Biological Rhythms and Sleep
DISORDERS OF SLEEP
(1) Insomnia
(2) Sleepwalking
(3) Narcolepsy
Syllabus
Biological Rhythms
• Circadian, infradian, and ultradian rhthyms,
including the role of endogenous
pacemakers and of exogenous zeitgebers in the
control of circadian rhythms
• Disruption of biological rhythms, for example shift
work, jet lag
Sleep
• The nature of sleep including stages of sleep and
lifespan changes in sleep
• Functions of sleep, including evolutionary and
restoration explanations
Disorders of Sleep
• Explanations for sleep disorders, including
insomnia, sleep walking and
narcolepsy
You must be able to…
• You MUST be able to
• Briefly outline each disorder
• DISCUSS at least one explanation for each
disorder
• NB. All explanations revolve around
biological and psychodynamic theories so
USE THE SAME EVALUATION POINTS (but
apply them appropriately)
Look, you know this stuff…
• Three disorders – Insomnia, Sleep Walking, Narcolepsy
• Biological – Genetic
– Higher concordance for the disorders across MZ twins suggests a genetic
component
• Biological – Neural (SCN, Pineal Gland, Melatonin, Hypocretin)
– Insomnia and Narcolepsy – when the endogenous aspects which influence
sleep/wake are abnormal
– Sleep Walking – Underdeveloped / abnormal neural structures which
influence sleep, especially those which lead to paralysis
• Psychodynamic
– Early trauma -> Unconscious Conflicts -> abnormal behaviours to overcome /
escape from / revert to a time before trauma
Discuss explanations for INSOMNIA (8+16)
• What is Insomnia
– A common dyssomnia
– Different durations (Transient, Short Term,
Chronic)
– Different Types: PRIMARY vs SECONDARY
Discuss explanations for INSOMNIA (8+16)
DESYNCHRONISATION
• Insomnia a result of EPs
becoming desynchronised
with new EZs
• EVALUATION
– Can only explain transient and
short term insomnia as EPs will
resynchronise after a few days
– Doesn’t take into account
individual differences; some
people do not experience
insomnia when experiencing
new EZs
PERSONALITY FACTORS
• People with a Neurotic
Personality are likely to
suffer from insomnia
– Paranoia, excessive thoughts,
etc
• EVALUATION
– Incomplete
Discuss explanations for INSOMNIA (8+16)
• BIOLOGICAL FACTORS
• Hyperarousal – Brain scans of Insomniacs show increased neural activity
in the hypothalamus and PFC. Makes sense as these areas contain key
structures which influence sleep.
• Abnormal SCN - does not instruct the pineal gland to produce
MELATONIN therefore a person will not fall asleep
• Abnormal brain chemistry – Post mortums of insomniacs indicate a
reduction of GABA / GABA receptors. Makes sense as GABA is an
inhibitory neurotransmitter [GABA especially inhibits motor activity] so
low levels will lead to an inability to ‘switch off’
• Genetic Abnormalities – some evidence for genetics
– Beaulieu-Bonneau – 35% of insomniacs had a first degree relative who
suffered the disorder
– Watson – 0.47 concordance for insomnia across MZ twins, 0.15 between DZ
twins).
– NB. Never 100% concordance; indicates that environmental factors must be
involved
Discuss explanations for INSOMNIA (8+16)
• BIOLOGICAL FACTORS – Evaluation
• OBJECTIVE, TESTABLE, FALSIFIABLE – EVIDENCE,
• But METHODOLOGICAL ISSUES with evidence
– Correlational nature
– Problems with post mortems
• OVERLY DETERMINISTIC AND INCOMPLETE;
– There are insomniacs who do not posses any of the biological abnormalities
specified previously but who still suffer from the disorder
– need to take into account other factors (e.g. personality traits such as
neuroticism) and take an IDIOGRAPHIC approach
– Diathesis – Stress?
• CAUSE AND EFFECT ISSUES – Insomnia may be an effect of an underlying
disorder (e.g. sleep apnoea). Important to take this into account as there
are major treatment implications
Discuss explanations for SLEEP WALKING (8+16)
• What is SLEEP WALKING?
