Psychology
Sleep Wake Cycle
The sleep-wake cycle, also known as the circadian rhythm, refers to the natural pattern of sleep and wakefulness that repeats roughly every 24 hours. It is regulated by the body's internal clock and influenced by external factors such as light and temperature. Disruptions to the sleep-wake cycle can lead to sleep disorders and impact overall health and well-being.
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10 Key excerpts on "Sleep Wake Cycle"
- John Weinman(Author)
- 2013(Publication Date)
- Butterworth-Heinemann(Publisher)
Finally, it should be noted again that although circadian variations in psychological processes can be demonstrated these do not necessarily have an absolute effect in that they can be modified by social, motivational and personality factors. • 4.3. Sleep The most obvious behavioural change which occurs during the circadian cycle is the transition from wakefulness to sleep. For most of us approximately one-third of the 24-hour period is spent in sleep and so a separate consideration of its nature seems appropriate. Moreover, sleep disorders are among the commonest symptoms seen by doctors and to some extent these can be understood more easily with reference to the 'normal' pattern of sleep. a. What is sleep? It is probably not too surprising to find that sleep occurs at a time in the circadian cycle when body temperature and arousal level are at their lowest. A common-sense interpretation of the functions of sleep would therefore be in terms of a recovery process in response to the activities of the preceding day and as a preparation for a new day. However, the notion of sleep as the natural response to a hard day's activity can be seen to be too limited since the amount of sleep may be relatively unaffected by the variability in waking levels of activity. It seems as if sleep constitutes a very basic part of the overall circadian pattern which is laid down in the early period of development and persists throughout life. One further misconception about sleep is that it is a somewhat passive state and corresponds to an absence of wakefulness and mental activity. It is now known that there are 47 Arousal, circadian rhythms and sleep brain regions which give rise to cortical rhythms associated with the onset and maintenance of sleep. Sleep is by its very nature a private event and relatively inaccessible to research investigation. In general terms, sleep is indicated by loss of awareness and a decreased responsiveness to the environment.
eBook - PDF- Jon C. Horvitz, Barry L. Jacobs(Authors)
- 2022(Publication Date)
- Cambridge University Press(Publisher)
Some genetic evi- dence suggests that these characteristics may run in families. 5.2 STAGES OF SLEEP 197 The study of circadian rhythms also helps us to understand jet lag. Say that your flight departs New York City at 8:00 p.m. and lands in Rome at 8:00 a.m. local time on the following day. In your excitement, you want to rush out immediately to see the Coliseum. However, it’s still only 2:00 a.m. in New York. With your sleep–wake cycle still entrained to New York zeitgebers, your biological clock tells you that you should be in bed. Expo- sure to the bright Roman morning sunshine will cause your internal clock to reset in a few days, i.e., your sleep–wake cycle will eventually entrain to the time cues in Rome. KEY CONCEPTS • Virtually all life on earth is influenced by a circadian cycle of approxi- mately 24 hours. • While typically influenced by external cues such as periods of light and darkness, a biological clock operates in the absence of any external signals. • In mammals, the brain mechanism controlling circadian rhythms is located in the suprachiasmatic nucleus of the hypothalamus. • The degree to which you feel tired depends on an interaction between your biological clock and how long you have been awake. TEST YOURSELF 1. If you were in a cave with no external cues about time of day, would you still show a circadian rhythm? Would you begin to sleep at random times during the day and night? 2. What brain structure is considered the brain’s master clock? 3. Sleep is said to be governed by circadian and homeostatic factors. Ex- plain what this means. 4. After a night without sleep, a person may be very tired at 4:00 a.m. Surprisingly, they may feel less tired at 9:00 a.m., even though they have had 5 additional hours without sleep! Why? 5.2 STAGES OF SLEEP In the sleep laboratory, researchers employ several physiological meas- ures as the individual sleeps. Three key measures are examination of brain waves, muscle activity, and eye movements.
