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Task 7. Sleep problems (How can you measure sleep? (Polysomnographic…

- - - - Stage 2: signalled by sleep spindles or K-complexes in the EEG, follows this brief episode of stage 1 and continues for aprox. 10 to 25 minutes. A more intense stimulus is required to produce arousal. 45% of total sleep.
      - Stage 3: lasts only a few minutes in the first cycle and is transitional to stage 4 as more and more high-voltage slow-wave activity occurs. Deltha waves - deepest sleep -below 4 hz (slowest frequency but highest amplitude) 25%
      - Stage 1 : usually persists for only a few (1 to 7) minutes at the onset of sleep. It is usually discontinued during this stage and is associated with a low arousal threshold. Role in initial wake to sleep transition and it occurs as a transitional stage throughout the night. - 4-8 hz theta waves (in the transition to sleep, alpha waves 9-13 hertz) 5% of total sleep
      - Nrem sleep - lasts approx, 20-40 mins in the first cycle. An incrementally larger stimulus is usually required to produce an arousal from stage 3 or 4 sleep than from stage 1 o 2 sleep. stag 4?
- - - - From neurocognitve perspectives: high-frequency EEG is associated with increased information processing and long-term memory formation, then the patient is correctly estimating the amount of time required to disengage from the environment (p)
    - - From neurocognitve perspective: Medication decreases sleep latency and increases sleep time, the magnitude of these effects are moderate. Sleep latency is reduced by 15 minutes and total sleep time is increased by about 30 minutes. This patients overestimate this effect because of diminish ability to process information and promoting mesograde amnesia.
    - - From neurocognitive perspectives: sleep state misperception occurs as a result of high-frequency EEG related increases in information processing. Perception of perturbing environmental stimuli serves to blur the phenomenologiclal distinction between sleep and wakefulness.
    - - From neurocognitve perspective: the sleep EEG effect of hypnotics appears to be in strong contradiction to the neurocognitive model. How can the hypnotics be effective but speed up sleep EEG? they are faster than delta but slower than beta and gamma.
  - - - Classical conditioning: High frequency EEG activity is elicited in response to the visual and/or temporal cues usually associated with sleepiness and sleep, and this occur in the abscence of stressors (as oppose to acute insomnia).
      - High EEG activity: allows for increased sensory processing, information processing and formation of long-term memory This capacities should be attenuated in sleep.
      - Components of the neurocognitive model
        
        (2) High frequency EEG and Insomnia: transition from wakefulness to sleep entails a shift in the frequency spectrum of the EEG from high frequency to low frequency. Subjects with insomnia exhibit increased high frequency EEG activity prior to sleep onset, for a period to be as long as 15 min into the first NREM cycle.
        
        (3) Enhanced sensory processing: sleep onset may be directly associated with sleep initiation and/or sleep maintenance difficulties. The individual is particularly vulnerable to perturbation by environmental stimuli. This can explain one of the benefit of the benefits of sleeping pills (hypnotics may diminish sensory processing).
        
        Enhanced information processing: at around sleep-onset may be directly related to the perception of sleep and wakefulness. The perception of perturbing environmental stimuli may blur the distinction between sleep and wakefulness. (asleep but capable of information processing, trouble recognising if they were awake or asleep). For that reason, insomnia patients can judge PSG sleep was wakefulness. Hypnotic medication block sensory processing, thus the patient would be less aware of environment, and conclude being asleep.
        
        Enhanced long-term memory function: normally subjects can recall information from periods immediately prior to sleep, during sleep, or from brief arousals which occur during the night. If the ability to encode is intact in arousal, this can influence judgement of sleep onset and sleep duration => tendency to overestimate retrospectively: (1) amount of time that takes to sleep and the amount of time awake during the night. => hypotics may be able to produce amnesia.
        
        (1) Cortical arousal:high frequency EEG activity in beta and gamma is associated with cognitive function.