Altruism is the principle and moral practice of concern for happiness of other human beings and/or animals, resulting in a quality of life both material and spiritual. It is a traditional virtue in many cultures and a core aspect of various religious traditions and secular worldviews, though the concept of "others" toward whom concern should be directed can vary among cultures and religions. In an extreme case, altruism may become a synonym of selflessness, the opposite of selfishness. In a common way of living, it doesn't deny the singular nature of the subject, but realizes the traits of the individual personality in relation to the others, with a true and personal interaction with each of them, it is focusing both on the whole community. In a Christian practice, it is the law of love direct to his neighbour; the word "altruism" was coined by the French philosopher Auguste Comte in French, as altruisme, for an antonym of egoism. He derived it from the Italian altrui, which in turn was derived from Latin alteri, meaning "other people" or "somebody else".
Altruism in biological observations in field populations of the day organisms is an individual performing an action, at a cost to themselves, but benefits, either directly or indirectly, another third-party individual, without the expectation of reciprocity or compensation for that action. Steinberg suggests a definition for altruism in the clinical setting, "intentional and voluntary actions that aim to enhance the welfare of another person in the absence of any quid pro quo external rewards". Altruism can be distinguished from feelings of loyalty, in that whilst the latter is predicated upon social relationships, altruism does not consider relationships. Much debate exists as to; the theory of psychological egoism suggests that no act of sharing, helping or sacrificing can be described as altruistic, as the actor may receive an intrinsic reward in the form of personal gratification. The validity of this argument depends on whether intrinsic rewards qualify as "benefits"; the term altruism may refer to an ethical doctrine that claims that individuals are morally obliged to benefit others.
Used in this sense, it is contrasted with egoism, which claims individuals are morally obligated to serve themselves first. The concept has a long history in ethical thought; the term was coined in the 19th century by the founding sociologist and philosopher of science, Auguste Comte, has become a major topic for psychologists, evolutionary biologists, ethologists. Whilst ideas about altruism from one field can affect the other fields, the different methods and focuses of these fields always lead to different perspectives on altruism. In simple terms, altruism is acting to help them. Marcel Mauss's book The Gift contains a passage called "Note on alms"; this note describes the evolution of the notion of alms from the notion of sacrifice. In it, he writes: Alms are the fruits of a moral notion of the gift and of fortune on the one hand, of a notion of sacrifice, on the other. Generosity is an obligation, because Nemesis avenges the poor and the gods for the superabundance of happiness and wealth of certain people who should rid themselves of it.
This is the ancient morality of the gift. The gods and the spirits accept that the share of wealth and happiness, offered to them and had been hitherto destroyed in useless sacrifices should serve the poor and children. Compare Altruism – perception of altruism as self-sacrifice. Compare explanation of alms in various scriptures. In the science of ethology, more in the study of social evolution, altruism refers to behaviour by an individual that increases the fitness of another individual while decreasing the fitness of the actor. In evolutionary psychology this may be applied to a wide range of human behaviors such as charity, emergency aid, help to coalition partners, courtship gifts, production of public goods, environmentalism. Theories of altruistic behavior were accelerated by the need to produce theories compatible with evolutionary origins. Two related strands of research on altruism have emerged from traditional evolutionary analyses and from evolutionary game theory a mathematical model and analysis of behavioural strategies.
Some of the proposed mechanisms are: Kin selection. That animals and humans are more altruistic towards close kin than to distant kin and non-kin has been confirmed in numerous studies across many different cultures. Subtle cues indicating kinship may unconsciously increase altruistic behavior. One kinship cue is facial resemblance. One study found that altering photographs so that they more resembled the faces of study participants increased the trust the participants expressed regarding depicted persons. Another cue is having the same family name if rare, this has been found to increase helpful behavior. Another study found more cooperative behavior the greater the number of perceived kin in a group. Using kinship terms in political speeches increased audience agreement with the speaker in one study; this effect was strong for firstborns, who are close to their families. Vested interests. People are to suffer if their friends and similar social ingroups suffer or disappear. Helping such group members may therefore benefit the altruist.
Making ingroup membership more no
Beta wave, or beta rhythm, is a neural oscillation in the brain with a frequency range of between 12.5 and 30 Hz. Beta waves can be split into three sections: Low Beta Waves. Beta states are the states associated with normal waking consciousness. Beta waves were discovered and named by the German psychiatrist Hans Berger, who invented electroencephalography in 1924, as a method of recording electrical brain activity from the human scalp. Berger termed the larger amplitude, slower frequency waves that appeared over the posterior scalp when the subject's eye were closed alpha waves; the smaller amplitude, faster frequency waves that replaced alpha waves when the subject opened his or her eyes were termed beta waves. Low amplitude beta waves with multiple and varying frequencies are associated with active, busy or anxious thinking and active concentration. Over the motor cortex beta waves are associated with the muscle contractions that happen in isotonic movements and are suppressed prior to and during movement changes.
