sleep by pengxuebo

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									Role of Conscious and
Biorhythms in Organism’s Activity
      Consciousness and its
          mechanisms
• Consciousness is special form of perceiving
  surroundings and goal-orientated activity of person with
  interrelation to surroundings. Only social life forms
  consciousness. It involves life experience of entire
  society.
• This ability of prefrontal areas to keep track of many
  bits of information could well explain abilities to
  prognosticate, do plan for the future, delay action in
  response to incoming sensory signals, consider the
  consequences of motor actions even before they are
  performed, solve complicated mathematical, legal, or
  philosophical problems, correlate all avenues of
  information in diagnosing rare diseases and control our
  activities in accord with moral laws.
    The process of sensation and
       perceptual conclusions
• The process of sensation results in the transmission of
  neural messages to the brain, where the psychological
  process of perception occurs.We actively construct
  perceptual conclusions about this sensory information.
• In arriving at those perceptual conclusions, we are
  guided by well-established perceptual principles, such as
  the cues that typically indicate distance, movement,
  form, and so forth.
• But our perceptual conclusions can also be influenced by
  a variety of psychological factors, including our
  expectations, learning experiences, and experiences that
  are unique to our culture.
The nativist position and empiricist
              position
• The Gestalt psychologists believed that
  perceptual processes are inborn, a viewpoint
  called the nativist position. According to this
  position, people everywhere, whatever their
  background, see the world in the same way
  because they share the same perceptual rules.
• Other psychologists have advocated the
  empiricist position, believing that people actively
  construct their perceptions by drawing on their
  prior learning experiences, including cultural
  experiences.
Muller-Lyer llusion
                   • The Gestalt principles of
                     perceptual organization
                     contribute to the illusion of
Visual illusions     triangular contours of this
                     image. In organizing these
                     visual fragments, which are
                     lined up very precisely, the
                     Gestalt principles of closure
                     and good continuation
                     contribute to the perceptual
                     construction of a solid white
                     triangle covering three black
                     disks and an inverted
                     triangle. An intriguing
                     second illusion is also
                     occurring: The pure white
                     illusory triangle seems
                     brighter than the
                     surrounding white paper.
        Consciousness studying
• Wilhelm Wundt’s investigations of consciousness, begun in
  1879, were central to the development of psychology as a
  field of study. Wundt’s approach, called structuralism, sought
  to determine the structure of consciousness by recording the
  verbal descriptions provided by laboratory subjects to various
  stimuli, a method that became known as introspection.
• The next major approach to the study of consciousness was
  the functionalism of William James, who focused on how
  consciousness helps people adapt to their environment.
  Behaviorism, pioneered by John B. Watson in the early
  1900s, shifted interest from conscious processes to
  observable behaviors, and the study of consciousness faded
  into the background for almost half a century, especially in the
  United States, until it was revived by the “cognitive revolution”
  that began in the 1950s and 1960s.
              Consciousness:
           Sigmund Freud’s model
• The existence of different levels of consciousness was at the heart
  of Sigmund Freud’s model of human mental functioning.
• In addition to the conscious level, consisting of thoughts and feelings
  of which one is aware, Freud proposed the existence of the
  unconscious, a repository for thoughts and feelings that are
  repressed because they are painful or unacceptable to the
  conscious mind for some other reason.
• He also formulated the concept of the preconscious, which
  functions as an intermediate or transitional level of mind between
  the unconscious and the conscious.
• A preconscious thought can quickly become conscious by receiving
  attention, and a conscious thought can slip into the
  preconsciouswhen attention is withdrawn from it. In contrast, the
  repressed material contained in the unconscious can only be
  retrieved through some special technique, such as hypnosis or
  dream interpretation. (What Freud called the unconscious is today
  referred to by many psychologists as the subconscious.)
Consciousness: Carl Jung’s model
• Freud’s contemporary, Carl Jung, posited the
  existence of a collective unconscious shared by
  all people which gathers together the
  experiences of previous generations.
• The collective unconscious contains images and
  symbols, called archetypes, that Jung found are
  shared by people of diverse cultures and tend to
  emerge in dreams, myths, and other forms.
• In Jung’s view, a thorough analysis of both the
  personal and collective unconscious was
  necessary to fully understand the individual
  personality.
