...(2007) 274 – 284 Altered sleep–wake cycles and physical performance in athletes Thomas Reilly ⁎, Ben Edwards Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, 15-21 Webster Street, Liverpool, L3 2ET, United Kingdom Received 14 August 2006; accepted 4 September 2006 Abstract 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...
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...a. Throughout sleep in an average brain, deep sleep is the first thing that we notice in the first half of the of the sleep cycle. After deep sleep occurs, we enter the second half of the sleep cycle and this is where REM sleep begins to occur. After about twenty minutes into stage four of the sleep cycle, you would begin to go back into the initial stages and then back into REM sleep. For abut every hour and a half, the sleep cycle would repeat through these stages. However, there are some changes that do occur. By the time you wake up, you would have spent around twenty-five percent of the night in REM sleep. The younger the person is, the more sleep they gain versus the elderly. Also, those who are younger tend to spend a lot of time resting...
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...advantages to this type of work there are negatives too, one of these is that there are major disruptions to the employee’s sleep patterns. Most sleep is needed during the times of 2-4 am. This is when most shift workers will struggle to get through their shift. Another reason why it affects them is because it changes the circadian rhythm. The circadian rhythm is a 24hour rhythm which a person recognises and it tells the person to sleep when it is dark and to wake when it is light. This is affected by shift work because they spend most their time under artificial light. Another reason why they struggle is because when the lights go off they need to make sure that they stay awake in case there us an emergency of some kind. Employees can sometimes be offered a night shift where they can have a couple of hours sleep, however they opt out of this type of contact because it pays less than what a night shift without sleeping does. Employers hardly ever give out these types of contract because they feel that they cannot justify paying employees to sleep whilst they are at work. Another biological rhythm that gets disrupted by shift work is the Ultradian Rhythm, this is a cycle that repeats more than once in a 24hour time period. The Ultradian rhythm describes the non-rem and the rem cycle. The non-rem cycle consist of 3 stages, however before the body enters into the rem cycle it has to go through all stages of...
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...hormone production, menstrual cycle and migration (among birds/animals), to name a few. All these functions follow a particular cyclical pattern. When this process recurs annually, it is known as a circannual rhythm. Similarly, when this process recurs on a daily basis, it is known as a circadian rhythm. The word circadian comes from the Latin words ‘circa diem’, meaning about a day. Circadian rhythms are controlled by a biological clock within our brain. This section of brain is called the 'suprachiasmatic nucleus' (SCN). Signals produced by the SCN travel to different sections of the brain, thus stimulating various functions, such as body temperature, hormone secretion, changes in blood pressure, etc. There are numerous external factors as well, that regulate a circadian rhythm among human beings. These external factors are called zeitgebers (Hawkins & Orlady, 1993). Most common zeitgebers are light and temperature. Others include meal times, various social and physical activities. The most common circadian rhythm known to mankind is the sleep cycle. Sleep is an extremely important physiological phenomenon, during which our body heals and recuperates. Let us begin with understanding what sleep is, and what are the various sleep patterns. Sleep is a revocable state, which is characterized by disconnection and unresponsiveness to the outside environment with closed eyes, reduced movements and recumbency (Smith, Comella, & Hogl, 2008). Normal sleep pattern is classified into...
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...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 and validity...
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...Chapter 2 REVIEW OF RELATED LITERATURE Related Literature Sleep is a fundamental part of life. It is not just a function of the body, it is an active process. Sleep is so vital to the body’s daily functioning that a prolonged loss of sleep impairs metabolism, immune function, temperature control and can ultimately lead to death (Rechtshaffen & Bergmann, 2002). As with other functions of the body, sleep cannot be localized to just one part of the brain. Its control mechanisms are entrenched at every level, starting with the cells. The same mechanisms that control autonomic functions, cognition, behavior, arousal and motor functions are all involved with the process of sleep. The 24-hour sleep/wake cycles, called circadian rhythms, developed as a response to the 24-hour astronomical cycle that all living things are exposed to (Pace-Schott & Hobson, 2002). The circadian system helpsthe body cycle through these phases. This system includes the retina, suprachiasmatic nuclei (SCN), the retinohypothalamic tract and the pineal gland. The suprachiasmatic nuclei is located in the hypothalamus, above the optic chiasm. It acts as a sort of clock, receiving photic information from the retina (via the retinohypothalamic tract) and regulating the timing and length of sleep (Kotagal & Pianosi, 2006). This “master clock” is so vital to the sleep-wake cycle that if the SCNs in hamsters with normal circadian rhythms are transplanted into those with abnormal rhythms, normal periodicity will...