Bursts of beta activity are associated with a strengthening of sensory feedback in static motor control and reduced when there is movement change. Beta activity is increased when movement has to be voluntarily suppressed; the artificial induction of increased beta waves over the motor cortex by a form of electrical stimulation called Transcranial alternating-current stimulation consistent with its link to isotonic contraction produces a slowing of motor movements. Investigations of reward feedback have revealed two distinct beta components. In association with unexpected gains, the high beta component is more profound when receiving an unexpected outcome, with a low probability; however the low beta component is said to be related to the omission of gains, when gains are expected. Beta waves are considered indicative of inhibitory cortical transmission mediated by gamma aminobutyric acid, the principal inhibitory neurotransmitter of the mammalian nervous system. Benzodiazepines, drugs that modulate GABAA receptors, induce beta waves in EEG recordings from humans and rats.
Spontaneous beta waves are observed diffusely in scalp EEG recordings from children with duplication 15q11.2-q13.1 syndrome who have duplications of GABAA receptor subunit genes GABRA5, GABRB3, GABRG3. Children with deletions of the same GABAA receptor subunit genes feature diminished beta amplitude. Thus, beta waves are biomarkers of GABAergic dysfunction in neurodevelopmental disorders caused by 15q deletions/duplications. Delta wave – Theta wave – Alpha wave – Mu wave – Beta wave – Gamma wave –
Alpha waves are neural oscillations in the frequency range of 8–12 Hz arising from the synchronous and coherent electrical activity of thalamic pacemaker cells in humans. They are called Berger's waves after the founder of EEG. Alpha waves are one type of brain waves detected either by electroencephalography or magnetoencephalography, can be quantified using quantitative electroencephalography, they predominantly originate from the occipital lobe during wakeful relaxation with closed eyes. Alpha waves are reduced with open eyes and sleep, they were thought to represent the activity of the visual cortex in an idle state. More recent papers have argued that they inhibit areas of the cortex not in use, or alternatively that they play an active role in network coordination and communication. Occipital alpha waves during periods of eyes closed. An alpha-like variant called. Alpha waves were discovered by German neurologist Hans Berger, the inventor of the EEG itself. Alpha waves were among the first waves documented by Berger, along with beta waves, he displayed an interest in "alpha blockage", the process by which alpha waves decrease and beta waves increase upon a subject opening their eyes.
This distinction earned the alpha wave the alternate title of "Berger's Wave". Berger took a cue from Ukrainian physiologist Vladimir Pravdich-Neminsky, who used a string galvanometer to create a photograph of the electrical activity of a dog's brain. Using similar techniques, Berger confirmed the existence of electrical activity in the human brain, he first did this by presenting a stimulus to hospital patients with skull damage and measuring the electrical activity in their brains. He ceased the stimulus method and began measuring the natural rhythmic electrical cycles in the brain; the first natural rhythm he documented was. Berger was thorough and meticulous in his data-gathering, but despite his brilliance, he did not feel confident enough to publish his discoveries until at least five years after he had made them. In 1929, he published his first findings on alpha waves in the journal Archiv für Psychiatrie, he was met with derision for his EEG technique and his subsequent alpha and beta wave discoveries.
His technique and findings did not gain widespread acceptance in the psychological community until 1937, when he gained the approval of the famous physiologist Lord Adrian, who took a particular interest in alpha waves. Alpha waves again gained recognition in the early 1960s and 1970s with the creation of a biofeedback theory relating to brain waves; such biofeedback, referred to as a kind of neurofeedback, relating to alpha waves is the conscious elicitation of alpha brainwaves by a subject. Two researchers in the United States explored this concept through unrelated experiments. Joe Kamiya, of the University of Chicago, discovered that some individuals had the conscious ability to recognize when they were creating alpha waves, could increase their alpha activity; these individuals were motivated through a reward system from Kamiya. The second progenitor of biofeedback is Barry Sterman, from the University of California, Los Angeles, he was working with monitoring brain waves in cats and found that, when the cats were trained to withhold motor movement, they released SMR, or mu, waves, a wave similar to alpha waves.