eBook - ePubSleep Difficulties and Autism Spectrum Disorders
A Guide for Parents and Professionals
- Kenneth Aitken(Author)
- 2012(Publication Date)
- Jessica Kingsley Publishers(Publisher)
The similarities in the underpinning biological processes, across the animal kingdom, are allowing significant developments in our understanding of human sleep to be made through the study of its development in other ‘model organisms’ such as Drosophila melanogaster (the fruit fly) and Danio rerio (the zebrafish) (Hendricks, Sehgal and Pack 2000). In addition to sleep–wake cycle issues, mood disorders including unipolar depression and seasonal affective disorder are typically due to abnormalities of the circadian system (McClung 2007; Monteleone and Maj 2008). There is a growing body of evidence that circadian abnormalities are seen in a large proportion of individuals with ASDs (Glickman 2010). Methods for the reliable assessment of human circadian rhythms are now available and in use (see Hofstra and de Weerd 2008). Variations in cognitive ability follow a circadian pattern and are affected both by endogenous circadian clocks and external factors that vary the amount and timing of actual sleep (Kyriacou and Hastings 2010). W HAT IS SLEEP? A useful starting point in understanding and unravelling sleep problems is trying to get a basic idea of what sleep is, why we might do it and what it might be for. We should start by defining what we mean by sleep. There are many definitions to choose from. Here is a selection: Sleep is a reversible condition of reduced responsiveness usually associated with immobility. (Cirelli and Tononi 2008, p.1605) …sleep is that golden chain that ties health and our bodies together. (Thomas Dekker, The Gull’s Hornbook 1609) Sleep is the interest we have to pay on the capital which is called in at death; and the higher the rate of interest and the more regularly it is paid, the further the date of redemption is postponed. (Arthur Schopenhauer) Sleep that knits up the ravelled sleave of care, the death of each day’s life, sore labour’s bath, balm of hurt minds, great nature’s second course, chief nourisher in life’s feast
eBook - ePub- Irving B. Weiner, Randy J. Nelson, Sheri Mizumori(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
While all other relevant masking factors are held constant, sleep-wake cycles are scheduled to be either too long (28 hours) or too short (20 hours) to permit entrainment of the endogenous oscillator; under such conditions, the SCN oscillator free-runs with a period of approximately 24 hours, and the effects of the sleep-wake cycle on a given rhythm can be observed at all circadian phases. In the following section we highlight the distinct and combined influences of the sleep-wake cycle and the endogenous circadian clock on the expression of several biological rhythms—both behavioral and physiological—studied under conditions of constant routine and forced desynchrony. Normal Behavioral and Physiological Processes Modulated by Circadian Rhythmicity and Sleep-Wake Homeostasis: Performance, Mood, and Physiology Nathaniel Kleitman, a pioneer in sleep and circadian research, first made the systematic link between cognitive performance, chronobiology, and sleep in 1933 by noting a diurnal variation in speed and accuracy of cognitive performance. On a number of neurobehavioral tasks, he observed a consistent pattern of best performance in the afternoon and worst performance in the early in the morning, just after waking, and in the late evening, just before sleep (Kleitman, 1933). He also noted that this temporal variation in performance was directly related to the diurnal rhythm in body temperature. Since the concept of an endogenous circadian rhythm had not been considered in 1933, Kleitman assumed that by heating up the body, one could improve the speed and accuracy of brain function. Since that time, a number of studies have used constant routine protocols in an attempt to delineate the endogenous temporal variation of objective alertness and neurobehavioral performance
eBook - PDF- Thomas Brown(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Since we discussed the fe-male's rhythm in the last chapter, we will concentrate on circadian rhythms in this one. In the first section, we will explore the changes which occur in the normal individual across the 24 -hour cycle. Then we will examine the biological basis for this cycle, considering the evidence for the existence of an internal biological clock or oscillator. Do the circadian rhythms exist simply because the world turns at the rate of once per 24 hours? Or do we have a clock (or clocks) built into the nervous system which runs regardless of the social and visual cues associated with the day/night cycle? The last part of this section will examine what happens when the circadian rhythms are disrupted in various ways, and will lead us into discussions of jet lag and work shifts. The second section of this chapter will deal with sleep, an altered state of consciousness which is an integral part of the circadian rhythm. We will discuss the stages of sleep, and see how dreaming is a very unusual and puzzling kind of sleep. We will also discuss some sleep disorders, and what happens when a person is deprived of sleep for awhile. The deprivation studies can tell us something about why we sleep, and we will find that the intuitive answer, to rest, is proba-bly not the correct one. The third section of this chapter will deal with the brain mechanisms underlying sleep, dreaming, and waking. It is becoming the rule, rather than the exception, to find rhythmic ClTCddidYl vhvthtnS activity in physiological systems. Perhaps these rhythms were not as obvious before because it is necessary to take frequent measurements physiological changes across of some physiological variable over a period of several days to deter-the circadian cycle mine whether they show a circadian rhythm. As more data are col-lected, it is becoming clear that most systems do undergo daily, regular fluctuations.
