic mysteries The Przewalski's horse

Circadian rhythm sleep disorder Circadian rhythm sleep disorders (CRSD) are a family of sleep disorders affecting, among other things, the timing of sleep. People with circadian rhythm sleep disorders are unable to sleep and wake at the times required for normal work, school, and social needs. They are generally able to get enough sleep if allowed to sleep and wake at the times dictated by their body clocks. Unless they also have another sleep disorder, their sleep is of normal quality. Humans, like most animals and plants, have biological rhythms, known as circadian rhythms, which are controlled by a biological clock and work on a daily time scale. Sleep researcher Yaron Dagan states that "[t]hese disorders can lead to harmful psychological and functional difficulties and are often misdiagnosed and incorrectly treated due to the fact that doctors are unaware of their existence Types of circadian rhythm sleep disorders[edit] Extrinsic type[edit] Intrinsic type[edit] Normal circadian rhythms[edit] See also[edit]

The Experience and Perception of Time What is ‘the perception of time’? The very expression ‘the perception of time’ invites objection. Insofar as time is something different from events, we do not perceive time as such, but changes or events in time. But, arguably, we do not perceive events only, but also their temporal relations. So, just as it is natural to say that we perceive spatial distances and other relations between objects (I see the dragonfly as hovering above the surface of the water), it seems natural to talk of perceiving one event following another (the thunderclap as following the flash of lightning), though even here there is a difficulty. Kinds of temporal experience There are a number of what Ernst Pöppel (1978) calls ‘elementary time experiences’, or fundamental aspects of our experience of time. Duration One of the earliest, and most famous, discussions of the nature and experience of time occurs in the autobiographical Confessions of St Augustine. The specious present Here is one attempt to do so. Φ-β-κ

Excessive daytime sleepiness Excessive daytime sleepiness (EDS) is characterized by persistent sleepiness and often a general lack of energy, even after apparently adequate or even prolonged night time sleep. EDS can be considered as a broad condition encompassing several sleep disorders where increased sleep is a symptom, or as a symptom of another underlying disorder like narcolepsy, sleep apnoea or a circadian rhythm disorder. Some persons with EDS, including those with hypersomnias like narcolepsy and idiopathic hypersomnia, are compelled to nap repeatedly during the day; fighting off increasingly strong urges to sleep during inappropriate times such as while driving, while at work, during a meal, or in conversations. As the compulsion to sleep intensifies, the ability to complete tasks sharply diminishes, often mimicking the appearance of intoxication. Diagnosis[edit] A number of tools for screening for EDS have been developed. Causes[edit] EDS can be a symptom of a number of factors and disorders.

The Dark Side of the Nobel Prizes | Alfred Nobel For more than 100 years, the Nobel Prizes have recognized the finest in human achievements, from literature and science to the Nobel Peace Prize, which is given "to the person who shall have done the most or the best work for fraternity between nations, the abolition or reduction of standing armies and for the holding and promotion of peace congresses," according to the last will and testament of founder Alfred Nobel. But the origins of the Nobel Prizes, and the life of Alfred Nobel, tell a very different story, one tainted by the deaths of untold thousands of people. Alfred Bernhard Nobel was born in 1833 in Stockholm, Sweden. Finally achieving a measure of success, Immanuel brought his wife and eight children to St. Because the elder Nobel disapproved of Alfred's interest in poetry, he sent his son abroad to further his training in chemistry and engineering. Innovation from tragedy The invention of dynamite revolutionized the mining, construction and demolition industries.

Non-24-hour sleep-wake disorder Non-24-hour sleep–wake disorder (non-24), is one of several types of chronic circadian rhythm sleep disorders (CRSDs). It is defined as a "complaint of insomnia or excessive sleepiness related to abnormal synchronization between the 24-hour light–dark cycle and the endogenous circadian rhythms of sleep and wake propensity."[1] Symptoms result when the non-entrained (free-running) endogenous circadian rhythm drifts out of alignment with the desired or conventional sleep–wake schedule. However, the sleep pattern can be quite variable; some individuals adopt a sleep pattern that is congruent with their free-running circadian clock, shifting their sleep times (usually later), thereby minimizing their sleep symptoms but suffering major social and occupational consequences. Though often referred to as non-24, it is also known by the following terms: Mechanisms[edit] The circadian clock modulates many physiological rhythms. Characteristics[edit] Sighted[edit] Blind[edit] Symptoms[edit] Blind[edit]

SkyTools 3 by Skyhound Not All Astronomy Software is the Same It's the Astronomy that matters Planetarium programs that display the sky are a dime a dozen these days. They can be found on every platform, including your phone. But as useful as displaying the sky on your mobile device can be, it doesn’t directly help you figure out what objects you should be observing. For that you need observation planning. Traditionally amateur astronomers have picked objects from guide books, observed them at the time of year indicated, and waited until they were high enough above the horizon to observe. There are programs designed for observation planning, with spreadsheets of data and complicated graphics. It is the astronomy that separates SkyTools from planetariums and the spreadsheet planners. SkyTools is a complete observing system. To see the core of the SkyTools approach feel free to download the free trial of the Starter Edition. Below are some of the things that make SkyTools stand head and shoulders above the rest.

B-Society | B for Balance Welcome to the NSO | NSO Sleep diary A sleep diary with nighttime in the middle and the weekend in the middle, to better notice trends A sleep diary is a record of an individual's sleeping and waking times with related information, usually over a period of several weeks. It is self-reported or can be recorded by a care-giver. The sleep diary, or sleep log, is a tool used by doctors and patients.[1][2][3] It is a useful resource in the diagnosis and treatment of especially circadian rhythm sleep disorders, and in monitoring whether treatment of those and other sleep disorders is successful. Sleep diaries may be used in conjunction with actigraphy. In addition to being a useful tool for medical professionals in the diagnosis of sleep problems, a sleep diary can help make individuals more aware of the parameters affecting their sleep. Components[edit] The information contained in a sleep diary includes some or all of the following points: Data collection[edit] References[edit] Samples diaries[edit] External links[edit]