...Circadian Rhythms and Shift Working The concept of circadian rhythms can be a complex matter, however, understanding the basic purpose is quite simple. Associated with all living creatures, from bacteria and insects to plants and animals, circadian rhythms are like metaphorical clocks within an organism's control center (brain) that are responsible for regulating biological functions including wakefulness, sleep, appetite, and temperature. These physiological aspects are absolutely necessary for a healthy life cycle, therefore, ensuring that these cells that control circadian rhythms are properly functioning is crucial to health. Maintaining a balanced lifestyle where we receive an adequate amount of physical activity and sleep as well as nutrients is something that many individuals are aware of, though, when we lead busy lives that disrupt our sleep or appetite patterns, circadian rhythms can become poorly affected and/or altered by negative impacts from daily activities. Shift work, for instance, can often be stressful on our circadian rhythms, which can later lead to avoidable illnesses and diseases. The purpose of this paper is to discuss the basis of circadian rhythms as well as how certain physiological processes can be affected by shift work. Circadian rhythms are regular fluctuations that occur in parts of the body, depending on physiological function; these fluctuations go from high to low points within a twenty-four hour time frame ("Circadian rhythm", n.d.). These...
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...Describe and evaluate research into circadian rhythms (8+16) Research into circadian rhythms has assessed the effects of isolating participants from external time cues (exogenous zeitgebers) on our 24 hour cycles, and suggesting that an internal body clock (endogenous pacemaker) creates a free running sleep/wake cycle rhythm of 25 hours. Siffre (1975) * Case study of his own experiences in an underground cave for 2 months. Without any exogenous zeitgebers such as light or cues to guide him, his sleep/wake cycle generally adjusted to a 25 hour cycle, though sometimes changing dramatically up to 48 hours. Aschoff and Weaver (1976) * Designed a temporal isolation study by placing participants in an underground ww2 bunker without an environmental or time cues. * They found that the free running cycle persisted with a sleep wake cycle of 25 hours, sometimes increasing to 29. Weakness into research of circadian rhythms * Lack internal validity. * They removed natural light sources, artificial light from torches and cameras have been shown to reset the endogenous rhythms, thus interfering as an extraneous variable. Exemplified through Czeisler et al (1999) * Altered participants’ circadian rhythms down to 22 hours and up to 28 only using dim lighting to alter his release of melatonin from the pineal gland. * Findings do not reflect true isolation and have lower internal validity, so his rhythm may not have adjusted so well if he had been truly...
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...the control of one or more circadian rhythms (8 + 16 marks) Endogenous pacemakers are the internal biological clocks that manage our rhythms. In humans, the main biological clock is the suprachiasmatic nucleus also referred to as the SCN which is a small cluster of neurons located in the hypothalamus in the brain. This is what controls circadian rhythms of sleep- waking, body temperature and feeding patterns, the SNC is located above the optic chiasm therefore when light hits the retina it transfers through the optic nerve to the SCN which stimulates the release of hormones such as cortisol and melatonin in the pineal gland, maintaining our sleep- wake cycle. It’s been suggested from a evolutionary psychologists that endogenous pacemakers have an adaptive value in controlling biological rhythms such as the sleep- wake cycle, therefore suggesting it aids survival. This idea is supported by studies from psychologists such as Decoursey who found that removing the SCN in 30 chipmunks and returning them to their natural habitat, proved costly for their survival. They found that after 80 days significantly more chipmunks had died compared to control group with normal functioning SCN’s. Therefore, this suggests that EP, most importantly the SCN, indeed aids survival, as the absence of this important EP proved detrimental for the survival of the chipmunks. Moreover, another study that supports this idea is the study of free running biological rhythms by Michel Siffre. This was...
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...Audience hook: Large portions of the population are affected by mood disorders. These mood disorders seem to be directly related to significant disruptions of both the circadian rhythm and the sleep/wake cycle (McClung, 2012). b. Thesis Statement: Research suggests the circadian rhythm is influenced by sunlight and regulates our mood. c. Preview of Main points: i. The circadian rhythm ii. The correlation between sunlight and mood swings. II. The location and function of the circadian rhythm. (See visual aids attached) a. The circadian rhythm is the name of the internal body clock of living organisms. i. The internal body clock helps the body to adapt to the daily cycle of day and night. ii. The daily cycles involve “clock gens” which control the cycles in rhythmic waves. iii. Location of the master circadian is in the hypothalamus iv. Light is transmitted to the master circadian through the retina of the eye. v. The registration of light isn’t through conscious vision, but through rods and cones in the retina (Borvin, 2013) III. The correlation between (sun) light and mood swings. a. The hormone melatonin is used as the circadian marker. It is produced during the night and under absolute condition of darkness b. Inadequate light will disrupt the circadian rhythm and cause change in the release of hormone controlling brain activity. c. Change in melatonin release can cause sleep deprivation. Lack of sleep causes mood swings...
