Disorders of Sleep

Explanations for insomnia
1. Disorder characterised by difficulty falling/maintaing sleep - not time, but how refreshed they feel after sleep
2. Primary insomnia - insomnia not caused by another health condition
  1. Idiopathic insomnia - occurs at a young age, normally for life
    1. Brain abnormality controlling sleep/wake cycle
  2. Sleep State misperception - thinks they've slept for less than they really have
    1. Dement - insomniacs overestimated time taken to fall asleep x4
    2. Due to cognitive distortions in thinking
      1. Zammit et al - cognitive impairment - decreased concentration, memory & problem solving
  3. Psychophysiological insomnia
    1. Anxiety induced insomnia. Vicious cycle trying harder to sleep, not being able to
    2. Dauvillers - 72.7% primary insomniacs had familial insomnia issues, compared to 24.1% control
    3. Hyperarousal of the brain makes falling asleep difficult
3. Secondary insomnia - insomnia due to an existing issue, i.e medication, psychiatric condition or environmental problems
  1. Parasomnias
    1. Sleep aponea - temporary inability to breathe. CO2 builds up in blood, sensed by chemoreceptors which wakes you up
      1. Asthma may increase risk
    2. Restless leg syndrome - uncontrollable urge to move legs, causing extended wakefulness - dopamine release thought to effect muscles
      1. Possible causes: anemia & kidney failure
  2. Melatonin levels drop with age - very little production by 60
  3. Depression can often cause insomnia
    1. Lichtein et al - Depression must precede insomnia to show secondary causality
4. PER3 - clock gene, influences sleep characteristics
  1. Riemann et al - imbalances in brainstem network can be inherited
5. Zammit et al - tiredness causes ~ 1,500 road traffic deaths a year
6. Breslau et al - increased risk of drug & alcohol abuse
7. Spielman & Glovinsky - genetic factors predispose you, environmental factors bring about insomnia. Diathesis stress
  1. Expectations of sleep problems can itself bring on insomnia - self-fulfilling prophecy
8. Morin et al - women diagnosed with insomnia more than men
9. Difficult to isolate factors in research, often multifactorial causes of insomnia - hard to conduct meaningful research
  1. Dement - insomnia is not a sleep disorder, it is a symptom of several factors
10. Attribution therapy gets individuals to think differently about the causes of their insomnia
11. Getting insomniacs to fall asleep in front of the TV an effective method of increasing sleep
Other sleep disorders
1. Narcolepsy
  1. Lehrmann & Weiss - sudden attacks disguise sexual fantasies
    1. Lacks scientific credibility - not recognised
  2. Antibodies attack & destroy body cells that produce hypocretin - low levels
    1. Hypocretin can be used in treatment, or normal cells can be transplanted
    2. HLA variant (autoimmune response) common in narcoleptics
      1. Not in all cases
      2. Lin et al - mutant gene on chromosome 12 of dogs affecting HLA production. Also found in humans
      3. Mignot - narcolepsy not an inherited disorder - not in MZ twins
        Brain injury, diet or stress possible factors
  3. Malfunction of REM system narcoleptics match REM sleep characteristics - paralysis, hallucinations (daytime REM sleep)
    1. Vogel - REM patterns beginning of a narcoleptic episode
      1. Siegel - same brain activity in a narcoleptic dog during an attack as in REM sleep
    2. There is generally little support
2. Sleep walking
  1. Sleep walker is asleep but engaged in conscious actions
  2. EEG shows delta waves (SWS) and beta waves (consciousness) present
    1. Awakened by arousal is incomplete
    2. Usually in stages 3/4 - deepest sleep
    3. Jules lowe - killed his father and claimed he was sleep walking. Had history of sleep walking and was never violent. Acquitted of murder. Suffering insane automatism.
  3. Most common in children but can suffer at any age
    1. Most tend to outgrow behaviour at puberty
    2. May be more common in children due to increase nREM sleep
    3. Oliviero - motor activity in SWS isn't fully developed in children
  4. Bassetti - 50% sleepwalking patients had HLA variant (HLA DQB1*5) compared to 24% in a control. May be a possible genetic link
    1. Lecendreux et al - 50% concordance in MZ twins, 15% DZ
    2. Broughton - 10x more prevalent in first degree relatives, compared to population
  5. Zadre et al - Sleep deprivation led to an increase in sleep walking between 50%-90% - diathesis stress
    1. Individual differences

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Disorders of Sleep

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