           Circadian rhythms
• In response to morning light, signals from
  photoreceptors in the eye are relayed via the
  optic nerve to the suprachiasmatic nucleus. In
  turn, the suprachiasmatic nucleus causes the
  pineal gland to reduce the production of
  melatonin, a hormone that causes sleepiness.
• As blood levels of melatonin decrease, mental
  alertness increases. Daily exposure to bright
  light, especially sunlight, helps keep the body’s
  circadian rhythms synchronized and operating
  on a 24-hour schedule.
Circadian Temperature Rhythm
           The Biological Clock
• A tiny sliver of brain tissue, less than the size of a
  pinhead, regulates the timing of our bodies. Within this
  sliver lies a biological clock that keeps track of the time
  of day, and seasons of the year, and marches our bodies
  and brains in step.
• The small cluster of nerve cells that forms the biological
  clock is called the suprachiasmatic nucleus (SCN). Its
  name derives from the location of the SCN, just above
  where the broad optic nerve trunks cross over each
  other (a site known as the "optic chiasm") on their way
  back from the eyes to the visual center of the brain.
• The SCN also receives information about light and dark
  from the eyes, but it has its own dedicated pathway of
  nerves, the retino-hypothalamic tract (RHT), which is
  separate from the main nerve bundles carrying visual
  information to the brain.
          The Biological Clock
• We know that the SCN is a biological clock because
  when it is destroyed in an experimental animal by
  surgical pinpoint lesions of the brain, rhythms in sleep
  and wake, and many other rhythms, fade away.
  Interestingly, the animal, minus its SCN, runs, eats and
  drinks the same total amount each 24 hours, but these
  activities are now randomly distributed throughout the
  day and night.
• One final fact about human biological clocks -- they
  actually follow a pattern of about 25 hours. Hence, if
  someone lives in a cave or an apartment without
  windows (as people have done), their circadian patterns
  of sleep and wakefulness shift "westward" by about one
  hour a day. However, in the regular world, sunlight and
  darkness serve to "reset" the biological clock every day
  and keep us on a 24-hour cycle.
      Suprachiasmatic nucleus
• Circadian rhythms are controlled by a master biological
  clock-a tiny cluster of neurons in the hypothalamus in the
  brain. This cluster of neurons is called the
  suprachiasmatic nucleus.
• The SCN is the internal pacemaker that governs the
  timing of circadian rhythms, including the sleep-wake
  cycle and the mental alertness cycle.
• Keeping the circadian rhythms synchronized with one
  another and on a 24-hour schedule also involves
  environmental time cues. The most important of these
  cues is bright light, especially sunlight.
• Normally the sleep-wake cycle, body temperature, and
  the melatonin cycle are closely coordinated.
Suprachiasmatic Nucleus (SCN)
               Role of melatonin
• The decrease in available light is detected by the SCN through
  its connections with the visual system. In turn, the SCN
  triggers an increase in the production of a hormone called
  melatonin.
• Melatonin is manufactured by the pineal gland, an endocrine
  gland located in the brain. Increased blood levels of melatonin
  make a person sleepy and reduce activity levels.
• At night, blood levels of melatonin rise, peaking between 1:00
  and 3:00 A.M. Shortly before sunrise, the pineal gland all but
  stops producing melatonin, and a person soon wakes up.
• As the sun rises, exposure to sunlight and other bright light
  suppresses melatonin levels, and they remain very low
  throughout the day. In this way, sunlight entrains, or sets, the
  SCN so that it keeps circadian cycles synchronized and
  operating on a 24-hour schedule.
                    Sleep
• People experience not only different levels, but
  also different states of consciousness, ranging
  from wakefulness (which may be either active or
  passive) to deep sleep. Although sleep
  suspends the voluntary exercise of both bodily
  functions and consciousness, it is a much more
  active state than was once thought.
• Tracking brain waves with the aid of
  lectroencephalograms (EEGs), researchers
  have identified six stages of sleep (including a
  pre-sleep stage), each characterized by
  distinctive brainwave frequencies.
                Theories of sleep
• Two theories of sleep, the repair and the adaptive theories,
  attempt to explain why sleep occurs.
• In the repair theory, sleep serves a biological need, replenishing
  key areas of the brain or body which are depleted during the
  day.
• The adaptive theory suggests that sleep as a function evolved
  over time because it prevented early humans from wasting
  energy and exposing themselves to nocturnal predators, thus
  aiding in survival.