Using a reward system, he further trained these cats to enter this state more easily. He was approached by the United States Air Force to test the effects of a jet fuel, known to cause seizures in humans. Sterman tested the effects of this fuel on the previously-trained cats, discovered that they had a higher resistance to seizures than non-trained cats. Alpha wave biofeedback has gained interest for having some successes in humans for seizure suppression and for treatment of depression; some researchers posit that there are at least two forms of alpha waves, which may have different functions in the wake-sleep cycle. Alpha waves are present at different stages of the wake-sleep cycle; the most researched is during the relaxed mental state, where the subject is at rest with eyes closed, but is not tired or asleep. This alpha activity is centered in the occipital lobe, is presumed to originate there, although there has been recent speculation that it instead has a thalamic origin; this wave begins appearing at around four months, is a frequency of 4 waves per second.
The mature alpha wave, at 10 waves per second, is established by age 3. The second occurrence of alpha wave activity is during REM sleep; as opposed to the awake form of alpha activity, this form is located in a frontal-central location in the brain. The purpose of alpha activity during REM sleep has yet to be understood. There are arguments that alpha patterns are a normal part of REM sleep, for the notion that it indicates a semi-arousal period, it has been suggested. It has long been believed; this has been attributed to studies where subjects report non-refreshing sleep and have EEG records reporting high levels of alpha intrusion into sleep. This occurrence is known as alpha wave intrusion. However, it is possible that these explanations may be misleading, as they only focus on alpha waves being generated from the occipital lobe. Alpha wave intrusion occurs when alpha waves appear with non-REM sleep when delta activity is expected, it is hypothesized to be associated with fibromyalgia, although the study may be inadequate due to a small sampling size.
Despite this, alpha wave i
Ludwig Bemelmans was an Austrian-born American writer and illustrator of children's books. He is known best for the Madeline picture books. Six were published since 1939. Bemelmans was born to the Belgian painter Lambert Bemelmans and the German Frances Fischer in Meran, Austria-Hungary, his father owned a hotel. He grew up in Gmunden on the Traunsee in Upper Austria, his first language was his second German. In 1904, his father left his wife and Ludwig’s governess, both of whom were pregnant with his child, for another woman, after which his mother took Ludwig and his brother to her native city of Regensburg, Germany. Bemelmans had difficulty in school, he was apprenticed to his uncle Hans Bemelmans at a hotel in Austria. In a 1941 New York Times interview with Robert van Gelder, he related that while an apprentice, he was beaten and whipped by the headwaiter. According to Bemelmans, He warned the headwaiter that if he was whipped again he would retaliate with a gun; the headwaiter ignored his warning, whipped him, Bemelmans shot and wounded him in retaliation.
Given the choice between reform school and emigration to the United States, he chose the latter. It is this was one of Bemelman’s famous yarns, since in John Bemelmans Marciano’s biography of his grandfather, he relates a simpler story: recognizing that Ludwig was an incorrigible boy, his uncle offered him the choice of going to America, or going to reform school, he spent the next several years working at hotels and restaurants in the US. In 1917, he joined the U. S. Army but was not sent to Europe because of his German origins, he did became an officer, was promoted to Second Lieutenant. He writes of his experiences in the Army in the book, My War With the United States. In 1918, he became a US citizen. In the 1920s, Bemelemans tried to become an artist and painter while working at hotels, but had substantial difficulties. In 1926, he quit his job at the Ritz Carlton in New York to become a full time cartoonist, his cartoon series The Thrilling Adventures of the Count Bric a Brac was dropped from the New York World after six months.
He associated with Ervine Metzl, a commercial artist and illustrator, variously described as Bemelmans's friend, "agent", "ghost artist". In the early 1930s Bemelmans met May Massee, the children's book editor at Viking Press, who became a sort of partner, he began to publish children's books, beginning with Hansi in 1934. He published the first Madeline book in 1939; the book was a great success. Bemelmans did not write a second Madeline book until 1953. Four more books in the series were subsequently published while he was alive, one more was published posthumously in 1999. Up until the early 1950s, the artistic media he worked in were pen and ink, water color, gouache; as he describes in his autobiographical My Life in Art, he had avoided oil painting because it did not permit him to produce artistic pieces quickly. But at this point in his life, he wanted to master the richness of oil painting. To this end, he set out to buy a property in Paris’s that would serve as a serious, full-blown art studio.
