Biological Rhythms and Sleep AQA PSYA3

AQA Psychology A2 Unit 3 PSYA3 - Biological Rhythms and Sleep

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PSYA3 AQA psychology: biological rhythms and sleep
Endogenous pacemakers ­ internal biological body clocks
Exogenous zietgebers ­ external cues from environment
Circadian Rhythms - 24 hours
Sleep-wake cycle:
Obvious driving force behind this is daylight and awareness of the time through clock
Investigate what happens when a person is free from external cues
This allows the biological rhythm to be free running so we can see if it is the external cues
which dictate it
Michel Siffre showed that free-running cycle settles down to a regular rhythm which is little
more than 24 hours
Supported by Aschoff and Wever who placed participants in underground bunker resulting
in the absence of environmental and social time cues
Most participants displayed circadian rhythm between 24-5 hours
Some were 29 but viewed as anomalies
Shows that this circadian rhythms is directed by an endogenous `clock' ­ however clock
wasn't accurate and varied from day to day which is why exogenous cues are important
Folkard et al did an experiment to see if external cues could override internal clock
12 people in a cave for three weeks and agreed to go to bed when clock said 11.45pm and
get up at 7.45am
Gradually clock was quickened so that clock showed 24 hours passing when only 22 had
24 hour rhythm persisted ­ only one participant's rhythm matched 22 hour
Temporal isolation study: Siffre's research is a case study as was him alone and therefore it
may be his unique features cannot use to generalise
Also extraneous variables such as he was in a cave and perhaps there is a connection
between the cold in the cave and his cycle which he didn't take into consideration
But subsequent studies confirmed the findings
Research methodology
Early research underestimated the effect of artificial light and only isolated participants from
natural light, clocks and radios etc
Czeisler et al altered rhythms to 22 hours and 28 hours with artificial dim light
Campbell and Murphy shifted the rhythm with light at back of knees
Individual differences
Czeisler et al Cycle length can vary from 13 to 65 hours in different people Individuals
innately different in terms of when their rhythm reaches its peak
Duffy morning people prefer to ruse early and go to bed early and vice versa showing
Individuals will have their own cycles and has to be taken into consideration with research

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PSYA3 AQA psychology: biological rhythms and sleep
These studies follow the biological approach in understanding behaviour
Human behaviour the is result of hormones and brain activities
We are more complex than that and can override biological determinism through choices
BUT study of blind man with circadian rhythm of 24.…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Electroencephalograph (EEG)
Sleep stages:
Daily cycles of awake/sleep time follow a circadian rhythm but when asleep the body follows
an ultradian rhythm
The stages of sleep are comprised of 4 stages of NREM and the fifth REM
REM = Rapid Eye Movement which lasts 15 minutes
During REM one will experience movement of the eye beneath closed lids
Each cycle will last 90 minutes
Stage 1 NREM
Stage 2 NREM
Stage 3 NREM
Stage 4 NREM
Stage 5…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Suggests synchronisation of menstrual cycles can be effected by pheromones
Pheromones act like hormones but effect bodies of others
Free will vs determinism and the biological approach
Psychological disorders arise from Infradian rhythms such as PMS and SAD
PMS has been used in legal defence ­ Ms English drove her car into her married lover after
an argument and killed him
Charged with murder but placed on probation as argued that her actions were due to sever…read more

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PSYA3 AQA psychology: biological rhythms and sleep
These internal pacemakers are innate, inherited, genetic mechanism
2 key structures in the brain
o Suprachiasmatic nucleus (SCN)
o Pineal gland
SCN is a tiny cluster of nerve cells located in the hypothalamus
SCN obtains information about levels of light from eye via optic nerve
Stephan and Zucker did a controlled scientific experiment to see the effect of damaging
SCN on circadian rhythms
Rats in a lab exposed to 12 hours of light and 12 hours of dark…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Before electricity people's activities were dictated by the light however now there is
The most dramatic effects seen when we challenge our inbuilt clocks by changing external
zietgebers more rapidly than they are used to
See in shift work ­ traditional rotation was backward rotating
Most s/workers operating machinery or making decisions at times when their body clocks
are out of synch with external world especially the light/dark cycle
Effects of shift work
Sleep deprivation is an…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Czeisler introduced a forward shift rotation and increasing the time spent on each shift to 21
days allowing the body to adjust properly
They found after 9 months workers reported feeling less stressed, fewer health problems
and managers reported higher productivity
High mundane realism ­ field experiment not laboratory and therefore can be generalised
Finding of these studies have been supported by Gordon et al who reconstructed the
experiment in Philadelphia in the police force
Changing shifts from…read more

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PSYA3 AQA psychology: biological rhythms and sleep
They looked at the animals in their natural habitat so there will be a high ecological validity
However they had to take out to measure REM of EEG which may ruin it slightly
Lifespan changes in sleep
Function of sleep changes for the different ages causing the amount of sleep necessary to
Babies will sleep for 16-20 hours a day with 50% being REM sleep
Premature babies born at 30 weeks will may experience up to…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Physiological changes in old people result in reduced sleep for the old which can be
experienced in terms of problems with staying asleep such as apnoea or illness
Reduction of deep sleep at old age reduces the production of growth hormones explaining
some of the symptoms associated with old age ­ bone density, lack of energy
Issues debates and approaches
Cultural differences ­ many studies have shown that social factors which are different in
many different cultures have…read more

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PSYA3 AQA psychology: biological rhythms and sleep
Siegel and Rogawski suggest that REM sleep allows for a break in neurotransmitter release
which will allow for a break in neurotransmitter release
This permits neurons to regain their sensitivity and allows the body to function properly
Support for this comes from anti-depressants such as MAOI which aims to increase the levels
of neurotransmitters of the monoamine group ­ dopamine and serotonin
Side effect is that MAOIs abolish REM activity completely
This is linked to the monoamines meanings…read more



Found this really helpful thanks! :3

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