• REM sleep in particular has been thought to serve special
  functions. Research subjects whose REM sleep was interrupted
  made up for the loss by spending extra time in the REM stage
  on successive nights. It has also been suggested that REM
  sleep aids the activity of neurons that use the neurotransmitter
  norepinephrine, thus maintaining waking alertness. Persons
  deprived of REM sleep have shown poorer retention of skills
  learned during the day, leading to the hypothesis that REM
  sleep helps in assimilating daytime learning experiences.
               Stage 1 NREM
• As the alpha brain waves of drowsiness are replaced by
  even slower theta brain waves, you enter the first stage
  of sleep. Lasting only a few minutes, stage 1 is a
  transitional stage during which you gradually disengage
  from the sensations of the surrounding world.
• Familiar sounds, such as the hum of the refrigerator or
  the sound of traffic, gradually fade from conscious
  awareness. During stage 1 NREM, you can quickly
  regain conscious alertness if needed. Although
  hypnagogic experiences can occur in stage 1, less vivid
  mental imagery is common.
• Although dreamlike, these images lack the unfolding,
  sometimes bizarre details of a true dream.
                Stage 2 NREM
• Stage 2 represents the onset of true sleep.
• Stage 2 sleep is defined by the appearance of sleep
  spindles, brief bursts of brain activity that last a second
  or two, and K complexes, single but large high-voltage
  spikes of brain activity that periodically occur. Other than
  these occasional sleep spindles, brain activity continues
  to slow down considerably.
• Breathing becomes rhythmical. Slight muscle twitches
  may occur. Theta waves are predominant in stage 2, but
  large, slow brain waves, called delta brain waves, also
  begin to emerge.
• During the 15 to 20 minutes initially spent in stage 2,
  delta brain-wave activity gradually increases.
     Stage 3 and Stage 4 NREM
• Stages 3 and 4 of NREM are physiologically very similar. Both
  stages are defined by the amount of delta brain-wave activity. In
  combination, stages 3 and 4 are sometimes referred to as slow-
  wave sleep.
• When delta brain waves represent more than 20 percent of total
  brain activity, the sleeper is said to be in stage 3 NREM.
• When delta brain waves exceed 50 percent of total brain activity, the
  sleeper is said to be in stage 4 NREM. During the 20 to 40 minutes
  spent in the night's first episode of stage 4 NREM, delta waves
  eventually come to represent 100 percent of brain activity. At that
  point, heart rate, blood pressure, and breathing rate drop to their
  lowest levels. However, his muscles are still capable of movement.
• The sleeper is approximately 70 minutes into a typical night's sleep
  and immersed in deeply relaxed stage 4 NREM sleep. At this point,
  the sequence reverses. In a matter of minutes, the sleeper cycles
  back from stage 4 to stage 3 to stage 2 and enters a dramatic new
  phase: the night's first episode of REM sleep.
                      REM Sleep
• During REM sleep, the brain becomes more active, generating
  smaller and faster brain waves. Visual and motor neurons in the
  brain activate repeatedly, just as they do during wakefulness.
• Dreams usually occur during REM sleep. Although the brain is very
  active, voluntary muscle activity is suppressed, which prevents the
  dreaming sleeper from acting out those dreams.
• REM sleep is accompanied by considerable physiological arousal.
  The sleeper's eyes dart back and forth behind closed eyelids-the
  rapid eye movements. Heartrate, blood pressure, and respirations
  can fluctuate up and down, sometimes extremely. Muscle twitches
  occur. In both sexes, sexual arousal may occur, which is not
  necessarily related to dream content.
• This first REM episode tends to be brief, about 5 to 15 minutes.
  From the beginning of stage 1 NREM sleep through the completion
  of the first episode of REM sleep, about 90 minutes have elapsed.
   Beyond the First 90 Minutes
• Throughout the rest of the night, the sleeper cycles
  between NREM and REM sleep. Each cycle lasts about
  90 minutes on average, but the duration of cycles may
  vary from 70 to 120 minutes.
• Usually, four more 90-minute cycles of NREM and REM
  sleep occur during the night. Just before and after REM
  periods, the sleeper typically shifts position.
• Stages 3 and 4 NREM, slow-wave sleep usually occur
  only during the first two 90-minute cycles. As the night
  progresses, REM sleep episodes become increasingly
  longer and less time is spent in NREM.
