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Sleep - Coggle Diagram
Sleep
Behavioural effects
Sleepwalking
Happens mainly in deep sleep and occurs when the blockade that prevents motor impulses is lifted, but the other sleep mechanisms remain
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If dreams involve talking and listening, regions of the brain involved in speaking and listening become active
Lucid dreaming
Occurs when the frontal lobes 'wake up' during sleep, but the block on incoming and outgoing signals continues
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Circadian rhythm
Patterns of behavioural, biochemical or physiological fluctuation that has a 24 hr period
Zeitgebers
Environmental cue like light and dark determine our circadian rhythm and are able to lengthen or shorten circadian cycles
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Jet lag
Occurs when the zeitgebers are accelerated during an east-bound flight ad decelerated during a west-bound flight
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Insomnia
Inability to obtain sufficient amount of sleep to feel rested and can be characterised by difficulty falling or staying asleep
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Cataplexy
Recurring losses of muscle tone during wakefulness, triggered by an emotional experience
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Parasomnia
Involve unconscious complex, semi-purposeful, and goal-directed behaviour that have meaning or importance to the individual
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Cycles
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Non-REM sleep (NREM)
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4 stages
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Stage 2
Irregular stage that contains periods of theta activity and is defined by bursts of regular 14 to 18 Hz EEG waves as well as sharp negative EEG potentials
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Stage 3
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When entering this stage, extremely slow brain delta waves are replaced by smaller and faster waves.
During this period, a person may experience sleep-walking, night terrors, talking during sleep.
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Slow-wave sleep
Non-REM sleep, characterised by synchornised EEG activity during it's deeper stages of sleep
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Beta activity
EEG in wakefulness, comprising a mix of many different high frequencies with low amplitutude
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Alpha rhythm
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It consists of regular, medium frequency waves.
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REM
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Rate of cerebral flow in human brains is high in the visual association cortex but low in the primary visual cortex and the prefrontal cortex
Sleep deprivation
REM rebound
Following REM sleep deprivation, more than usual amount of REM in the following night
The more REM-sleep deprivation, the higher the tendency to fall into REM
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Microsleep
Brief periods of sleep, typically about 2-3 seconds long, during which the eyelids drop and the subject becomes less responsive to external stimuli, although they're still standing
Brain areas
Polysomnography
System of sleep assessment using EEG, EMG and EOG
While we are in SWS, the hippocampus sends the information to our frontal cortex.
Since the infromation is compressed, our dreams are more static, involving older memories and are emotionally charged
When we transition to REM sleep, our hippocampus is shut down to allow the frontal cortex to process new information
REM is the time when the most vivid dreams occur, because the brain is so active during this stage
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Retinal ganglion cell
Neurons in the eye that send signals to the brain, to inform whether it is day or night via retinohypothalamic pathways to the SCN
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The ability to remain in a stable period of sleep or wakefulness is a result of reciprocal inhibition between the wake-promoting neurons and the sleep-promoting nucleus
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Theories
Homeostatic factors
If we don't sleep for a long time, we get sleepy
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Adaptation theory
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Sleep does not serve any specific function, just an adaptation to our internal circadian rhythmic clocks which are programmed to sleep regardless
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