Unit 3 Psychology
RAH
CHARACTERISTICS AND PATTERNS OF
SLEEP
TYPES OF SLEEP
NREM Sleep (non rapid eye movement sleep)
 REM Sleep (rapid eye movement sleep)
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These occur in continuous cycles, with one following the
other.
 In adults, one cycle of NREM sleep last for about 70 to
90 and consists of 4 distinct stages (identified by
different brain wave patterns).
 REM follows each period of NREM sleep.
 A complete sleep cycle last for about 80 to 120 minutes
and we repeat if 4 or 5 times during 8 hours of sleep.
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NREM SLEEP
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Approx 80% of our sleep
time is NREM.
Brain active during NREM
Believed that it is the time
when the body recovers:
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Repairing body tissue
Removing waste products
Replenishing
neurotransmitters
E.g. Increase in deep
sleep experienced in
NREM after vigorous
exercise.
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NREM consists of 4 stages
from light sleep to the
stage of deepest sleep and
back to light sleep.
Every stage is dominated
by a particular brain wave
pattern.
Frequency
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Number of brain waves
Amplitude
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Intensity of brain wave
HYPNOGOGIC STATE
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Transition period from
being awake to being
asleep.
May last a minute or 2.
People may experience:
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Flashes of light or colour
Floating or weightlessness
Dreamlike images
Swift jerky movements
Sense of falling or slipping
NREM – STAGE 1
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Occurs as we drift into and out
of a true sleep state.
Physiological changes:
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Decrease in heart rate
Respiration
Body temp
Muscle tension
Hypnic Jerk: muscles relaxing
can result in ‘jerking’ (spasm).
Decrease in alpha waves and
replaced by theta waves.
Lasts for about 5-10 minutes.
NREM – STAGE 2
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Light stage of sleep.
Point where you are truly
asleep.
Easily awakened.
Lasts approx 20 mins.
Body movements lessen.
Temp continues to fall.
Heart rate slower.
Mainly theta waves.
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Sleep spindles:
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Brief bursts of higher
frequency of brain wave
activity.
An indicator that a person is
truly asleep.
Brain still responds to
various external and
internal stimuli, e.g.
someone entering the
room.
This stage is still
considered to be light.
NREM – STAGE 3
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Start of deepest period of
sleep.
Referred to as moderately
deep sleep.
Heart rate, blood pressure and
body temp continue to drop,
breathing continues to be slow
and steady.
Relaxed and less responsive.
Delta waves begin to appear.
Slow large, regular, brain
waves.
Slow waves sleep (SWS).
Generally begins ½ hour into
sleep.
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When EEG recordings show that
delta waves comprise more
than 50% of the brain wave
activity, the person has entered
stage 4.
NREM – STAGE 4
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Deepest stage of sleep.
Very deep sleep.
Muscles completely relaxed.
Delta waves dominate.
Difficult to wake person.
Sleep inertia – post awakening
mental lag.
1st cycle – 20mins.
As night progresses, less and
less time is spent in stages
3&4.
Sleep walking, sleep talking
and night terrors (and
bedwetting) occur.
NREM CYCLE CONCLUSION
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NREM cycle from stage
1-4 takes about 45-60
minutes.
We then move
progressively up through
stages 3,2 and 1.
Our brain and body
respond as if we are at
the point of waking up.
These are signs of
moving into REM.
REM SLEEP
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Period of Rapid Eye
Movement sleep during
which the eyeballs rapidly
move beneath the closed
eyelids.
Brain wave pattern is
irregular.
Low amp/high frequency
beta waves.
REM considered to be
deep sleep, as people are
difficult to wake during
this period.
REM SLEEP – PHYSIOLOGICAL CHANGES
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Internal functioning
more active during REM
the during NREM.
Heart faster and more
irregular.
Blood pressure rises.
Breathing faster and
more irregular.
Yet, sleeper is totally
relaxed.
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Also called paradoxical
sleep – internally, the
brain and body are
active, yet body appears
calm and inactive.
REM SLEEP - DREAMING
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Most dreaming occurs during
REM.
Research suggest we dream
several times a night.
Specific movements for eye
movements is unclear.
It’s believe to be related to
physiological activity that is
occurring at the same time as
random, neural activity of the
brain.
Purpose of REM unclear.
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Some research suggests that
REM assists in consolidating of
embedding new memories in
the brain by strengthening newly
formed neural connections.
General agreement that REM
probably serves some biological
need.
Throughout the night, we pass
continuously through NREM and
REM sleep cycles, with REM
periods lengthening and
occurring closer together as the
night progresses.