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Circadian Rhythms Evaluation - Coggle Diagram
Circadian Rhythms Evaluation
Weakness
There are individual differences.
Cycle length can vary from 13-65 hours = Czeisler et al.
When rhythms reach peaks it was found that ‘mornung’ people prefers to rise early and go to bed early. ‘Evening people’ preder to wake and go to bed later.
There may be innate individual differences in circadian rhythms —-} Researchers should focus on these differences during investigations.
Research methodology
Early studies isolated participants from variables that may affect circadian rhythms - clocks, radios and daylight.,
But not isolated from artificial light because it was assumed this would not affect circadian rhythms.
However…
CZEISLER ET AL 1999
Used artificial film light to alter circadian rhythms to 22 hours or 28 hours.
Strength
There is research to support the interaction between endogenous pacemakers and exogenous zeitgebers in the control of circadian rhythms.
Example
Aschoff and Weber 1976
They placed participants in an underground WWII bunker with artificial light but no natural light and a complete lack of environmental and social cues.
They found that most participants soon settled into a sleep/wake cycle of between 24 and 25 hours, although some rhythms were as long as 29 hours.
Weakness
There are a number of problems with this research:
Lots of the research carried out into the control of circadian rhythms can be criticised for being case studies
Example
David Lafferty and Michel Siffre have carried out isolation studies (involving only themselves) in an attempt to investigate the control of circadian rhythms in relations to EPs and EZs.
This is a weakness because, the evidence is based on only a select few individuals, this means that population validity is low and therefore there are difficulties when it comes to generalising the finings to the whole population.
Weakness
Much of the research looking at the control of circadian rhythms can be criticised as being androcentric.
Example
For example, research from Siffre and David Lafferty are only looking at the control of circadian rhythms from a male perspective (i.e. they use male participants).
This is a weakness because the findings from this research only tells us about the EP and EZ control of male circadian rhythms. Females are physiologically different to males (e.g. they experience different biological processes such as the menstrual cycle) and therefore, it could be the case that female sleep/wake cycles are controlled in different ways by different internal and external processes.
Temperature
Light in setting circadian rhythm
Buhr et al 2010
believed that it is actually temperature that controls the body clock.
Although light may be a trigger, SCN transforms information about light levels into neural messages that set body’s temperature.
This fluctuates on a 24 hour circadian rhythm.
Small changes can send powerful signal to our body clocks .
Buhr found that these fluctuations in temperature set the timing of cells in the body, causing tissues and organs to becomes either active or inactive,
This shows that croci and rhythms are controlled and affected by several different factors, and suggests that a more holistic approach to research might be preferable,