– A PARASOMNIA
– Does not result in day time sleepiness
– Sleep walkers can carry out many, sometimes
complicated, tasks (e.g. driving a car)
Discuss explanations for SLEEP WALKING (8+16)
PSYCHODYNAMIC explanation
• SW is an expression of
unresolved unconscious
conflicts
• SW is when a person ‘acts out’
repressed traumas and
anxieties, which ‘spill into’
NREM
• May represent a desire to
sleep where a person slept as
a child; sleepwalker is trying to
‘get back’ to a place associated
with low anxiety
EVALUATION
• UNFALSIFIABLE and based
on ABSTRACT CONCEPTS
– Making it unscientific and
difficult to test / prove
• SUBJECTIVE
• INCOMPLETE
Discuss explanations for SLEEP WALKING (8+16)
BIOLOGICAL
•
NEURAL – Post Mortems of Sleep
Walkers show underdeveloped neural
mechanisms, especially those which
inhibit movement during sleep (e.g.
GABA structures underdeveloped /
abnormal as these inhibit motor
movements [sleep paralysis])
–
•
Explains why sleepwalking is most
common in children
GENETIC – Some evidence for role of
genetics (higher concordance between
MZ twins than DZ twins – Bakwin),
especially abnormality of the HLA Gene
(BASSETTI -50% of SW had a HLA
abormality)
–
But not 100% so environmental factors
must be involved
EVALUATION
• OBJECTIVE, TESTABLE and
FALSIFIABLE HYPOTHESES
• Problems with research
• OVERLY DETERMINISTIC and
INCOMPLETE
• TOO SIMPLISTIC:
– DIATHESIS – STRESS approach
the most complete
explanation…
Discuss explanations for NARCOLEPSY (8+16)
• What is NARCOLEPSY?
– A DYSSOMNIA
– Rare: 1 in 2000
– May be accompanied by CATAPLEXY (loss of
muscle tone), HYPNOGOGIC HALLUCINATIONS
(dreamlike experiences), SLEEP PARALYSIS
Discuss explanations for NARCOLEPSY (8+16)
GENETIC
• Narcolepsy may be caused by
inherited genetic
abnormalities
• Evidence from SELECTIVE
BREEDING studies with DOGS
• Lin = Chromosome 12? Makes
sense as this is responsible for
regulating HYPOCRETIN
(which regulates arousal and
wakefulness)
EVALUATION
• EXTRAPOLATION ISSUES
(the genetic abnormality
seen in the dogs does not
apply to humans)
• INCOMPLETE – narcolepsy
DOES NOT APPEAR TO RUN
IN FAMILIES! Other factors
must be more influential
Discuss explanations for NARCOLEPSY (8+16)
NEURAL
EVALUATION
•
• EVIDENCE – Post mortem studies
show narcoleptics had low levels
of hypocretin producing cells
• But there are CAUSE AND EFFECT
ISSUES with this research
• However, further support is
offered by observation of DRUG
use (e.g. amphetamines found to
reduce narcolepsy and these
influence hypocretin)
•
•
•
Narcolepsy caused by abnormalities
with the structure / function of the
hypothalamus
Makes sense as the hypothalamus
contains key sleep structures such as
the SCN
In narcoleptics, the SCN may be
instructing the pineal gland to produce
melatonin at random times, thus
making the person uncontrollably fall
asleep
Also hypothalamus regulates
HYPOCRETIN (see previous slide) and
GABA production [which inhibits motor
movement – explains the cataplexy
associated with narcolepsy]
• DETERMINISTIC and INCOMPLETE
• TOO SIMPLISTIC INTERACTIONIST approach the
most complete
Discuss explanations for NARCOLEPSY (8+16)
PSYCHODYNAMIC
• Narcolepsy is a defence
mechanism employed by
the Ego to allow a person an
escape from trauma and
anxiety
• Makes sense as narcolepsy
is often triggered in high
anxiety / emotion causing
situations
• Maladaptive EGO may stem
from early trauma
EVALUATION
• ABSTRACT and
UNFALSIFIABLE
• TOO SIMPLISTIC – ignores
the role of biological factors
• INCOMPLETE
• INTERACTIONIST THEORY
the most complete?