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...Institute Circadian rhythms are regular changes in mental and physical characteristics that occur in the course of a day (circadian is Latin for "around a day"). Most circadian rhythms are controlled by the body's biological "clock." This clock, called the suprachiasmatic nucleus or SCN, a pair of pinhead-sized brain structures that together contain about 20,000 neurons. The SCN rests in a part of the brain called the hypothalamus, just above the point where the optic nerves cross. Light that reaches photoreceptors in the retina (tissue at the back of the eye) creates signals that travel along the optic nerve to the SCN. Signals from the SCN travel to several brain regions, including the pineal gland, which responds to light-induced signals by switching off production of the hormone melatonin. The body's level of melatonin normally increases after darkness falls, making people feel drowsy. The SCN is synchronized with the sleep/wake cycle, including body temperature, hormone secretion, urine production, and changes in blood pressure. Sunlight or other bright lights can reset the SCN, our biological cycles normally follow the 24-hour cycle of the sun, rather than our innate cycle. Circadian rhythms can be affected to some degree by almost any kind of external time cue, such as the beeping of your alarm clock, the clatter of a garbage truck, or the timing of your meals. Scientists call external time cues zeitgebers (German for "time givers"). Circadian rhythms is the sleep/wake...
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...Class: BBA-8 Circadian Rhythms as a basis of mood disorder, in particular bipolar disorder. Introduction: The complex structure and the functions of the human body has been a subject of study by a lot of individuals since a very long time. The curiosity of the human being supporting it, further aids in discovering the secrets hidden behind the way a human being is. Biological rhythms or circadian rhythms also make up one of the hidden secrets for the functions of the human beings and scheduling of various tasks. The terms Circadian is derived from Latin word Circa, “around” or “about” and diem or dies “day” meaning literally “about a day” or “around a day”. This circadian rhythm is already built in the complex human body but is regulated by external factors known as “zeitgebers”. The primary or the most important zeitgebers is ‘light’ which helps human automatically start a particular process in one’s life and controls various cycles at regular intervals. This may include sleep/wake cycle, eating habits, seasonal affective disorder (SAD) or bipolar disorder. Scientists have long been researching the effects of disturbance of circadian rhythms and its consequences on the life of a human being. This paper also considers the facts that have been established in this area to identify and discuss the process undergoing in a human being and its complexities with a particular reference to circadian rhythms and bipolar disorder, its causes and how...
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...Endogenous pacemakers A study done on rats by Stephan et all where they damaged the SCN cells by removing them to see the effect it had on circadian rhythms. They put one group in 12 hours of light and the other in 12 hours of darkness. They found the rats with no SCN drank more and were more active in light than darkness. They concluded that if the SCN is damaged the circadian rhythm goes. A study that also supports this is the study done by Morgan who used hamsters but they transplanted SCN cells from mutant hamsters, which followed a 20-hour cycle into a hamster with a normal 24 hour cycle. They found that the normal hamster took on the 20-hour cycle. This is backed up by anatomical studies which have shown the presence of the SCN just above the optic nerve which is part of the eyes and we know that the eyes play a big part in the sleep wake cycle and are effected by light. The non-human animal studies are supported by brain tumours that have damaged the SCN have caused messed up circadian rhythms. This shows that SCN has the effect on both types of animals this means the studies results can be applied to human and non-human animals. However both studies done on animals were very unethical as the procedures used to damage or remove the SCN cells caused death and permanent damage to the animals causing them physical damage, which is not reversible. However the scientific methodology is good as it was done in a lab so it is very scientific, all variables are controlled and...
