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Sleep and Dreams
 Circadian Rhythm
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regular bodily rhythms, such as of wakefulness and body temperature,
that occur on a 24-hour cycle
controlled by a cluster of neurons in the hypothalamus called the
suprachiasmatic nucleus (SCN)
 Uses environmental cues such as sunlight to help turn on and off
Sleep Deprivation
 Effects of Sleep Loss
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fatigue
impaired concentration
depressed immune system
greater vulnerability to accidents
lessened ability to deal with stress
weight gain
heart disease
Sleep and Dreams
 Sleep
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periodic, natural, reversible loss of
consciousness
Sleep and Dreams
 Two theories about why we sleep:
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Restorative Theory of Sleep
Adaptive Theory of Sleep
Sleep and Dreams
 Stages of Sleep:
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Stage 1 (NREM)
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transitional stage only lasting a few minutes
can quickly gain consciousness
will sometimes experience hypnagogic sensations
Sleep and Dreams
 Stages of Sleep:
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Stage 2 (NREM)
 when true sleep begins
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brain activity slows except for brief bursts that last a second or two
called sleep spindles
breathing becomes rhythmic
slight muscle twitching
lasts about 15 to 20 minutes
Sleep and Dreams
 Stages of Sleep:
 Stages 3 & 4 (NREM)
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both stages similar except for the amount of delta wave activity in the brain
 when reaches 100% delta wave activitty, heart rate, blood pressure, and
breathing rate reach their lowest
if briefly awakened, usually not remembered
night terrors and sleep walking will sometimes occur in stage 4
by end of this stage, person has been sleeping approx. 70 minutes
Sleep and Dreams
 Stages of Sleep
 REM sleep
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visual and motor neurons become more active
voluntary muscle activity is suppressed
considerable physiological arousal occurs such as rapid eye movements,
heart rate, blood pressure and breathing fluctuate, muscle twitches, and
sexual arousal
often change position before and after
completes cycle (approx. 90 minutes)
Dreams
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Usually occur during REM sleep
Do not recall about 95 % of dreams we have. Possibly due to:
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changes in brain chemistry and functioning fail to support the information
processing and storage needed to remember (frontal lobes,
neurotransmitters)
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tend to remember the more vivid dreams
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distractions upon awakening can cause us to forget
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difficult to remember any experience while asleep
Common Dreams
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Falling / Flying
Public exposure / nudity
Being chased
Bad or missing teeth
Ill or dying
School / work
Missing appt. / transportation
Being late
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Running / getting no where
Paralysis
Snakes / spiders
Can’t breath / suffocating
Water
Trapped
Lost
Faulty machinery
Typical Characteristics of
Dreams
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Have several characters
Involve motion (running, walking, falling, etc.)
Usually indoors
Visual sensations but rarely taste, smell, or pain
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Sighted individuals often dream in color
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Blind do not see things but experience other sensations
Typical Characteristics of
Dreams
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Disregard physical laws (flying, falling w/o injury)
May be recurrent (threatened, pursued, etc.)
Involve anxiety or fear more than joy and happiness
Rarely involve sexual encounters
Dream Theories
 Psychoanalytic/Psychodynamic
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Freud believed that dreams were “disguised fulfillments
of repressed wishes” and their interpretation provided the
“royal road to the knowledge of the unconscious mind”
Dream Theories
 Psychoanalytic/Psychodynamic
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safety valve for the release of unconscious and
unacceptable urges
comprised of two components:
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manifest content: the actual dream image
latent content: the disguised, psychological meaning of the
dream
Dream Theories
 As Information Processing
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helps facilitate memories
 As a Physiological Function
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periodic brain stimulation
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Activation-Synthesis Model
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Limbic System structures such as the amygdala and hippocampus are
activated,
The brain synthesizes and integrates memory fragments, emotions, and
sensations that have been triggered internally
Dreaming is our subjective awareness of these random bursts.
Sleep Disorders
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Insomnia
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persistent problems in falling or staying asleep
Narcolepsy
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uncontrollable sleep attacks
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possibly due to the absence of a hypothalamic neural center that
produces hypocretin
Sleep Apnea
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temporary cessation of breathing during sleep
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momentary re-awakenings