Biological rhythms: Chronotype and effective AO2

AQA A: Unit 3 – Biological Rhythms and Sleep

Whilst learning about circadian rhythms and the endogenous pacemakers that control these cycles A2 students studying this topic will inevitably come across the idea that some people are “owls” and some are “larks”. To put this in more scientific terms the proposal is that individuals may differ in terms of their chronotype. Those described as “larks” are early risers because they experience the physiological changes associated with being most alert and awake early in the morning, whilst those described as “owls” experience this peak much later in the evening.

Are you an owl or a lark?

Radio 4’s Claudia Hammond tweeted a link to a challenge to the commonly held view that people are either owls or larks. Hammond’s article entitled “Sleep: Are you an owl or are you a lark?” (BBC future, 7th August 2012) appears under the heading “Medical Myths” and refers to research (using self report measures) suggesting that very few people are actually either “owls” or “larks” and that most people do not fall neatly into one category or the other. The article provides an accessible overview of the concept of chronotype, the genetic basis of this phenomenon and research in this area.

In the Psychology classroom

Myths about sleep

There are many myths about sleep that can be used in the classroom to engage students, reveal misconceptions and stimulate discussion about the research methods that could be used to assess whether the claims are true or not (e.g. the more sleep the better, we must have 8 hours sleep to be healthy, waking a sleep walker might kill them etc.). The common sense idea that people are either owls or larks could fit into this sort of myths and truths starter activity.

Analysing circadian rhythms

Students often struggle to analyse beyond methodological issues, such as population and ecological validity, research into the rhythms themselves. A Level textbooks usually introduce the idea of innate chronotype as commentary related to individual differences in the circadian sleep-wake cycle.

The idea that there are only two chronotypes, although not explicitly stated in the texts, is implied by the absence of discussion of other types beyond the strict “owl” or “lark”.  Students can engage with the idea that there are likely to be individual differences in the nature of our cycles and discuss the impact of these differences on behaviour, perhaps considering the determinism inherent in assuming that there is a genetic basis to the timing of the peaks and troughs in biological rhythms. Students could go on to consider that attempting to neatly reduce people to a finite number of categories or types may limit our understanding in this area.

The interaction between genetic chronotype and external time givers can also provide a line of argument for AO2. For example, research has suggested that our chronotype may influence the impact of exogenous zeitgebers, such as social cues. Students might also find it useful to consider the role of chronotype in moderating the impact of shift work on health and well-being. Obviously for this to be effective AO2 students need to have a clear point to what they are saying; simply stating that there are individual differences in an essay on circadian rhythms, endogenous pacemakers or the disruption of rhythms, and offering more research demonstrating this, is descriptive and therefore is not analysis.


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