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Chapter 6

Psychology 1000 Chapter Notes - Chapter 6: Circadian Clock, Circadian Rhythm, Seasonal Affective Disorder

Course Code
PSYCH 1000

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- consciousness: our moment-to-moment awareness of ourselves and our
environment several characteristics:
osubjective and private: other ppl cannot know what is reality for you
odynamic (ever changing): we drift through various states each day
oself-reflective and central to our sense of self: the mind is aware of its own
ointimately connected with the process of selective attention: consciousness
consists in the selection of some stimuli, and the suppression of others
Measuring States of Consciousness
-self-report: (most common) ppl describe their inner experiences most direct
insight, but not always verifiable
-physiological measures: establish the correspondence between bodily states and
mental processes objective, but cannot tell us what a person is experiencing
-behavioural measures: includes performance on tasks also objective, but still
cannot tell what a person is experiencing subjectively
Levels of Consciousness: Psychodynamic and Cognitive Perspectives
-Freud proposed that the human mind consists of three levels of awareness:
oThe conscious mind contains thoughts, perceptions and whatever we are
aware of
oPreconscious mental events are outside current awareness, but can easily
be recalled eg, childhood memories
oUnconscious events cannot be brought into conscious awareness under
ordinary circumstances eg, sexual urges, traumatic memories
-Behaviourists do not agree with Freud’s theory, and many cognitive and
psychodynamic psychologists believe it is out dated
The Cognitive Unconscious
-Cognitive psychologists reject the notion of an unconscious mind driven by
instinctive urges and repressed conflicts. Rather, they view conscious and
unconscious mental life as complementary forms of information processing
Controlled versus Automatic Processing
- controlled processing: the voluntary use of attention and conscious effort
- automatic processing: take little or no conscious effort (routine tasks, etc)
-things that are use conscious effort such as typing eventually become automatic
Divided Attention:
-automatic processing facilitates divided attention, the ability to perform more
than one task at a time

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The Emotional Unconscious
-modern psychodynamic views emphasize that emotional and motivational
processes operate unconsciously and influence behaviour
-these hidden processes can cause to feel and act in ways we cannot explain
The Modular Mind
-many believe the mind is a collection of largely separate but interacting modules
-these modules are info processing subsystems within the brain that perform tasks
related to sensation, perception, memory, problem solving, motor skills, etc
-the various modules process info simultaneously and mostly independently
-output from one module can provide input for another
-according to this perspective, consciousness arises from the integrated activity of
the various modules
-biological cycles within the body that occur on an approximately 24-hour cycle
Keeping Time: Brain and Environment
-most circadian rhythms are regulated by the suprachiasmatic nuclei (SCN),
located in the hypothalamus acts as the brain’s clock
-SCN neurons have a genetically programmed cycle of activity and inactivity
-They link to the tiny pineal gland, which secretes melatonin, a hormone that has a
relaxing effect on the body. During the day the SCN neurons are active reducing
the secretion of melatonin, but at night the SCN neurons are inactive, allowing
melatonin levels to increase, making you sleepy
-Circadian clock is biological, but environmental factors such as the day-night
cycle help keep SCN neurons on a 24-hour schedule
-Eyes have neural connections to the SCN light of day increases SCN activity
and helps reset the 24 hour clock if you lived in the dark, most ppl drift into a
longer cycle of about 24.2 to 24.8 hrs, called a free-running circadian rhythm
-Blind ppl may also experience free running circadian rhythms, and if they try to
go to bed at normal fixed times, may experience insomnia
Environmental Disruptions of Circadian Rhythms
- seasonal affective disorder (SAD): a cyclic tendency to become psychologically
depressed during certain months of the year
-as sunrise occurs later in winter, the daily “onset” time of their circadian clocks
may be pushed back, and then when ppl wake up in darkness, they are in
“sleepiness” mode for a long time after they wake up
-jet lag is a sudden circadian disruption caused by flying across several time zones
in one day east you loose hours, flying west day becomes longer
-accidents peak between midnight and 6:00am night shifts hard to deal with
-spend approximately 1/3 of our lives asleep
Stages of Sleep

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-approximately every 90 minutes while asleep, we cycle through different stages in
which our brain activity and other physiological responses change
-EEG recordings of the brain’s electrical activity show a pattern of beta waves
when you are awake. Beta waves have a high frequency of about 15-30 cycles per
second (cps), but a low “amplitude.” When getting tired, brain waves slow down
and alpha waves occur at about 8-12 cps
Stage 1 through 4
-Stage 1: brain-wave patterns become more irregular and slower theta waves (3.5-
7.5 cps) increase. Can easily be awakened, and lasts just a few minutes. Some ppl
experience images and sudden body jerks
-Stage 2: Sleep spindles – one or two second bursts of rapid brain-wave activity
(12-15 cps) – begin to appear. Muscles become more relaxed, and breathing and
heart rate slows down
-Stage 3: appearance of very slow (0.5-2 cps) and large delta waves. When delta
waves dominate the EEG pattern this indicates you have moved into stage 4.
-Stage 4: together, stage 3 and 4 are referred to as slow-wave sleep body is
relaxed, activity in various parts of the brain has decreased, and become harder to
-After about 20-30 minutes of stage 4 sleep, you go back through stages 2 and 3
-Within 60-90 minutes of going to sleep, complete cycle of stages 1-2-3-4-3-2
REM Sleep
-when awakened from REM sleep it is much easier to remember a dream
-during REM physiological arousal may increase to daytime levels heart rate
quickens, breathing becomes more rapid and irregular, and brain-wave activity
resembles that of active wakefulness. Men get erections, women get wet
-muscles in the arms, legs, and torso become relaxed REM sleep paralysis
-REM dreams are more story like and longer than those had in other stages, and in
them you can usually experience vivid sensory and motor elements
Getting a Night’s Sleep
-areas at the base of the forebrain (called the basal forebrain) and within the brain
stem are particularly important in regulating our falling asleep
-another brain stem area, where the reticular formation passes through the pons,
plays a key role in initiating REM sleep contains “REM-sleep On” neurons
that activate other brain systems, each responsible for a different aspect of REM
How Much Do We Sleep?
-differences in how much ppl sleep at various ages
-newborn infants sleep about 16hrs a day (about half is REM)
-19-30 year olds sleep slightly less than 8 hours of sleep a day, elderly about 6hrs
-REM decreases during infancy and early childhood, but remains stable thereafter
-Time spent in stages 3 and 4 declines
Why Do We Sleep?
- Restoration model: sleep recharges our run-down bodies and allows us to
recover from physical and mental fatigue
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