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Slide 2

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Stage 1.
· Light sleep,
· Eye & muscle
The Sleep Cycle. · Heart and breathing
rates increase,
· Quick & irregular
activity slow, eye movements,
· 50% brain activity · BP rises,
decrease. · Shallow breathing,
· Sleeper may Most people complete · Chin, neck, torso
experience muscle five complete cycles, and limb muscles
contractions each lasting 90-110 paralysed,
(`Hypnogogic state') minutes. · Dreaming begins,
Stage 2.
· Eye movement Stage 3. Stage 4.
stops, · Deep sleep · Deep sleep,
· Muscle activity begins, · Brain only
stops, · Brainwaves produces delta
· Brainwaves produce v. slow waves,
slow, delta waves, · No eye/muscle
· Sleep spindles · No eye/muscle movement,
begin, movement, · Sleeper may be
· Difficult to awake, disorientated if
awoken…read more

Slide 3

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`Theta waves' ­
Associated with
Found in stage 1.
`Sleep spindles' - Occur
during stage 2, may
represent periods where
the brain is inhibiting
processing to keep the
sleeper in a tranquil state .
`K Complexes' - Also occur during stage 2.
They suppress cortical arousal in response
to stimuli that the sleeping brain evaluates
not to signal danger, and second, aiding
sleep based memory consolidation. They
consist of a brief high-voltage energy burst,
often of more than 100 µV…read more

Slide 4

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Delta Waves ­ Occur
during stages 3 & 4 and
are the slowest of the
brain waves.…read more


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