In 1953, he fell in love with a small bistro in Paris, La Colombe in the Ile de la Cité, bought it, intending to convert it into a studio. He painted murals therein, but the project was a disaster owing to French bureaucracy, after two years of frustration and disappointment, he unloaded it by selling it to Michel Valette, who converted it into a notable cabaret. Bemelmans wrote a number of adult books, including travel, humorous works and novels, as well as movie scripts; the latter included the Thief. While spending time in Hollywood, he became a close friend of interior decorator Elsie de Wolfe, Lady Mendl. A mural on the walls of the Carlyle Hotel's Bemelmans Bar in New York City, Central Park, is his only artwork on display to the public, he painted the children's dining room on Aristotle Onassis's yacht Christina, for the young daughter of the magnate, Christina Onassis. Each Madeline story begins: "In an old house in Paris, covered with vines, lived twelve little girls in two straight lines... the smallest one was Madeline."
The girls are cared for by Miss Clavel. She is a nun, as some French orders called themselves Madames that of St. Madeleine Sophie Barat, after which this convent school seems to be modeled; some have argued. Other characters include son of the Spanish ambassador, who lives next door. Bemelmans published six Madeline stories in his lifetime, five as picture books and one in a magazine. A seventh was discovered after his death and published posthumously: Madeline, 1939: in which Madeline must have her appendix removed Madeline's Rescue, 1953: in which Madeline is rescued from drowning by a dog. Winner of the Caldecott Medal for U. S. picture book illustration Madeline and the Bad Hat, 1956: in which the "bad hat" is Pepito, the Spanish ambassador's son, whose cruel antics outrage Madeline. Madeline and the Gypsies, 1959: in which Madeline and Pepito have an adventure at a circus. Madeline in London, 1961: in which Pepito moves to London, Madeline and the girls go to visit him. Madeline's Christmas, 1985: in which everyone in t
Racism is the belief in the superiority of one race over another, which results in discrimination and prejudice towards people based on their race or ethnicity. The use of the term "racism" does not fall under a single definition; the ideology underlying racism includes the idea that humans can be subdivided into distinct groups that are different due to their social behavior and their innate capacities, as well as the idea that they can be ranked as inferior or superior. Historical examples of institutional racism include the Holocaust, the apartheid regime in South Africa and segregation in the United States, slavery in Latin America. Racism was an aspect of the social organization of many colonial states and empires. While the concepts of race and ethnicity are considered to be separate in contemporary social science, the two terms have a long history of equivalence in both popular usage and older social science literature. "Ethnicity" is used in a sense close to one traditionally attributed to "race": the division of human groups based on qualities assumed to be essential or innate to the group.
Therefore and racial discrimination are used to describe discrimination on an ethnic or cultural basis, independent of whether these differences are described as racial. According to a United Nations convention on racial discrimination, there is no distinction between the terms "racial" and "ethnic" discrimination; the UN convention further concludes that superiority based on racial differentiation is scientifically false, morally condemnable unjust and dangerous. It declared that there is no justification for racial discrimination, anywhere, in theory or in practice. Racist ideology can manifest in many aspects of social life. Racism can be present in social actions, practices, or political systems that support the expression of prejudice or aversion in discriminatory practices or laws. Associated social actions may include nativism, otherness, hierarchical ranking and related social phenomena. In the 19th century, many scientists subscribed to the belief that the human population can be divided into races.
The term racism is a noun describing the state of being racist, i.e. subscribing to the belief that the human population can or should be classified into races with differential abilities and dispositions, which in turn may motivate a political ideology in which rights and privileges are differentially distributed based on racial categories. The origin of the root word "race" is not clear. Linguists agree that it came to the English language from Middle French, but there is no such agreement on how it came into Latin-based languages. A recent proposal is that it derives from the Arabic ra's, which means "head, origin" or the Hebrew rosh, which has a similar meaning. Early race theorists held the view that some races were inferior to others and they believed that the differential treatment of races was justified; these early theories guided pseudo-scientific research assumptions. Today, most biologists and sociologists reject a taxonomy of races in favor of more specific and/or empirically verifiable criteria, such as geography, ethnicity, or a history of endogamy.
To date, there is little evidence in human genome research which indicates that race can be defined in such a way as to be useful in determining a genetic classification of humans. An entry in the Oxford English Dictionary defines racialism as "n earlier term than racism, but now superseded by it", cites it in a 1902 quote; the revised Oxford English Dictionary cites the shortened term "racism" in a quote from the following year, 1903. It was first defined by the Oxford English Dictionary as "he theory that distinctive human characteristics and abilities are determined by race". By the end of World War II, racism had acquired the same supremacist connotations associated with racialism: racism now implied racial discrimination, racial supremacism, a harmful intent; as its history indicates, the popular use of the word racism is recent. The word came into widespread usage in the Western world in the 1930s, when it was used to describe the social and political ideology of Nazism, which saw "race" as a given political unit.