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...thirty minutes of sleep and was expected to wake up at five am. During peoples' teenage years, they experience a change in their internal sleep clock. Teenagers should have their high school classes begin later in the day and end later in the day. High school starting later benefits the students in many ways. First, they will be wide awake in class and ready to learn....
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...Sigmund Freud revolutionized the study of dreams with his work The Interpretation Of Dreams. Freud developed several themes on dream psychology. He proposed the structure of the Human Psyche – the id, ego, and superego. Sigmund Freud was a world renowned psychologist and writer who forever changed the world of psychoanalysis. The three structures of the Human Psyche Freud proposed are: Id - centered around original impulses, pleasures, desires, and wish fulfillment. Ego - worried with the conscious, the sensible, the ethical and the self-aware aspect of the mind. Superego - the censor for the id, which is also responsible for enforcing the moral codes of the ego. (http://www.dreaminterpretation-dictionary.com/sigmund-freud-theory.html) First Freud believed that the Id directed our basic drive instincts. He said that it was unorganized and would seek to obtain pleasure or avoid pain. He described Id as chaos, a cauldron full of seething excitations, it is filled with energy reaching it from the instincts, but it has no organization, produces no collective will, but only motivation to bring out the satisfaction of instinctual needs. (http://www.dreaminterpretation-dictionary.com/sigmund-freud-theory.html) Next Freud thought of the Ego as the mediator, the egos job is to mediate the intropsychic conflict between the id and superego. The ego is the part of your personality that is responsible for dealing with reality, the ego strives to please the Id’s drive. ...
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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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...Powerful Sleep – Secrets of the Inner Sleep Clock by Kacper M. Postawski, PowerfulSleep.com Copyright © 2004 PowerfulSleep.com All 1 Rights Reserved Powerful Sleep – Secrets of the Inner Sleep Clock by Kacper M. Postawski, PowerfulSleep.com Table of Contents Disclaimer: ________________________________________________________________5 Introduction _______________________________________________________________6 The Popular Myth about Sleeping ________________________________________________ 6 Recent “Eye Opening” Discoveries ________________________________________________ 7 How Much Sleep Do You Really Need? ____________________________________________ 7 The Mystery of Quality Sleep ____________________________________________________ 7 Chapter 1: Sleep Mechanics __________________________________________________9 What is Sleep, and Why Do We Sleep? __________________________________________9 Your Crash Course on Brain Waves ______________________________________________ 9 The 5 Stages of Sleep ___________________________________________________________ 9 Sleep Cycles __________________________________________________________________ 11 How Important is Deep Sleep? __________________________________________________ 13 How Important is REM Sleep? __________________________________________________ 13 So what is Quality Sleep?_______________________________________________________ 14 Chapter 2: The Inner Sleep Clock_____________________________________________15 ...
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...Sleep and brain development: With the relevantly recent discovery of rapid eye movement (REM) sleep, the once subjective state of sleep is no longer expressed as a homogeneous occurrence of passive rest for the brain. Instead, REM sleep has, "appeared as an active condition of intense cerebral activity." (1). And to be even more interesting, the fact that as humans we get more sleep at younger ages, 25 and younger, when intense neurological development is taking place means that, "sleep may play a role in brain maturation." (1). A recent study has research sleep in young children as well as young adults. It has found that, "Sleep and sleep cycles begin at around 26 to 28 weeks' gestational age."(2) This means that patterns of REM and NREM have been found in infants, suggesting that there is some type of development taking place while in a sleeping state. The study goes on to show that, "Sleep and sleep cycles are essential for the development of the neurosensory and motor systems in the fetus and neonate. They are essential for the creation of memory and long-term memory circuits, and they are essential for the maintenance of brain plasticity over the lifetime of the individual." (2) Suggesting that sleep is essential for positive brain development for the rest of the life of that infant or young adults. It was also noted that any interference with sleep or sleep cycles can significantly hinder the early processes of sensory development. (2). It is clear that sleep is very...
