Circadian Rhythm Evaluation

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Evaluate research into Circadian rhythms (16 marks) One of the main issues with research in to Circadian rhythms is the fact the some of the early research has admitted to being flawed when estimating the time length of a free running cycle with in the body. These flaws are likely to be to do with the methods used to estimate the amount of time that these cycles ran for; therefor meaning these methodological issues could affect the generalizability of any results found from the early studies. To explore the effects of circadian rhythms experimenters used case studies and self-report methods. Because of these small samples in the case studies and the possibility of falsified information from the self-report studies this brings methodological issues in to play. These issues could affect the external validity of the results –the results could be valid within the study but (high internal validity) but outside the study they are not- this means the results are harder to generalise to the target population. In all studies carried out in to circadian rhythms participants were removed from all obvious extraneous variables that could affect the running time of their circadian rhythm however they were not removed from artificial light. This could cause problems for the results found because Czeisler found that he could manipulate the participant’s circadian rhythms down to 22 hours and up to 28 hours using dim artificial light alone. This ability to manipulate the participant’s rhythms means the studies would then lack internal validity because even within the study results are not valid. On the other hand of the pervious evaluation point, not allowing participant’s to have artificial light during the experiments means that they are trapped in a dark cave or place for as long as six months. During this time the participant could be at risk of participant harm and there
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