PSY2061 Lecture Notes - Lecture 12: Cataplexy, Muscle Tone, Circadian Clock
5 Jun 2018
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PSY2061 – lecture – week 12 – sleep, dreaming and circadian rhythms
• over a lifetime - sleep = 175,000 hours
• the cumulative effect of sleep loss and sleep disorder represents an under
recognised public health problem
•
o health consequences
o
▪ increased risk of hypertension, diabetes, obesity,
depression, heart attack and stroke
• why and when do we sleep?
•
o recuperation - homeostatic theories
o
▪ being awake disrupts your body’s homeostasis - sleep acts
to restore it
▪ sleep fixes the damage/dysregulation that accumulates
when we are awake
o adaptation - circadian theories
o
▪ focus on when we sleep
▪ sleep is the result of an internal timing mechanism -
programmed to sleep at night
▪ evolved to protect us from the dangers of night - e.g.
predators
▪ sleep keeps us out of trouble and conserves energy
• sleep in mammalian species
•
o serves some important physiological function
o similar to sleep of humans
• four areas of the brain involved in sleep
•
o two areas of the brainstem
o
▪ isolated forebrain - cerveau isole
▪
▪ resulting in continuous SWS
▪ encephale isole - isolated brain
▪
▪ resulting in normal sleep cycle
o two areas of the hypothalamus
o
▪ posterior hypothesis and the anterior hypothalamus were
related to excessive sleep or inability to sleep - injury
• three standard physiological measure of sleep
•
o EEG - brainwaves
o
▪ alter wakefulness - alpha waves commence when and
individual is about to fall asleep
find more resources at oneclass.com
find more resources at oneclass.com
▪ stage 2
▪
▪ sleep spindles
▪ and K complexes
▪ stages 3
▪ and 4
▪
▪ much lower frequencies
▪ delta waves
o EOG - electrooculagram - records eye movements seen during
rapid eye movement REM sleep
o electromyogram EMG - detects loss of activity in muscles during
some sleep stages
• REM sleep and dreaming
•
o externa stimuli may be incorporated into dreams
o dreams run on real time
o sleep walking less likely to occur
o interoperation
o
▪ freud theory
▪
▪ dreams are triggered by unacceptable repressed
wishes
▪ manifest dreams
▪
▪ what we experience
▪ latent dreams - the underlying meaning g
▪ no evidence for this
▪ activation-synthesis theory
▪
▪ dreams due to cortex’s attempt to make sense of
random brain activity
• how much sleep do we need
•
o depends on individual characteristics
o approximately 7-9 hours
o habitual sleep duration is associated with daytime sleep
propensity
o
▪ the less amount of sleep you have the quicker you fall
asleep and vice versa
• circadian sleep cycles
•
o approx 24 hours
o virtually all physioligcal, biochemical and behavioural process
show some circadian rhythmicity
o zeitgebers - environmental l cues that entrain circadian cycles
• homeostatic and circadian systems
find more resources at oneclass.com
find more resources at oneclass.com