It is agreed that racism existed before the coinage of the word, but there is not a wide agreement on a single definition of what racism is and what it is not. Today, some scholars of racism prefer to use the concept in the plural racisms, in order to emphasize its many different forms that do not fall under a single definition, they argue that different forms of racism have characterized different historical periods and geographical areas. Garner summarizes different existing definitions of racism and identifies three common elements contained in those definitions of racism. First, a historical, hierarchical power relationship between groups. Though many countries around the globe have passed laws related to race and discrimination, the first significant international human rights instrument developed by the United Nations
CBC News, stylized as CBCnews, is the division of the Canadian Broadcasting Corporation responsible for the news gathering and production of news programs on the corporation's English-language operations, namely CBC Television, CBC Radio, CBC News Network, CBC.ca. Founded in 1941, CBC News is the largest news broadcaster in Canada and has local and national broadcasts and stations, it collaborates with its French-language counterpart, Radio-Canada Info, although the two are organizationally separate. The CBC follows the Journalistic Standards and Practices which provides the policy framework within which CBC journalism seeks to meet the expectations and obligations it faces from the public; the first CBC newscast was a bilingual radio report on November 2, 1936. The CBC News Service was inaugurated during World War II on January 1, 1941 when Dan McArthur, chief news editor, had Wells Ritchie prepare for the announcer Charles Jennings a national report at 8:00 pm. Readers who followed Jennings were Frank Herbert and Earl Cameron.
CBC News Roundup startet on August 16, 1943 at 7:45 pm, being replaced by The World at Six on October 31, 1966. On English-language television the first newscast, part of CBC Newsmagazine, was given on September 8, 1952 on CBLT, the only English station telecasting; that year CBC National News was introduced changing its name to The National in 1970. CBC began delivering news online in 1996 via the Newsworld Online website; the CBC News Online site launched in 1998. In 2009, CBC's Television News, Radio News and Digital News departments were merged into CBC News with a central assignment and reporting structure. In 2013, CBC News relaunched its CBC Aboriginal website, based in Winnipeg, with journalists in Toronto and other cities. In 2016, the site was renamed CBC Indigenous. In 2017, CBC News relaunched its flagship newscast, The National, with four co-anchors based in Toronto and Vancouver. CBC News has won Canadian awards including Michener, Canadian Screen, Canadian Association of Journalists and RTDNA awards and internationally, Prix Italia, Monte Carlo, Gabriel and International Emmys.
Thousands of hours of archival CBC News programming are available at the CBC Digital Archives Website and Facebook page. The Television News section of CBC News is responsible for the news programs on CBC Television and CBC News Network, including national news programs like The National, The Fifth Estate, The Investigators with Diana Swain and The Weekly with Wendy Mesley, they are responsible for news, business and sports information for Air Canada's inflight entertainment. The distinctive music on all CBC television news programs was introduced in 2006 as part of the extensive rebranding of all news programming under the CBC News title. Most local newscasts on CBC Television are branded as CBC News:, such as CBC News: Toronto at Six. Local radio newscasts are heard on the half-hour during morning and afternoon drive shows and on the hour at other times during the day; the Radio News section of CBC News produces on-the-hour updates for the CBC's national radio newscasts and provides content for regional updates.
Major radio programs include World Report, The World at Six, The World This Hour and The World this Weekend. The majority of news and information is aired on CBC Radio One. All newscasts are available via apps or via voice-activated virtual assistants. CBC News Online is the CBC's CBC.ca news website. Launched in 1996, it was named one of the most popular news websites in Canada in 2012; the website provides regional and international news coverage, investigative, business and entertainment. Investigative, business, Indigenous, health and tech news. An Opinion section was reintroduced in November 2016. Many reports are accompanied by podcasting and video from the CBC's television and radio news services. CBC News content is available on multiple platforms including Facebook, Instagram, etc. CBC News Network is an English-language news channel owned and operated by the CBC, it began broadcasting on July 31, 1989 from several regional studios in Halifax, Toronto and Calgary. It was revamped and relaunched as the CBC News Network in 2009 as part of a larger renewal of the CBC News division.