• During the last two 90-minute sleep cycles before
  awakening, NREM sleep is composed primarily of stage
  2 sleep and periods of REM sleep can last as long as 40
  minutes.
Disrupting the sleep-wake cycle
• As with many other physiological processes, sleep is
  linked to a 24-hour circadian rhythm and affected by
  signals such as light and dark. The effects of disrupting
  the sleep-wake cycle can be seen in jet lag, which is
  characterized by fatigue, irritability, lack of alertness, and
  sleeping problems.
• A person affected by jet lag feels like sleeping at the
  wrong times of day. It has been found that the body
  maintains a circadian sleep-wake rhythm even in the
  absence of external cues like lightness and darkness,
  although research subjects deprived of such cues
  eventually adopt a 25-hour “day.”
• The “internal clock” that maintains this pattern is a
  section of the brain called the supra chiasmatic nucleus
  (SCN), located in the hypothalamus.
 Disorders interfering with sleep
• Various disorders interfere with sleep. The most common is
  insomnia, the inability to fall asleep or stay asleep. Nearly
  one-third of all Americans are affected by some degree of
  insomnia. Often associated with mental distress, insomnia is
  treated with medication, psychotherapy, relaxation
  techniques, or a combination of these methods.
• The medications most commonly prescribed are
  benzodiazepines (Valium, Halcyon, Restoril) and barbiturates.
  While they alleviate insomnia in the short run, these drugs
  interfere with normal sleep patterns, and can lead to
  increased tolerance and dependence.
• Researchers and clinicians have had success treating
  insomnia with the hormone melatonin, a naturally occurring
  substance related to sleep onset and secreted by the pineal
  gland.
                  Sleep disorders
• Narcolepsy, a disorder characterized by sudden and uncontrollable
  occurrences of sleep, afflicts 100,000 people in the United States.
  This condition is genetically linked, and may be curable in the future.
  Individuals affected by narcolepsy abruptly enter REM sleep states
  during the daytime, collapsing and remaining immobile for a period of
  time after awakening. Napping and stimulants have both been used to
  treat this condition.
• Another disorder associated with sleep is sudden infant death
  syndrome (SIDS), in which a healthy baby stops breathing during
  sleep, fails to awaken, and suffocates. While the exact cause of SIDS
  is unknown, researchers are attempting to identify and save at-risk
  infants by studying the relationship between the disorder and sleeping
  patterns.
• In sleep apnea, a person repeatedly stops breathing while asleep but
  awakes each time. The disrupted sleep that results from these
  multiple awakenings leaves the sleeper fatigued and sleepy during the
  daytime.
• Night terrors are non-REM dream experiences from which the
  sleeper never fully awakes and which he or she does not recall upon
  awakening. This condition mostly occurs in children and can be
  treated with hypnosis or medication in severe cases.
       Chronic sleep problems
• An estimated 15 percent of Americans have
  chronic sleep problems, while about 10 percent
  have occasional trouble sleeping.
• Sleep disorders are listed among the clinical
  syndromes in Axis I of the American Psychiatric
  Association’s Diagnostic and Statistical Manual
  of Mental Disorders.
• They may be either primary (unrelated to any
  other disorder, medical or psychological) or
  secondary (the result of physical illness,
  psychological disorders such as depression,
  drug or alcohol use, stress, or lifestyle factors,
  such as jet lag).
             Sleep deprivation
• Sleep deprivation appears to be a precipitating factor for
  seizures in some people with epilepsy. The reason why
  this should be so is unclear. It may be due to
  neurochemical or hormonal changes or it is possible that
  the normal increase in protein synthesis that occurs in
  sleep may be impeded, thereby diminishing cellular
  repair mechanisms and rendering brain cells more open
  to epileptic activity. However, sleep deprivation may also
  be used by doctors to activate EEG abnormalities in
  patients when a diagnosis of epilepsy is unclear.
• In conclusion, people whose seizures are triggered by
  changes in sleep patterns should be advised to maintain
  reasonably regular hours of retiring and awakening, to
  obtain sufficient sleep, and to avoid shift work or other
  causes of disrupted sleep-waking rhythms. There is not
  need to exceed average hours of sleep to reduce the
  chances of seizures occurring.
