PSY100Y5 Chapter Notes - Chapter 5: Slow-Wave Sleep, Theta Wave, Sleep Spindle
CHAPTER 5: VARIATIONS IN CONSCIOUSNESS
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I. On The Nature of Consciousness
A. Introduction
1. Consciousness is the awareness of internal and external stimuli and includes:
a. Your awareness of external events
b. Your awareness of internal sensations
c. Your awareness of self as the unique being going through these experiences
d. Your awareness of your thoughts about these experiences
B. Variations in Levels of Awareness
1. Conscious and Unconscious are different levels of awareness.
C. The Evolutionary Roots of Consciousness
1. Consciousness may have allowed ancestors to think through courses of action and
their consequences, and then choose the best course, but no concrete answer.
D. Consciousness and Brain Activity
1. Electroencephalograph (EEG) – device that monitors the electrical activity of the
brain over time by means of recording electrodes attached to the surface of the scalp. i.e.
Summarizes the rhythm of activity of the brain (brain waves).
2. 4 Types of Brainwaves based on frequency – beta, alpha, theta, and delta
3. Variations in consciousness re correlated with variations in brain activity.
II. Biological Rhythms and Sleep
A. The Role of Circadian Rhythms
1. Biological rhythms are periodic fluctuations in physiological functioning. Implies
existence of “biological clocks”
2. Circadian rhythms are the 24 hour biological cycles found in humans and many other
species.
3. When the retina is exposed to light, it sends direct inputs into the SCN – the central
pacemaker located in the hypothalamus
B. Ignoring Circadian Rhythms
1. Quality of Sleep Suffers
2. Fatigue, Sluggishness, and Irritability
3. Negative impact on productivity, accident proness, quality of work, social relations,
and physical and mental health.
C. Melatonin and Circadian Rhythms
1. Hormone Melatonin – regulates human bio clock. May be effective as a mild
sedative, to treat insomnia.
III. The Sleep and Waking Cycle
A. Conducting Sleep Research
1. Used to monitor Sleep:
a. Electromyograph (EMG) – records muscle activity and tension
b. Electrooculograph – records eye movements
B. Cycling Through the Stages of Sleep
1. Stages 1: a brief transitional stage of light sleep that lasts only a few minutes.
a. Breathing and heart rate slow, muscle tension and body temp go down.
b. Alpha Waves are replaced with theta waves.
c. Hypnic jerks may occur.
2. Stages 2-4: respiration rate, heart rate, muscle tension, and body temp continue to
fall.
a. During Stage 2 (10 – 25 Min) brief bursts of higher frequency brain waves
(“sleep spindles”) appear.
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CHAPTER 5: VARIATIONS IN CONSCIOUSNESS
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b. Brain waves slowly become higher in amplitude, but lower in frequency.
3. Slow Wave Sleep – consists of sleep in stages 3 and 4, when high amp, low
frequency delta waves become prominent in the EEG readings. (lasts 30 min)
4. REM Sleep – relatively deep stage of sleep marked by REM’s, high frequency, low
amp brain waves, and dreaming
a. Irregular breathing, muscle tone is relaxed.
b. EEG records beta waves, resembling if people were awake.
c. Non Rem (NREM) consists of sleep stages 1-4, which are marked by absence
of REM’s, little dreaming, and varied EEG activity.
C. Age Trends in Sleep
1. Newborns will sleep 6-8 times in a 24 hour period for 16 hours.
2. Proportion of slow wave sleep declines and the percentage of time spent in stage 1
increases.
3. Total Sleep increases with age in a substantial portion of older people.
D. Culture And Sleep
1. Co Sleeping is the norm around most of the world.
E. The Neural Bases of Sleep
1. Regulated by structures that lie deep within the brain
2. Ascending Reticular Activating System (ARAS) consists of the afferent fibers
running through the reticular formation that influence physiological arousal.
F. The Evolutionary Bases of Sleep
1. Sleep evolved to conserve organisms’ energy.
2. Immobilization associated with sleep reduces exposure to predators and other sources
of dangers.
3. Helps animals restore energy and other bodily resources depleted by waking
activities.
G. Doing Without Sleep: Sleep Deprivation
1. Complete Deprivation
a. Negative effects on mood, performance on cognitive and perceptual motor
tasks, though they tend to be modest.
2. Partial Deprivation/Sleep Restriction
a. Occurs when people make do with substantially less sleep than normal over a
period of time.
b. Negative effects are most likely when subjects are asked to work on long
lasting, difficult, or monotonous tasks, or when repeatedly restricted to less
than 5 hours of sleep.
3. Selective Deprivation
a. REM deprivation – little impact on daily functions, but on sleep patterns, as
they shift to REM sleep quicker.
H. Problems in the Night: Sleep Disorders
1. Insomnia – chronic problem in getting enough sleep.
a. Difficulty falling asleep initially, difficulty remaining asleep, and persistent
early morning awakening.
b. Daytime fatigue, impaired functioning, lower productivity, and health problems
c. Due to Stress, disruptions of biological rhythms, or other temp circumstances.
Excessive anxiety and tension, depression, or offshoot of health problems –
back pain.
d. Increases with old age.
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