eBook - ePub- D. S. Minors, J. M. Waterhouse(Authors)
- 2013(Publication Date)
- Butterworth-Heinemann(Publisher)
chapter 5Sleep and Wakefulness
Publisher Summary
This chapter provides an overview of the rhythm of sleep and wakefulness. This rhythm differs from others. If considered simply as awake or asleep, it is an alternation between two states and as such can be described mathematically by a rectangular wave rather than a cosine curve or indeed any other continuous function. Some of the properties of the sleep–wakefulness rhythm in humans differ from those of other rhythms. The relative importance of the exogenous and endogenous components of circadian rhythms has been assessed by investigating the extent to which the rhythms are affected by constant routines, time-zone shifts, days of abnormal length, and life in the absence of time cues. Not all these approaches can be used in studies of sleep–wakefulness rhythmicity for some reasons. The chapter highlights these reasons. Attempts to investigate the pattern of sleep and wakefulness have been made in two main directions. Indirect methods of assessing the rhythm have been used, and subjects deprived of all time cues or any rhythmic inputs have been studied. The sleep–wakefulness rhythm acts as a masking influence because it exerts a direct effect upon other rhythms, but whether or not it is an exogenous influence depends on the factors influencing the pattern of sleep and wakefulness.1 Studying the Sleep–Wakefulness Rhythm
The rhythm of sleep and wakefulness differs from those considered in previous chapters in two ways. First, if considered simply as ‘awake’ or ‘asleep’, it is an alternation between two states and as such can be described mathematically by a rectangular wave rather than a cosine curve (or indeed any other continuous function). Secondly, some of the properties of the sleep–wakefulness rhythm in man differ from those of other rhythms and so cannot be investigated by the same techniques as will now be discussed.
eBook - PDF- James Kalat(Author)
- 2018(Publication Date)
- Cengage Learning EMEA(Publisher)
Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 257 Module 8.1 Rhythms of Waking and Sleeping Endogenous Rhythms Setting and Resetting the Biological Clock Mechanisms of the Biological Clock In Closing: Sleep–Wake Cycles Module 8.2 Stages of Sleep and Brain Mechanisms Sleep and Other Interruptions of Consciousness The Stages of Sleep Paradoxical or REM Sleep Brain Mechanisms of Wakefulness, Arousal, and Sleep Brain Activity in REM Sleep Sleep Disorders In Closing: Stages of Sleep Module 8.3 Why Sleep? Why REM? Why Dreams? Functions of Sleep Functions of REM Sleep Biological Perspectives on Dreaming In Closing: Our Limited Self-Understanding Chapter 8 Wakefulness and Sleep Chapter Outline After studying this chapter, you should be able to: 1. Define and describe endogenous rhythms. 2. Explain the mechanisms that set and reset the biological clock. 3. List and characterize the stages of sleep. 4. Describe the brain mechanisms of waking and sleeping. 5. Discuss several consequences of thinking of sleep as a localized phenomenon. 6. List several sleep disorders with their causes. 7. Evaluate possible explanations of the func-tions of sleep. 8. Describe possible explanations of dreaming. Learning Objectives Opposite: Sleep is an important part of life for nearly all animals. (Hoberman Collection/Getty Images) A nyone deprived of sleep suffers. But if life evolved on another planet with different conditions, could animals evolve life without a need for sleep? Imagine a planet that doesn’t rotate on its axis.
eBook - PDFDiscovering Behavioral Neuroscience
An Introduction to Biological Psychology
- Laura Freberg(Author)
- 2018(Publication Date)
- Cengage Learning EMEA(Publisher)
INTERIM SUMMARY 11.1 Summary Points 1. Daily or circadian rhythms respond to both internal signals and external zeitgebers. Ultradian rhythms occur several times within a single day. (LO1) 2. The body’s internal master clock is the suprachiasmatic nucleus (SCN), which receives information about light via the retinohypothalamic pathway. (LO2) 3. Some biochemicals, such as melatonin,cortisol, and human growth hormone, show circadian patterns of activity. (LO2) ● Figure 11.10 Light Therapy Can Help Reset Circadian Rhythms Light therapy is available for free to travelers at Charles de Gaulle Airport in Paris, France. Although we don’t know for certain if this will reduce jet lag, light therapy is a standard treatment for major depressive disorder with seasonal pattern. Horizons WWP/TRVL/Alamy Stock Photo Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. CHAPTER 11 Sleep and Waking 388 Review Questions 1. How do shift work, jet lag, and daylight saving time affect our normal circadian rhythms? 2. What is the basis for the rhythmicity observed in the SCN? Neural Correlates of Waking and Sleep For many years, sleep was viewed as an absence of activity. Nothing could be further from the truth. Both waking and sleep are active processes that are carefully choreo-graphed by the brain. These states are not simply the results of activity in “waking” or “sleep” centers but, rather, involve reciprocal circuits of excitation and inhibition. For example, waking not only results from excitation in some parts of the brain but also requires the active inhibition of sleep.