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...I. Introduction The first time you will hear the word Circadian Rhythm, you will be dreary because you have no idea on what it is about, but because of my drastic intention I will gather more ideas about my topic. Doubtless, I am sure I will make it easier to work with it. One question was bothering me and makes me persevere on doing this Research Paper. “Is it entrainable or not?”, one question with different ideas and information’s sticking with it. No specific and particular reviews I need to provide about it, I just need to gather information by means of researching just to know if Circadian Rhythm is entrainable or not. Although the process is not easy, as people who have suffered from a jetlag, because the more time you did not sleep, the more you will suffer Circadian Rhythm. Sleep and waking, for instance, occur naturally to the beat of an internal pacemaker, which works on a cycle of about twenty-four-hours. My purpose on making and researching is to have broad ideas and I need to answer the question bothering me if it is entrainale or not. I need to defend my title against myself to be proudly to present it and defend it easily.In my title, I used the questioning type because I want to know if Circadian Rhythm is truly entrainable or not. Y abstract focuses on the summary of my entire research paper and what are my goals and objectives on making this research. In listing the methods and procedures, my goal is to give the reader sufficient...
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...The Clocks Within Us Analysis According to the article published in the February 2015 edition of the Scientific American, genes in the brain, liver, pancreas, and other tissues help keep the various parts of the body in sync. These ideas are portrayed throughout the article written by Keith C. Summa and Fred W. Turek, “The Clocks Within Us.” The article is based around circadian rhythms, which describes how the body works around 24-hour cycles. Both authors are extremely validated when it comes to informing the public on circadian rhythms. Summa is a PhD at the Northwestern University Feinberg School of Medicine and is interested in understanding how to apply research findings to clinical medicine. Turek is a neurobiologist and director of the Center for Sleep and Circadian Biology at Northwestern. He is also the founding president of the Society for Research on Biological Rhythms. Learning more about the different clocks in the body can help explain bodily disruptions caused by out of sync cellular clocks. Circadian rhythms are important in the world of biology because of their effects on one’s health. When all the clocks in our body are not in sync, we can experience diabetes, depression, obesity, and more. The clocks could fall out of sync when sleep and eating patterns falter. This information could have been presented in the Scientific American, a popular magazine that is read by many people across the nation, because many people change their daily patterns. For example...
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...Nye, SN Our Lady of Lourdes School of Nursing The Impaired Nurse: Sleep Deprivation The impaired nurse is a major subject matter in evidence based research. Healthcare services are available twenty four hours a day, three hundred-sixty five days a year. With that being stated, shift work is a requirement in the healthcare field. Sleep deprivation is the lack of sleep due to an external stimulus preventing the opportunity of sleeping and this is a commonly known result of shift work in nurses. Sleep disorders commonly occur with nurses who work rotating shifts. Sleep quality is important, but sleep is not just about how many hours you get. Night shift workers have to sleep during the day which may interfere with their body’s rhythm telling them it is daytime and this jeopardizes their sleeping. This is where sleep deprivation comes into play. Shift work is a major source of disturbances in the healthcare profession. Most healthcare employees have no say over which shift they work. Chan (2008) studied this by using subjective measurements. The Karolinska Sleep Questionnaire was used to address nurses’ sleep patterns. Chan (2008) found that sleep deprivation causes symptoms such as arousals, exacerbations of gastrointestinal problems, and lowers threshold. This is because the stress system is activated by this sleep situation and neuro-hormonal stress act in response and alters the immune system, which then effects the cognitive and limbic systems (Chan, 2008)...
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...Circadian rhythms essay plan. Introduction AO1 Circadian rhythms are biological cycles that last around 24 hours There is a free running cycle controlled by an endogenous pacemaker working as a body clock which is internal to our biological system, such as the suprachiasmatic nucleus which receives information about light and dark directly from the retina of the eye and the pineal gland, which releases melatonin in relation to fading light. Melatonin acts upon the raphe nuclei which in turns produces serotonin, a chemical with an inhibitory or slowing down effect on the central nervous system. Also, circadian rhythms can be controlled by exogenous zeitgebers i.e. external time givers, such as light, temperature and social cues. Another circadian rhythm is body temperature, which is at its lowest at around 4.30 am. The core body temperature also lowers after lunch. Evaluation AO2 Siffre (1962)- He spent two months in an underground cave, without time cues and emerged on the 27th of September, but he thought it was the 20th of August. This suggests that the absence of exogenous zeitgebers, affected his perception of time, therefore giving evidence that endogenous pacemakers control our circadian rhythms. He then carried out further research to see if the absence of exogenous zeitgebers would affect his sleep- wake cycle. He spent six months in a cave, with no time cues, but artificial lights. He settled into a sleep wake cycle of around 25 hours. This therefore gives reliability...