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...The purpose of this paper is to evaluate the correlational method as a means for examining the relationship between REM sleep and memory. I will describe previous research and then investigate how REM and memory are associated in young people and in older people. In some ways, the sleep patterns of these two groups are very similar, but in some ways they are not. 1a. In the normal brain, REM sleep is the stage of sleep during which the body tends to be very relaxed, with little to no movement of the muscles. However, it is possible to observe occasional slight movements, called twitches, while one is in the REM stage of sleep. Despite the observable calmness of the body during this stage of sleep, heart and breathing rates increase during REM...
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...7: States of Consciousness CHAPTER PREVIEW Consciousness is our awareness of ourselves and our environment. Conscious information processing enables us to exercise control and to communicate our mental states to others. Beneath the surface, unconscious processing occurs simultaneously on many parallel tracks. Our daily schedule of waking and sleeping is governed by a biological clock known as circadian rhythm. Our sleep also follows a repeating cycle. Awakening people during REM sleep yields predictable “dreamlike” reports that are mostly of ordinary events. Freud’s view that dreams can be traced back to erotic wishes is giving way to newer theories, for example, that dreams help us process information and fix it in memory or that dreams erupt from neural activity. Studies of hypnosis indicate that, although hypnotic procedures may facilitate recall, the hypnotist’s beliefs frequently work their way into subjects’ recollections. Hypnosis can be at least temporarily therapeutic and has the potential of bringing significant pain relief. Hypnosis may be an extension both of normal principles of social influence and of everyday splits in consciousness. Psychoactive drugs also alter consciousness. Depressants act by depressing neural functioning. Although their effects are pleasurable, they impair memory and self-awareness and may have other physical consequences. Stimulants act at the synapses by influencing the brain’s neurotransmitters. Their effects depend on...
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...Brutlag BIOCHEM 158 Due April 08, 2013 Mendelian Disease Case Project 1. The genetic disease I have chosen is narcolepsy. The OMIM url can be found here: http://www.omim.org/entry/161400. 2. 1,2Narcolepsy is a neurologic sleep disorder characterized by excessive daytime drowsiness and the inability to properly regulate sleep cycles. Thus, narcoleptics experience REM sleep, the deepest stage of sleep when dreaming occurs, within five minutes of sleep onset. Narcoleptics may also experience cataplexy, sudden loss of muscle tone, when experiencing strong emotions including laughter, fear, excitement, etc. When waking up or during sleep onset, narcoleptics often experience sleep paralysis, a temporary state of complete loss of muscle control. Sleep paralysis occurs when the brain believes REM sleep is occurring even though one is already awake or just about to sleep so it is easy to see how narcoleptics who have trouble regulating sleep cycles also frequently experience sleep paralysis. Besides sleep paralysis, hallucinations are also common during waking up or sleep onset. For almost all cases, narcolepsy is caused by the lack of a brain neurotransmitter called hypocretin. The shortage then causes a shorter, improperly controlled sleep cycle. 3. Diagnosis of narcolepsy may seem simple enough because of its characteristic cataplexy symptom. However, while almost all cases of cataplexy are tied with narcolepsy, not all cases of narcolepsy are tired with cataplexy. In...
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...the relationship between REM sleep and memory. I will describe previous research and then research how REM and associated memory in young and older people. In a way, the sleep patterns of these two groups are very similar, but somehow are not. 1a For the adult brain changes sleep, REM sleep and slow wave to each other in cycles of about 90 minutes. Early in the evening, non-REM sleep is longer cycles, but as time passes, the REM cycles dominate. non-REM sleep involves minimal brain activity, EEG high amplitude and low frequency oscillations. REM sleep, on the other hand, involves a high amount of brain activity paradoxically and equally low amount of motor skills, with low amplitude and high frequency oscillations in the EEG. In the elderly, length and intensity of these cycles' occur in shorter periods. REM sleep occurs just and slow wave sleep occurs in shorter cycles. 1b REM sleep usually awakens the genitals in men and women. This effect is usually more deeply experienced in youth, with young men who have erection for a period of time that men and older. 1c When a person is awake and excited, high-frequency beta waves are observed. When a person is awake and relaxed, the low-frequency alpha waves are observed. In both REM and non-REM sleep-1, the waves are high frequency, low amplitude, and erratic. In non-REM-2 sleep, brain waves are a bit slower and less erratic, with brief bouts of high frequency brain activity. After REM-3 begins not sleep, the brain constantly emits high...
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