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Lecture 6

Psychology 1000 Lecture Notes - Lecture 6: Circadian Rhythm, Suprachiasmatic Nucleus, Pineal Gland


Department
Psychology
Course Code
PSYCH 1000
Professor
John Campbell
Lecture
6

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Psychology Chapter 6
The Puzzle of Consciousness
Consciousness: defined as our moment to moment awareness of ourselves and our
environment. Consciousness is:
- subject and private
- dynamic (ever changing)
- self reflective and central to our sense of self
- intimately connected with the process of selective attention
The following are used to measure states of consciousness: self-report, physiological
measures, behavioral measures
Levels of Consciousness
- Awareness of the relationship between self and the external world
- Monitoring- keeping track of self
- Control- planning
- Three levels of awareness: conscious mind of which we are currently aware,
preconscious mind of which are outside our current awareness but can be recalled
under certain conditions, and unconscious events that cannot be brought into
conscious awareness under ordinary circumstances
The Cognitive Unconscious
- Controlled processing is the voluntary use of attention and conscious effort.
- Automatic processing can be performed with little or no conscious effort. This occurs
mostly when we carry out routine or well learned tasks.
- The stroop effect: when words of colours are displayed in different colours and
the task is to name the displayed colour
- Divided attention is facilitated by automatic processing. It is the ability to perform
more than one activity at the same time. For example, we can talk while we walk, type
as we read, etc.
- The emotional unconscious often effects a person without their realizing. For example
if you are in a good or bad mood and don’t know why, it is often because your
environment has effected you without your realizing.
- Our subjective experience of consciousness arises from the integrated activity of the
various modules, somewhat akin to listening to a choir sing.
Circadian Rhythms: Our daily biological clocks
- Our circadian rhythms are our daily (24hr) biological cycles that are controlled by
hormone secretions, etc.
- Most of these rhythms are regulated by the brain’s suprachiasmatic nuclei which is
located in the hypothalamus, which works at the brain’s clock.
- SCN neurons like to the tiny pineal gland which secretes melatonin which has
relaxing effects on the body. The neurons are active during the daytime
decreasing output of melatonin and inactive at night, increasing melatonin.
- Our eyes are also connected to the SCN which results in our sensitivity to light
and dark and how that effects our sleep cycle.
Environmental Disruptions of Circadian Rhythms

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- Seasonal affective disorder (SAD) is a cyclic tendency to become psychologically
depressed during certain months of the year. People who suffer from this may have
circadian rhythms particularly sensitive to light, as they offer suffer in the winter time.
- Jet lag is also a circadian disruption and is a big concern for business people, athletes,
etc.
- Night shiftwork also disrupts circadian rhythms. Some people have an easy time
adjusting while others have an extremely difficult time.
- Even small adjustments to our circadian rhythms greatly increase accidental death or
accidents.
Sleep and Dreaming
- Sleep, just as being awake does, involves certain levels of alertness and
consciousness.
- Sleep research is carried out in labs using EEG recordings to watch the brain’s
electrical activities in a pattern of beta waves (40cps) which show when you are
awake and alert. They have a high frequency but a low amplitude. When you begin to
fall asleep your brain switches to alpha waves at about 8 to 12 cps (cycles per
second).
Stage 1 through Stage 4
- As sleep beings, slower, theta waves (6cps) increase which puts you into a light sleep
(stage 1)
- As sleep becomes deeper, sleep spindles appear which are rapid bursts of brain
activity (12-16cps) followed by a k-complex which is a very slow wave (1-2 cps) (stage
2)
- In stage 3 sleep deepens and is marked by slow large delta waves (1cps)
- When delta waves dominated the EEG pattern you are in stage four. Both stage 3 and
4 are referred to as slow wave sleep.
- In 60 to 90 minutes you complete a cycle of stages 1-2-3-4-3-2
REM Sleep
- At this point, a different stage of sleep ensues, every half minute bursts of muscular
activity cause the sleepers’ eyeballs to vigorously move back and forth between the
closed eyelids
- During this period, dreams are almost always reported
- In REM sleep, physiological arousal may increase to daytime levels in areas such as
heart or breathing rate.
- Dreams still occur in non-REM sleep except they are shorter and less story like.
- Each cycle takes about 90 minutes, as hours pass however, stage 3 and 4 drop out
and REM becomes longer.
Getting a Night’s Sleep: Brain and Environment
- Areas at the forebrain and within the brain stem are particularly important in regulating
our falling asleep
- Sleep is biologically regulated but the environment plays a large role as well such as
noise, stress levels, etc.
How Much do we sleep?
- 15-24 year olds average 8.5 hours a day and elderly adults average just under 6 hours

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- By late adult hood we get relatively little sound wave sleep
- How much sleep a person needs is influenced by genetic factors, work schedules,
stress, age, and general health
Sleep Deprivation
- In a study, the average sleep deprived person functioned only as well as someone in
the bottom 9 percent of non-deprived participants.
- If sleep deprived, it takes several nights to recover, although we do not make up all the
sleep time that we have lost.
Why do we sleep?
- According to the restoration model, sleep recharges our run-down bodies and allows
us to recover from physical and mental fatigue. Sleep deprivation and night shift work
studies strongly support this view: We need sleep to function at our emotional, mental,
and physical best.
- Activities that increase daily wear on the body should increase sleep.
- A cellular waste product called adenosine may play a role in chemical changes in our
sleep. As it accumulates, it influences brain processes that decrease alertness and
promote sleep.
- Evolutionary/circadian sleep models emphasize that sleep’s main purpose is to
increase a species’ chances of survival in relation to its environmental demands. For
example, our ancestors had much to gain my sleeping at night, as hunting and food
gathering were more safe and easier during the day.
- We need to have REM sleep as it is vital for mental functions. The high level of brain
activity during REM sleep may help strengthen the neural circuits involved in
remembering important information from the preceding day.
Sleep Disorders
- One half to two thirds of North American adults feel that they have some type of sleep
problem.
- Insomnia: refers to chronic difficulty in falling asleep, staying asleep, or experiencing
restful sleep. Insomnia has biological, psychological, and environmental causes. Some
people are genetically predisposed to insomnia, and medical conditions, mental
disorders such as anxiety and depression, and many drugs can disrupt sleep.
Psychologists have developed many non-drug methods in treating insomnia. The
different types of insomnia are expectational insomnia, situational insomnia, and
chronic insomnia. Some people have a thermoregulation problem and can’t lower their
body temperature, therefore a normal sleep cycle fails to develop.
- Sleep Apnea: interruption in breathing during sleep. Normal during sleep, however
people with the disorder do not start breathing again unless they wake up. People with
a severe form of this disorder may stop breathing for up to a minute hundreds of time
in the night. This is a problem because it causes chronic insomnia. This is due to an
obstruction of air passages, or abnormal brain function. This sometimes causes SID
(sudden infant death).
- Narcolepsy: involves extreme daytime sleepiness and sudden, uncontrollable sleep
attacks that may last from less than a minute to an hour. When this occurs
narcoleptics go right into REM sleep, and sometimes have intense dreamlike visual
images and sounds. Sometimes they experience cataplexy, a sudden loss of muscle
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