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Summary Task 4 - The sleepwalking killer
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Summary of Task 4 in Forensic & Legal Psychology in a Nutshell
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TASK 4: THE SLEEPWALKING KILLERWHAT IS SLEEPWALKING? & WHAT ARE SLEEP DISORDERS?
SLEEPWALKING (DE COCK)
Sleepwalking (SW) – ambulation occurring during sleep, with a persistence of sleep, an
altered state of consciousness or an impaired judgement during ambulation
Difficult to arouse, confused when awakened, mostly amnesic of the episode
Can consist (1) in routine behaviours that occur at inappropriate times, (2)
inappropriate / nonsensical behaviour, (3) dangerous / potentially dangerous
behaviours
Frequent in children & adolescents BUT mostly disappears in adulthood
Anything that messes with your sleep cycle increases the risk of sleepwalking
Some drug treatments for other conditions facilitate SW episodes (e.g.,
antidepressants, antipsychotics)
WHILE YOU WERE SLEEPWALKING: SCIENCE & NEUROBIOLOGY OF SLEEP DISORDERS & THE ENIGMA
OF LEGAL RESPONSIBILITY OF VIOLENCE DURING PARASOMNIA (POPAT & WINSLADE)
STAGES OF SLEEP
NREM sleep – divided into 4 stages
1st stage: thoughts start to drift, ability to react to external stimuli decreases,
muscle activity slows down
As one moves through the stages – EEG waves grow in amplitude & decrease in
frequency
Stage 3-4: “deep” stages of NREM sleep – waking someone difficult & person feels
groggy & disoriented
REM sleep – dream mentation, effortless person wakes up with little disorientation
CLINICAL ASPECT OF SLEEP DISORDERS
Dyssomnias – manifest as “excessive sleepiness or difficulty in initiating / maintain
sleep”
Insomnia, narcolepsy, circadian rhythm disorders
Rarely become violent in a way in which they could be mistaken for awake &
aware actions
Parasomnias – during sleep, marked by sig. skeletal muscle activity
Result in physical actions that are completely uncharacteristic of sleep
Somnambulism sleepwalking
REM sleep behaviour disorder (RBD)
Somnambulism Sleepwalking, occurs during deepest stages of NREM sleep (stages 3+4)
, More likely to occur in earlier part of the night when these stages
predominate
Episodes typically last from a few minutes to an hour, can occur from
once a month to multiple nights per week
Individual appears awake but is unresponsive + no memory of
episode
State dissociation theory
States of wakefulness & sleep are not mutually exclusive & can
mix / oscillate rapidly
SW – body’s physiological mechanisms prepare to enter deep
stages of NREM sleep, some important mechanisms don’t occur
sig. motor activity remains
Support: EEG shows waves characteristic of stage 3+4 & awake
states
SW = combination of NREM sleep & wakefulness
RBD Occurs during REM sleep ( early morning) & muscle atonia is disabled
for the episode
State dissociation theory
RBD is combination of REM sleep & wakefulness
BUT individuals with RBD tend to awaken as their feet hit the
floor / soon after
o Common victims: bed partner / those nearby
Acting out ones dreams, individual will remember bits & pieces
Doesn’t appear disoriented after awaking them
Strong connection between RBD & degenerative neurological diseases such as
Parkinson’s disease, dementia with Lewy body disease
Over 2/3 of patients diagnosed with RBD will develop symptoms
of above disorders
NEUROBIOLOGY OF PARASOMNIAS
Alpha motor neurons control skeletal muscle fibres responsible for majority of body
movements
During sleep input signals to these neurons change
Excitatory impulses decrease & Inhibitory impulses increase cell is hyperpolarised
o Much larger excitatory impulse required than from resting potential
o Transmitting action potential to skeletal muscle is less likely
Regions of brainstem & cerebellum have been found to contribute to activity of motor
neurons
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