Current programs include CBC News Now, Power & Politics, The National with Adrienne Arsenault and, Ian Hanomansing, Andrew Chang and Rosemary Barton. In November 2005, the CBC News Weather Centre was established to cover local and international weather, using in part data provided by Environment Canada. Claire Martin was hired to serve as the primary face of the Weather Centre. In April 2014, the national Weather Centre was disbanded due to CBC budget cuts. In November 2014, citing difficulties implementing this new system, CBC announced a one-year trial content sharing partnership with The Weather Network, the owned cable specialty channel, which went into effect on December 8. Under the partnership, in exchange for access to weather-related news coverage from the CBC, The Weather Network provides the national weather reports seen on The National and CBCNN da
Sleep is a recurring state of mind and body, characterized by altered consciousness inhibited sensory activity, inhibition of nearly all voluntary muscles, reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than coma or disorders of consciousness, sleep displaying different and active brain patterns. Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. A well-known feature of sleep is the dream, an experience recounted in narrative form, which resembles waking life while in progress, but which can be distinguished as fantasy. During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous and muscular systems; the internal circadian clock promotes sleep daily at night. The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research.
Sleep is a conserved behavior across animal evolution. Humans may suffer from various sleep disorders, including dyssomnias such as insomnia, hypersomnia and sleep apnea; the advent of artificial light has altered sleep timing in industrialized countries. The most pronounced physiological changes in sleep occur in the brain; the brain uses less energy during sleep than it does when awake during non-REM sleep. In areas with reduced activity, the brain restores its supply of adenosine triphosphate, the molecule used for short-term storage and transport of energy. In quiet waking, the brain is responsible for 20% of the body's energy use, thus this reduction has a noticeable effect on overall energy consumption. Sleep increases the sensory threshold. In other words, sleeping persons perceive fewer stimuli, but can still respond to loud noises and other salient sensory events. During slow-wave sleep, humans secrete bursts of growth hormone. All sleep during the day, is associated with secretion of prolactin.
Key physiological methods for monitoring and measuring changes during sleep include electroencephalography of brain waves, electrooculography of eye movements, electromyography of skeletal muscle activity. Simultaneous collection of these measurements is called polysomnography, can be performed in a specialized sleep laboratory. Sleep researchers use simplified electrocardiography for cardiac activity and actigraphy for motor movements. Sleep is divided into two broad types: non-rapid eye movement sleep and rapid eye movement sleep. Non-REM and REM sleep are so different that physiologists identify them as distinct behavioral states. Non-REM sleep after a transitional period is called slow-wave sleep or deep sleep. During this phase, body temperature and heart rate fall, the brain uses less energy. REM sleep known as paradoxical sleep, represents a smaller portion of total sleep time, it is the main occasion for dreams, is associated with desynchronized and fast brain waves, eye movements, loss of muscle tone, suspension of homeostasis.
The sleep cycle of alternate NREM and REM sleep takes an average of 90 minutes, occurring 4–6 times in a good night's sleep. The American Academy of Sleep Medicine divides NREM into three stages: N1, N2, N3, the last of, called delta sleep or slow-wave sleep; the whole period proceeds in the order: N1 → N2 → N3 → N2 → REM. REM sleep occurs as a person returns to stage 1 from a deep sleep. There is a greater amount of deep sleep earlier in the night, while the proportion of REM sleep increases in the two cycles just before natural awakening. Awakening can mean the end of sleep, or a moment to survey the environment and readjust body position before falling back asleep. Sleepers awaken soon after the end of a REM phase or sometimes in the middle of REM. Internal circadian indicators, along with successful reduction of homeostatic sleep need bring about awakening and the end of the sleep cycle. Awakening involves heightened electrical activation in the brain, beginning with the thalamus and spreading throughout the cortex.
During a night's sleep, a small amount of time is spent in a waking state. As measured by electroencephalography, young females are awake for 0–1% of the larger sleeping period. In adults, wakefulness increases in cycles. One study found 3% awake time in the first ninety-minute sleep cycle, 8% in the second, 10% in the third, 12% in the fourth, 13–14% in the fifth. Most of this awake time occurred shortly. Today, many humans wake up with an alarm clock. Many sleep quite differently on workdays versus days off, a pattern which can lead to chronic circadian desynchronization. Many people look at television and other screens before going to bed, a factor which may exacerbate disruption of the circadian cycle. Scientific studies on sleep have shown that sleep stage at awakening is an important factor in amplifying sleep inertia. Sleep timing is controlled by the circadian clock, sleep-wake homeostasis, to some extent by individual will. Sleep timing depends on hormo