Sleep Disorders

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  • Sleep Disorders
    • Narcolepsy
      • Excessive sleepiness & often loss of muscle tone resulting in cataplexy (muscle paralysis). Symptoms include excessie daytime sleepiness, involuntary attacks of sleep that strike at any time, memory loss,increased heart rate, periods of alertness, hot flushes.
        • Cataplexy has been argued to be essential symptom of disorder but recently been decided that the disorder can be diagnosed without it. It may only affect muscles in the face or in severe cases cause loss of all muscle tone resulting in patients collapsing on the floor.
          • Cataplexy often accompanied by vivid hallucinations which can be frightening & difficult to distinguish from reality. SImialar to hypnogogic hall experienced on falling asleep.
        • Patient may sleep for hrs a day but night sleep is disrupted. Patients often respond as if on auto-pilot & nod off starigh into REM at the start of the night.
      • Not a psychological disorder but a neurological condition resulting in a fault in the mechanisms controlling the normal circadian sleep/wake cycle :. causing REM sleep to occur at inappropriate times.
      • Explanations include genetics and hormones.
        • Siegel et al: compared preserved brains of 4 narcoleptics, after close examination they were found to have 93% fewer hypocretin neurons than non-narcoleptics brains.
          • Hypocretin plays an important role in keeping us awake. At night production of the hormone in the hypothalamus stops to make us fall asleep.
        • Small injections of hypocretin reduce cataplexy in dogs but larger injections make it worse.
        • In dogs 1 group of genes seems to be responsible however in humans there is a high level of disconcordance in MZ twins.
      • Although hypocretin is a major contributing factor further clarification is needed of its precise role.
        • Mahowald & Schenck: report the absence of hypocretin is neither necessary nor sufficient to explain all cases of narcolepsy.
    • Insomnia
      • Problems falling asleep &/or staying asleep. Sleep that occurs tends not to be deep & is easily disturbed. Linked to fatigue, poor attention, impaired judgement, decreased performance & increased risk of accidents. Condition can turn into aggrivating cycle with patient worrying about disorder which will then result in bad quality sleep.
        • Can be looked at in terms of severity: mild, moderate, severe, acute or chronic. Mainly categorised by possible causes of it.
          • Primary Insomnia: most common, no clear cause so seems to be an illness in its wn right.A sleep problem but no psychological/ psychiatric cause. Likely to be a result of maladaptive behaviour/learning.
            • Characteristics must last for 1 month & indi must not have suffered any other sleep disorder or psychopathology to be diagnosed.
            • Explanations include psychological(learned or behavioural conditions eg classical); idiopathic (brain mechanisms being at fault);perception (perc of time passing being inaccurate). Also a fmaily link (either nature or nurture).
              • Dauvilliers et al: found 73% of insomniacs  reported a family histor of it compared to 24% of non-insomniacs. Assumption is that it is genetic however as with phobias/anxiety it could be a response to nurture.
          • Secondary Insomnia: has specific cause eg sleep apnoea, RLS, depression, anxiety, shift work, physical injuries & taking drugs.
            • Dement: states this type of insomnia should not be classified as a disorder in its own right as it is merely a sypmtom of other factors. Raises question as to whether doctors should treat sleep dis or original cause.
            • Explanations include stress, age (as we get older less sleep is needed), medical conditions (hayfever, asthma), drugs (caffeine, nicotine), and environment (hot summers night, an uncomortable be)
              • Smith et al: studied psysiological differences in the brain, found insomniacs had significantly reduced flow of blood to various areas of cerebal cortex suggesting abnormal CNS activity during REM.
              • Morin et al: investigated link with stress, found although insomniacs experienced similar numbers of stressors to control, they reported higher levels of anxiety.
                • Concluded actual stressors were not the cause. P.A. of how to treat insomnia. Dement states doctors sould suggest better coping strategies such as problem-focused techniques.
      • Complex disorder & probably an interaction of manyfactors meaning confounding factor are present in diagnosis.
      • Methodological issues with research as self report is unreliable and use of sleep labs is not an accurate perception of real life.
    • Somnabulism
      • Is a common condition but far more common in children. Sleepwalkers move quite naturally & other than a glazed expression in the eyes may appear to be awake. Usually have no recollection of the event the next morning.
        • Associated with Stages 3/4 (along with night terrors). Association with deep sleep means it usually occurs in the 1st half of the night. In severe cases more than 1 episode can occur per night.
      • Causes include incomplete arousal, genetics & tiredness.
        • EEG monitoring of sleepwalkers shows they typically have delta activity with beta activity mixed in. Researchers believe somnabulism occurs when the patient wakes from deep sleep but arousal is incomplete so as a result they are not fully woken.
        • Hublin et al: found in a study of Finnish twins a concordance of 66% fo boys & 57% for girls.
        • Bassetti: claims to have isolated a specific gene that maybe a risk factor in somnabulism. Present in 50% sleepwalkers & only 25% non-sleepwalkers. Gene is part of a group of genes associated with narcolepsy.
        • Zadra et al: tested volunteers in sleep labs. 1st night: observed found 32 sleepwalking episodes. 2nd night: kept awake. 3rd night: observed found 92 sleepwalking episodes.
          • Sample size small & volunteer, most sleepwalkers do not seek medical attention as they areunaware they have it, those that are usually more serious cases so sample is not typical cross-section of populaton.
          • Methodological issues, sleep lab not usual environment, confounding variable of 3rd night as they may have got used to surroundings.
  • Gender bias: Smith study only on women so not generalisable. Also women are more likely to report having disorder.
  • Culture bias: Hublin et al study.
  • Nature/Nurture debate: Concordance is Hublin et al study may be due to environment.
  • Focuses on Bio Approach :. reductionist. May be unknown psychological/ environmental cause.


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