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...The Consequences of Disrupting Biological Rhythms All living organisms experience rhythmic changes, which tend to coincide with seasonal or daily environmental changes. These rhythms are known as biological rhythms, which include circadian, ultradian and infradian types. All biological rhythms are controlled by two different factors - internally (endogenous) through nature, and externally (exogenous) through nurture. Most organisms have internal biological clocks, called endogenous pacemakers. The main endogenous pacemaker in circadian rhythms is the suprachiasmatic nucleus (SCN), a small bundle of nerves in the hypothalamus, as suggested by Morgan (1995), and Kalat (1998). Kalat suggested that low levels of light lead to an electrical stimulant, which activates the pineal gland in the SCN, located in the centre of the brain, to secrete a hormone called melatonin, which causes sleepiness. Its production of melatonin varies with periods of light and darkness in the environment, and it obtains this information about light in the environment by means of nerve pathways originating in the eyes. Therefore the main exogenous zeitgeber ('time-giver') that controls circadian rhythms is therefore light. Research that suggests the SCN is the main endogenous factor for circadian rhythms comes from Morgan in 1995. His aim was to determine whether the SCN in hamsters is linked to the dissappearance of their circadian rhythms. He removed the SCN from hamsters and transplanted an...
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...long complained, it's not that they're lazy, it's just that parents and schoolteachers don't understand them. Now they have been given top-grade academic ammunition to hurl at annoying adults before slamming the bedroom door and going back to bed - lying in bed for hours at the weekend is part of their inborn cycle of sleep and wakefulness. It's circadian rhythms innit. A US study published today in the journal Paediatrics found that early school starts were forcing students to perform academically at a time of day when they were at their worst. The researchers, from Northwestern University in Illinois, go so far as to describe the school day as causing an "epidemic of sleep deprivation among adolescents". They say the weekend lie-in enjoyed by so many young people is simply part of their natural cycle and should not be dismissed as laziness. Sixty students at Evanston Township high school in Illinois kept sleep diaries during school holidays and term-time as part of the study. Bright light was "administered" in the morning (presumably by flinging open the curtains?) in an attempt to normalise the timing of the circadian cycle. This made no difference at all. They showed that adolescents lost as much as two hours of sleep per night during their first week back at school week after the summer holiday and made up at weekends by sleeping longer. All the students performed better in class during the afternoon than in the morning, observed the researchers who gave...
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...Sleeping, like eating, breathing, and staying hydrated, is a crucial element of human life, though it isn’t always treated as such. Getting a good night’s rest is especially necessary during the teenage years, as many hormones that stimulate growth and development are released only while the body is dormant (Pietrangelo). Teenagers require, on average, 9 and ¼ hours of sleep each day (Later School Start Times). At the same time, their natural circadian rhythms trigger sleepiness later at night (Later School Start Times). Thus, while many teenagers are unable to fall asleep before, or even at, 11 PM, they are still forced out of bed at the crack of dawn and expected to be alert and ready to learn within an hour of doing so (Later School Start Times). This pattern creates a harmful sleep deficit, wreaking havoc...
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...Sleep–waking cycles are fundamental in human circadian rhythms and their disruption can have consequences for behaviour and performance. Such disturbances occur due to domestic or occupational schedules that do not permit normal sleep quotas, rapid travel across multiple meridians and extreme athletic and recreational endeavours where sleep is restricted or totally deprived. There are methodological issues in quantifying the physiological and performance consequences of alterations in the sleep–wake cycle if the effects on circadian rhythms are to be separated from the fatigue process. Individual requirements for sleep show large variations but chronic reduction in sleep can lead to immuno-suppression. There are still unanswered questions about the sleep needs of athletes, the role of ‘power naps’ and the potential for exercise in improving the quality of sleep. © 2006 Elsevier Inc. All rights reserved. Keywords: Circadian rhythm; Exercise; Jet-lag; Shift-work 1. Introduction The sleep–wakefulness cycle is the most discernable of human circadian functions, activity being associated with the hours of daylight and sleep with the hours of darkness. This recurrence on a daily basis is linked with responses of the pineal gland to the environment, its secretion of melatonin being promoted at dusk and inhibited on exposure to morning light. There is a myriad of other biological functions that are knit into a common system of circadian rhythms, cycles in behaviour and in biological functions...
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