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Chapter 5.1

PSYCH101 Chapter Notes - Chapter 5.1: Ultradian Rhythm, Circadian Rhythm, Sleep Spindle


Department
Psychology
Course Code
PSYCH101
Professor
Richard Ennis
Chapter
5.1

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5.1 - Biological Rhythms of Consciousness: Wakefulness
and Sleep
February 7, 2018
9:42 AM
REM behaviour disorder - acting out dreams in reality
Ex. Jumping out of windows, hitting/choking bed partner
Consciousness - a person's subjective awareness, including thoughts, perceptions, experiences of
the world, and self-awareness
What is Sleep?
Biological Rhythms
Biological rhythms - biological patterns adapted to the cycles of organisms' environment
Circannual rhythm - yearly cycle
Infradian rhythm - any rhythm that occurs over a period of time longer than a day
Ultradian rhythm - homeostasis activity occurring in 90-120-minute cycles
Circadian rhythms - internally driven daily cycles of approx. 24 hours affecting
physiological and behavioural processes
Entrainment - when biological rhythms become synchronized to external cues such as
light, temperature, or even a clock
Endogenous rhythms - biological rhythms generated by our body independent of
external cues such as light
Stages of Sleep
Polysomnography - set of objective measurements used to examine physiological variables
during sleep
Electroencephalogram (EEG) - device that measures brain waves using sensors attached to
the scalp
Frequency - number of up-down cycles every second
Amplitude - height and depth of up-down cycles
Beta waves - high-frequency, low-amplitude waves characteristic with wakefulness
Alpha waves - signal that a person may be daydreaming, meditating, or starting to fall
asleep
Stage 1 → brain waves slow down and become higher in amplitude → theta waves
→ breathing, blood pressure, and heart rate decrease slightly as sleep begins
→ individual still sensitive to noises at this stage
Stage 2 → approx. 10-15 minutes after stage 1
→ brain waves continue to slow
sleep spindles - clusters of high-frequency but low-amplitude waves
K complexes - small groups of larger amplitude waves
→ individual responds to fewer external stimuli
Stage 3 → Approx. 20 minutes after stage 2
→ brain waves continue to slow down, becoming delta waves - large, looping
waves that are high-amplitude and low-frequency
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Stage 4 → sleep cycle reverses
REM sleep - stage of sleep characterized by quickening brain waves, inhibited
body movement, and rapid eye movements (REM)
→ cycle back into REM every 90-100 minutes
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Quick Quiz - What is Sleep?
1. Large, periodic bursts of brain activity that occur during Stage sleep are known as
__________.
a. Beta waves
b. Sleep spindles
c. Delta waves
d. Alpha waves
2. Why is REM sleep known as paradoxical sleep?
a. The bran waves appear to be those of an awake person, but the individual seems to be
in a deep sleep
b. The brain waves resemble those of a sleeping individual, but the person behaves as if
they are nearly awake
c. The brain wave patterns in REM sleep are totally unlike those produced by brain
activity at any other time
d. The brain waves resemble those of a sleeping individual, and the person seems to be
in a very deep sleep
3. Which of the following is the most likely order of sleep stages during the first 90 minutes
of a night of rest?
a. Stages 1-2-3-4-1-2-3-4-REM
b. Stages 1-2-3-4-REM-1-2-3-4
c. Stages 1-2-3-4-3-2-1-REM
d. Stages REM-4-3-2-1
ANSWERS: 1.b 2.a 3.c
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Why We Need Sleep
Theories of Sleep
Restore and repair hypothesis - idea that the body needs to restore energy levels and repair
any wear and tear experienced during the day's
activities
Preserve and protect hypothesis - suggests that two more adaptive functions of sleep are
preserving energy and protecting the organism from
harm
Sleep Deprivation and Sleep Displacement
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