AQA Psychology for A Level Year 2 - Student Bk

1. With reference to an example, define what is meant by a circadian rhythm . [3 marks] 2. Describe one study that investigated a circadian rhythm. [4 marks] 3. Discuss research into circadian rhythms. Refer to evidence in your answer. [16 marks] Check It Poor control in studies Although participants in the studies on the facing page were deprived of natural light, they still had access to artificial light. For instance, Siffre turned on a lamp every time he woke up which remained on until he went to bed. It was assumed by him and others that artificial light, unlike daylight, would have no effect on the free-running biological rhythm. However, in tests, Charles Czeisler et al . (1999) were able to adjust participants’ circadian rhythms from 22 to 28 hours using dim lighting. As such, the use of a light may be analogous to participants taking a drug that resets their biological clock. Consider: Explain why the use of artificial light in the cave and bunker studies may act as a confounding variable . Individual differences One further issue which complicates the generalisation of findings from studies of the sleep/wake cycle is that individual cycles can vary, in some cases from 13 to 65 hours (Czeisler et al . 1999). In addition, a study by Jeanne Duffy et al . (2001) revealed that some people display a natural preference for going to bed early and rising early (known as ‘larks’) whereas some people prefer to do the opposite (‘owls’). There are also age differences in sleep/wake patterns (see the Apply-it above right). Consider: Why are these individual differences (and the use of case studies mentioned above) a problem for research into the sleep/wake cycle? Evaluation e X tra Evaluation Practical application to shift work Knowledge of circadian rhythms has given researchers a better understanding of the adverse consequences that can occur as a result of their disruption (known as desynchronisation ). For instance, night workers engaged in shift work experience a period of reduced concentration around 6 in the morning (a circadian trough ) meaning mistakes and accidents are more likely (Boivin et al . 1996). Research has also suggested a relationship between shift work and poor health: shift workers are three times more likely to develop heart disease (Knutsson 2003) which may in part due to the stress of adjusting to different sleep/wake patterns and the lack of poor quality sleep during the day. Thus, research into the sleep/wake cycle may have economic implications in terms of how best to manage worker productivity. Practical application to drug treatments Circadian rhythms co-ordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels. This in turn has an effect on pharmacokinetics , that is, the action of drugs on the body and how well they are absorbed and distributed. Research into circadian rhythms has revealed that there are certain peak times during the day or night when drugs are likely to be at their most effective. This has led to the development of guidelines to do with the timing of drug dosing for a whole range of medications including anticancer, cardiovascular, respiratory, anti-ulcer and anti-epileptic drugs (Baraldo 2008). Use of case studies and small samples Studies of the sleep/wake cycle tend to involve small groups of participants, as in the experiment by Aschoff and Wever, or studies of single individuals, as in the case of Siffre. The people involved may not be representative of the wider population and this limits the extent to which meaningful generalisations can be made. In his most recent cave experience in 1999, Siffre observed, at the age of 60, that his internal clock ticked much more slowly than when he was a young man. This illustrates the fact that, even when the same person is involved, there are factors that vary which may prevent general conclusions being drawn. Concepts: The teenage circadian rhythm A £700,000 project, involving 106 schools will give 32,000 14–16-year- olds the chance of a lie-in and a later start to the school day to assess the impact on their educational achievement. According to neuroscientists, teenagers’ circadian rhythms typically begin two hours after those of adults, so current school start times mean they wake up too early and are trying to focus when their body still needs sleep. It also means, at bed time, they tend not to be as tired as they should be. A pilot study was run at Monkseaton High School in North Tyneside in 2010. Dr Paul Kelley, who now works as a research associate at Oxford University’s Sleep and Circadian Neuroscience Institute, which is leading the new project, was headteacher at the time. After a decade of researching all the available evidence, he decided to put the start of the school day back to 10am over a two-year period. ‘There were very positive outcomes, both academic and in terms of health’, said Kelley. ‘Academic results went up, illness down and the atmosphere in school changed. The students were much nicer to each other, it was bliss.’ Question What evidence is there that the sleep/wake cycle may vary due to individual differences? @ookx hs @ookx hs Methods: Meta-analysis A researcher conducted a meta-analysis of studies that investigated the length of the sleep/wake cycle. As a result of the meta-analysis, the researcher concluded that the average length of the sleep/wake cycle is between 24 and 25 hours. Questions 1. Explain what is meant by a meta-analysis. Refer to this investigation in your answer. ( 2 marks ) 2. Outline one strength and one limitation of conducting a meta- analysis. Refer to this investigation in your answer. ( 4 marks ) 3. Briefly discuss the implications of psychological research for the economy. Refer to this investigation in your answer. ( 4 marks ) 4. The studies of the sleep/wake cycle the researcher analysed were from a number of neuroscience journals and had all been through a process of peer review . Outline and briefly discuss the role of peer review in psychological research. ( 8 marks ) @ookx hs @ookx hs Exhausted? It’s your age, mate . . . Biological rhythms: Circadian rhythms 47 •