eBook - ePubTeaching the World to Sleep
Psychological and Behavioural Assessment and Treatment Strategies for People with Sleeping Problems and Insomnia
- David R. Lee(Author)
- 2023(Publication Date)
- Routledge(Publisher)
There is a clock inside our brains, which operates continuously and without our conscious awareness, controlling a whole range of our physiological functions. This clock is not exclusive to humans, all animals and even plants have “rhythmicity”, periods of activity interspersed with regular periods of inactivity or quiescence. This rhythmicity was first noted as far back as 4BCE, but the first experimental evidence of their existence was conducted on plants in 1729 by a French scientist called Jean-Jacques d’Ortous de Mairan. Since then several periodicity genes have been identified, including: the CLOCK, PER1, PER2 and PER3 genes, simpler organisms have just one of these genes, more complex organisms have two, three, or all four of these genes, whose effect is to provide the host organism with this internal, or endogenous, clock. Humans have all three of the PER genes and the CLOCK gene and these are known to effect the suprachiasmatic nucleus (SCN) two distinctive groups of cells at the back of the hypothalamus in the centre of our brains. Circadian technically means around a day, and our Sleep Wake Cycle follows this circadian, or 24 hour rhythm. The endogenous rhythm generated by the SCN is actually an ultradian rhythm (meaning less than a day) and it is these ultradian rhythms which are so important for our sleep. Adults have an ultradian rhythm of ninety minutes, and this is very regular. Even in people in the advanced stages of dementia, this endogenous rhythm clicks along continuously and many of our functions are controlled and influenced by it. The cycling of REM and non-REM sleep follow this rhythm. Hunger and thirst, urine production, alertness, even creativity follow this rhythm, along with many other functions. Here are a couple of practical examples that help to explain the phenomenon: We are all familiar with a dip in alertness mid-afternoon, and another before we go to bed, at these times our ultradian rhythm is reaching a minimum, our alertness is at its lowest, and it is here when we can easily initiate sleep. If we wait half an hour though, our alertness is on the rise and we begin to reach a peak, this is when sleep is very difficult to initiate. If you have ever shifted your bedtime from its normal time, then it is often difficult to get sleep. For example: “I’ll be getting up early tomorrow to catch an early flight, so I’d better go to bed early,” and then you cannot get off to sleep until the usual time. Or, you go to bed later than usual and think: “Why can’t I sleep, it’s past my usual bedtime, I should be tired and so I should be able to get to sleep”. If you want to shift your bedtime from its usual slot then you need to move it by ninety minutes to catch the preceding, or succeeding, ultradian dip. This can be hugely effective in the therapeutic intervention for insomnia, and we will return to this later in Chapters Five and Six on the treatment of sleeping problems.
eBook - PDF- George Spilich(Author)
- 2023(Publication Date)
- Wiley(Publisher)
338 CHAPTER OUTLINE 13.1 The Mystery of Sleep • Evolutionary Patterns of Sleep Think About It: Has Civilization Changed How We Sleep? • The Purpose of Sleep 13.2 Sleep Stages and Dreaming • The Study of Sleep • The Stages of Sleep Try It Out: What’s Your Sleep IQ? • Dreaming Try It Out: Are You a Lucid Dreamer? 13.3 The Biological Basis of Sleep • Sensory Stimulation and Sleep • The Reticular Activating System and Sleep • The Brainstem, Hypothalamus, and Sleep • Neurotransmitters and Sleep Advances in Behavioral Neuroscience: Gina Poe and the Role of Sleep in Memory 13.4 Sleep Disruptions • Drugs and Sleep • Sleep Disorders Think About It: Sleep Insufficiency 13.5 Circadian Rhythms • Melatonin and the Sleep–Wake Cycle • The Suprachiasmatic Nucleus • When Diurnal and Circadian Rhythms Are Mismatched Try It Out: The Dangers of Microsleep LEARNING OBJECTIVES LO 13.1 Describe sleep, its evolution, and its purpose. LO 13.2 Describe the stages of sleep and their functions, including dreaming. LO 13.3 Identify the brain mechanisms that create sleep. LO 13.4 Describe common sleep disorders. LO 13.5 Relate circadian rhythms to the larger phenomenon of sleep. CHAPTER 13 Sleep, Dreaming, and Circadian Rhythms Sleep is essential for life. When we cannot sleep, the consequences are serious. Shine Nucha / Shutterstock 13.1 The Mystery of Sleep 339 Stories of the Brain On a crisp and clear December morning in 2013, a commuter train was approaching its even- tual destination in New York City. The train carried people on their way to work, shop, visit museums, and sight-see. The scenery flew by in a blur as the train was moving at a rapid pace. As the train neared its destination, it entered a rather sharp curve near the Henry Hudson Bridge in the Bronx, and a few of the regular passengers who were familiar with the route looked up from their newspapers when they realized the train was not slowing down as it usually did.
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