                          Hypnosis
• Certain waking states, which are accompanied by marked
  changes in mental processes, are considered states of altered
  consciousness. One of these is hypnosis, a highly responsive
  state induced by a hypnotist through the use of special techniques.
  While the term “hypnosis” comes from the Greek word for sleep
  (hypnos), hypnotized people are not really asleep. Their condition
  resembles sleep in that they are relaxed and out of touch with
  ordinary environmental demands, but their minds remain active
  and conscious.
• Other characteristics of hypnosis include lack of initiative, selective
  redistribution of attention, enhanced ability to fantasize, reduced
  reality testing, and increased suggestibility. Also, hypnosis is often
  followed by post-hypnotic amnesia, in which the person is unable
  to remember what happened during the hypnotic session.
• Hypnosis has proven useful in preventing or controlling various
  types of pain, including pain from dental work, childbirth, burns,
  arthritis, nerve damage, and migraine headaches.
                Degrees of hypnosis
• There are three degrees of hypnosis. Under light hypnosis, the
  subject becomes sleepy and follows simple directions; under
  deep hypnosis, the person experiences dulling of sensory
  perception, similar to that of anesthesia.
• Under deep hypnosis, the subject can move about, open his or
  her eyes, and can even undergo medical procedures with no
  additional anesthetic. Magicians and illusionists use deep
  hypnosis to make a subject behave in unusual ways, such as to
  suspend the subject’s body between two chairs in a posture that
  is completely stiff. The magician suggests that the subject’s body
  become stiff and rigid, and the result is muscle tension powerful
  enough to support the body completely.
• Many researchers contend that the key factor in hypnosis is the
  subject’s willingness to cooperate with the hypnotist, combined
  with the subject’s belief that hypnosis works. People who are
  easily hypnotized are described as “suggestible”; in fact, if the
  subject expects to be successfully hypnotized, it is much more
  likely that he or she will.
              Hypnotic induction
• Hypnotic induction is the process by which hypnosis is
  accomplished. In most situations, an individual performs the
  induction on a willing subject. Classical hypnotic induction
  involves a series of steps.
• First, sensory input to the subject is restricted, and the subject
  is instructed to stop moving. Second, the subject’s focus of
  attention is narrowed. This may be accomplished by asking
  him or her to focus on a specific point of light or a spot on the
  wall.
• Finally, the hypnotist begins a pattern of monotonous
  repetition.
                 Employ hypnosis
• Doctors also employ hypnosis as a method of pain
  management for chronic headaches, backaches, severe
  burns, and during childbirth. In cancer treatment, hypnosis is
  used to control the side effects of chemotherapy and as a
  self-healing adjunct to chemotherapy.
• Hypnosis is also used for autoimmune diseases, sleep
  disorders, and skin ailments, including warts and rashes.
  Some surgeons use hypnosis in the operating room, not
  only to reduce the amount of anesthesia patients need, but
  also to lessen anxiety and postoperative swelling and
  bleeding.
• A patient in an hypnotic trance can remain immobile for
  extended periods of time, avoiding aggravation of the injury.
• Victims under a state of shock are also more responsive to
  hypnotic induction. Dentists use hypnosis to complete dental
  work on a relaxed patient without the need for anesthesia.
     Professional organizations
• A number of professional organizations offer training and
  advanced training in hypnosis.
• Among these are the American Society of Clinical
  Hypnosis, the American Board of Medical Hypnosis, the
  American Board of Psychological Hypnosis, the
  American Board of Hypnosis in Dentistry and the
  American Hypnosis Board for Clinical Social Work. The
  American Psychiatric Association, the American
  Psychological Association, and the American Dental
  Association have all endorsed the technique.
• Mental health professionals have used hypnosis to treat
  sexual dysfunction, eating disorders, smoking and other
  addictions, enuresis and thumb-sucking.
                    Meditation
• In meditation, an altered state of consciousness is
  achieved by performing certain rituals and exercises.
  Typical characteristics of the meditative state include
  intensified perception, an altered sense of time,
  decreased distraction from external stimuli, and a sense
  that the experience is pleasurable and rewarding.
• While meditation is traditionally associated with Zen
  Buddhism, a secular form called Transcendental
  Meditation (TM) has been widely used in the United
  States for purposes of relaxation. It has been found that
  during this type of meditation, people consume less
  oxygen, eliminate less carbon dioxide, and breathe more
  slowly than when they are in an ordinary resting state.

								
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