Biological Rhythms: The Circadian Rhythm Essay Plan

Here's an essay plan on the subject of biological rhythms: The Circadian Rhythm. Use it if you want, I chose these studies/explanations as they had the most information to write about. When writing essays in psych remember about breadth and dept, 200 words approx for AO1 and 400 approx for AO2/3.

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  • Created on: 23-01-10 21:22
Preview of Biological Rhythms: The Circadian Rhythm Essay Plan

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Biological Rhythms: The Circadian Rhythm Essay Plan
1. Describe in detail the sleep wake cycle- Siffre- self study living in caves- 61 days in the Alps-
resurfaced 17th September but thought the date was the 20th August, second example
Texan cave, his natural circadian rhythm settled down to just over 24 hours, but this could
change to as much as 48 hours. Aschoff and Weaver- participants placed in a WWII bunker in
the absence of environmental and social time cues. They found that most people displayed
circadian rhythms between 24 and 25 hours, but some rhythms were as long as 29 hours.
Folkard looked at whether external cues could override the internal clock, group of 12
people lived in a cave for three weeks, went to bed when the clock said 11:45pm and get up
when it said 7:45am, clock went normally initially then quickened to just 22 hours. Found at
the start their circadian cycle matched the clock, as it quickened they didn't match and
continued to follow a 24 hour cycle.
2. Describe core body temperature- lowest at 4:30 am (36°c) and highest about 6pm (38°c),
slight dip just after lunch- bi-daily. Hormones- lowest at midnight and peaks about 6am,
makes you awake/alert, melatonin (stimulates sleep) and growth hormone both peak about
3. Critical Point 1: There is a methodological flaw in the evidence to support the sleep-wake
cycle especially carried out by Siffre. This type of research is an example of a case study,
therefore it can be difficult to generalise his behaviour just based on the results that his body
gave. Also as he was living in a cave his body could give particular effects, due to the fact
that it is cold. However, Siffre's study was an experiment because of he controlled the
exogenous zeitgebers to observe the effects of the sleep wake cycle. Consequently, this
type of research is important because it allows us to draw casual links between the two
4. Critical Point 2: There is another flaw in this research, because although they were eliminated
from variables that might affect their circadian rhythms, they were not isolated from artificial
light because it was thought that dim light, instead of daylight would not affect the circadian
rhythms. Czeisler altered participants' circadian rhythms down to 22 hours and up to 28 hours
just using dim lighting. As a result of this, this proves that dim lighting needs to be taken into
account when looking whether exogenous zeitgebers affect the circadian rhythms.
5. Critical Point 3: Also there are individual differences to take in account. Czeisler found that
people's circadian cycles can vary from 13 to 65 hours. Therefore, it can be difficult to
generalise the results to all humans. Proving the idea about our sleep wake cycles averaging
about 24 hours false. The second individual difference is about when individuals circadian
rhythms' reach their peak. Duffy found that morning people prefer to rise early and go to
bed early unlike evening people who prefer to wake and go to bed later. Consequently, this
disproves the timings for the sleep-wake cycle once again.
6. Critical Point 4: There is evidence to support the argument about core-body temperatures
being linked with levels of concentration. Folkard found that the afternoon group (higher
core body temperature) displayed superior recall and comprehension retaining about 8%
more meaningful material. This therefore implies that long term recall is best when core body
temperature is highest. Also Gupta found that performance on IQ tests were best at 7pm as
compared to 9am or 2pm. Therefore, this factor should be taken into consideration when
taking examinations. However, IQ tests can be seen as culturally biased, and the exercises
not relevant to real life situations.


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