Characteristics and Patterns of Sleep and Sleep Phenomenas

80% of our sleep.
First half of sleep is more NREM than second

Hypnogogic state - experienecd at beginning of sleeep cycle and lasts 1-2 minutes

Characterised by slow rolling eye movement
May experience light bursts of dream-like colour, as body is entering stage of deep mental/physical relaxation

A decrease in Alpha waves as they are replaced by Theta waves

Frequency - irregular, slightly slower than beta waves
Amplitude - Mixture of high and low

As we drift in and our of our true sleep state
Lasts 5 - 10 minutes

Decrease in HR, Body temperature, beathing rate, muscle temperature -

- as a result of the body relaxing we experience a hypnic jerk

Mainly theta waves
Frequency - slightly lower than in stage 1
Amplitude - slightly higher amplitude than stage 1
Bursts of sleep spindles (high frequency)
K complex (single burst of high amplitude and lower frequency waves)

Lasts 10 - 20 minutes
Light stage of sleep
Able to respond to stimuli
sleep spindles - high frequency
their presence indicates that the person is truly asleep
K complex single sharp bursts of lower frequency high amplitude waves
in response to arousing stimuli

Light stage of sleep can be easily aroused - 7/10 will say they weren't sleeping; just dozing and thinking.

Body movements lessen HR, body temp, continue to decrease
Breathing becomes slower & more regular

Reduction in brain activity
Theta waves and 20-50% Delta waves
Frequency - lower than the alpha/theta wave of s 1&2
Amplitude - higher than previous stages
Presence of Delta waves marks SWS

Start of the deepest period of sleep
about 10 minutes
known as 'moderately deep sleep'
SWS begins within an hour of being asleep and lasts for 30

HR BP and Body tempt continue to drop
Individual is relaxed and less responsive to outside world
Hard to arouse - if awoken groggy/disorientated

More than 50% Delta waves
Slowest and largest brain waves
Frequency - lowest
Amplitude - highest

Deepests stage of sleep cycle "very deep sleep"
First cycle = 20 minutes
-As night progresses, less time is spent in 3&4
Stage 1-3 = 45 - 60 minutes, then we move back up 3, 2, to 1 and back again

Muscles ccompetely relaxed barely move
Sleep phenomena may occur, sleep walking, bed wetting, terrors, nightmares,

VERY difficult to wake - if woken individual can take up to 10 minutes to orientate
Poor memory of sleep events - sleep inertia

Irregular, low amp high frequency beta waves