Disorders of Sleep

Disorders of Sleep

1. Explanations for insomnia

   • Disorder characterised by difficulty falling/maintaing sleep - not time, but how refreshed they feel after sleep
   • Primary insomnia - insomnia not caused by another health condition
     • Idiopathic insomnia - occurs at a young age, normally for life
       • Brain abnormality controlling sleep/wake cycle
     • Sleep State misperception - thinks they've slept for less than they really have
       • Dement - insomniacs overestimated time taken to fall asleep x4
       • Due to cognitive distortions in thinking
         • Zammit et al - cognitive impairment - decreased concentration, memory & problem solving
     • Psychophysiological insomnia
       • Anxiety induced insomnia. Vicious cycle trying harder to sleep, not being able to
       • Dauvillers - 72.7% primary insomniacs had familial insomnia issues, compared to 24.1% control
       • Hyperarousal of the brain makes falling asleep difficult
   • Secondary insomnia - insomnia due to an existing issue, i.e medication, psychiatric condition or environmental problems
     • Parasomnias
       • Sleep aponea - temporary inability to breathe. CO2 builds up in blood, sensed by chemoreceptors which wakes you up
         • Asthma may increase risk
       • Restless leg syndrome - uncontrollable urge to move legs, causing extended wakefulness - dopamine release thought to effect muscles
         • Possible causes: anemia & kidney failure
     • Melatonin levels drop with age - very little production by 60
     • Depression can often cause insomnia
       • Lichtein et al - Depression must precede insomnia to show secondary causality
   • PER3 - clock gene, influences sleep characteristics
     • Riemann et al - imbalances in brainstem network can be inherited
   • Zammit et al - tiredness causes ~ 1,500 road traffic deaths a year
   • Breslau et al - increased risk of drug & alcohol abuse
   • Spielman & Glovinsky - genetic factors predispose you, environmental factors bring about insomnia. Diathesis stress
     • Expectations of sleep problems can itself bring on insomnia - self-fulfilling prophecy
   • Morin et al - women diagnosed with insomnia more than men
   • Difficult to isolate factors in research, often multifactorial causes of insomnia - hard to conduct meaningful research
     • Dement - insomnia is not a sleep disorder, it is a symptom of several factors
   • Attribution therapy gets individuals to think differently about the causes of their insomnia
   • Getting insomniacs to fall asleep in front of the TV an effective method of increasing sleep

2. Other sleep disorders

   • Narcolepsy
     • Lehrmann & Weiss - sudden attacks disguise sexual fantasies
       • Lacks scientific credibility - not recognised
     • Antibodies attack & destroy body cells that produce hypocretin - low levels
       • Hypocretin can be used in treatment, or normal cells can be transplanted
       • HLA variant (autoimmune response) common in narcoleptics
         • Not in all cases
         • Lin et al - mutant gene on chromosome 12 of dogs affecting HLA production. Also found in humans
         • Mignot - narcolepsy not an inherited disorder - not in MZ twins
           • Brain injury, diet or stress possible factors
     • Malfunction of REM system narcoleptics match REM sleep characteristics - paralysis, hallucinations (daytime REM sleep)
       • Vogel - REM patterns beginning of a narcoleptic episode
         • Siegel - same brain activity in a narcoleptic dog during an attack as in REM sleep
       • There is generally little support
   • Sleep walking
     • Sleep walker is asleep but engaged in conscious actions
     • EEG shows delta waves (SWS) and beta waves (consciousness) present
       • Awakened by arousal is incomplete
       • Usually in stages 3/4 - deepest sleep
       • 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.
     • Most common in children but can suffer at any age
       • Most tend to outgrow behaviour at puberty
       • May be more common in children due to increase nREM sleep
       • Oliviero - motor activity in SWS isn't fully developed in children
     • Bassetti - 50% sleepwalking patients had HLA variant (HLA DQB1*5) compared to 24% in a control. May be a possible genetic link
       • Lecendreux et al - 50% concordance in MZ twins, 15% DZ
       • Broughton - 10x more prevalent in first degree relatives, compared to population
     • Zadre et al - Sleep deprivation led to an increase in sleep walking between 50%-90% - diathesis stress
       • Individual differences