Summary Task 4 - The sleepwalking killer

TASK 4: THE SLEEPWALKING KILLER
WHAT 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