eval circadian rhythms Flashcards
Shifting the school day
A number of researchers (e.g. Wolfson and Carskadon 1998) recommend that the school day start a couple of hours later to fit in with the typical teenage chronotype (sleep pattern). Many teenagers prefer to remain awake until the early hours and would rather ‘sleep in’ until around 10 am. Hormonal shifts in the teenage body mean that getting to sleep becomes more difficult and therefore adolescent students tend to be rather sleepy at the start of the school day. This is bound to impact upon their performance at school in the morning, and possibly throughout the day if they are sleep-deprived. Research has shown benefits for academic and behavioural performance when lessons start later in the day, including reduced dependence on caffeine (Adolescent Sleep Working Group 2014).
However, shifting the start of the day is disruptive for parents and teachers, and it limits the number of extra-curricular activities after school. Twilight hours means after-school sports, for instance, are difficult to run, and teachers are unlikely to want to remain at school until early evening as this will impact upon their family life and preparation time for school. It also would not fit in with the work patterns of parents, as most adult still work from 9 to 5. Also, critics of the proposal suggest that a later school day would not actually reduce sleep deprivation, it would simply mean that teenagers would stay up later and still be exhausted!
This suggests that even though a later start to the school day may produce a range of benefits, it is not always a practical alternative, especially for younger teens who rely on working parents to get them to school.
Shift work
One strength of research into circadian rhythms is that it provides an understanding of the adverse consequences that occur when they are disrupted (desynchronisation).
For example, 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 (Bolvin et ol. 1996). Research has also pointed to a relationship between shift work and poor health - shift workers are three times more likely to develop heart disease than people who work more typical work patterns (Knutsson 2003).
This shows that research into the sleep/wake cycle may have real-world economic implications in terms of how best to manage worker productivity.
Counterpoint
However, studies investigating the effects of shift work tend to use correlational methods. This means it is difficult to establish whether. desynchronisation of the sleep/wake cycle is actually a cause of negative effects.
There may be other factors. For example, Charlene Solomon (1993) concluded that high divorce rates in shift workers might be due to the strain of deprived sleep and other influences such as missing out on important family events.
This suggests that it may not be biological factors that create the adverse consequences associated with shift work.
Medical treatment
Another strength of research into circadian rhythms is that it has been used to improve medical treatments.
Circadian rhythms co-ordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels. These rise and fall during the course of a day which has led to the field of chronotherapeutics - how medical treatment can be administered in a way thathdiresponds to a person’s biological rhythms. For example aspirin as a treatment for heart attacks is most effective if taken last thing at night.
Aspirin reduces blood platelet activity and this can reduce the risk of heart attack.
Heart attacks are most likely to occur early in the morning, so the timing of taking aspirin matters. Research has supported this (e.g. Bonten et ol. 2015).
This shows that circadian rhythm research can help increase the effectiveness of drug treatments.
Individual differences
One limitation of research into circadian rhythms is that generalisations are difficult to make.
The studies described on the facing page (Aschoff and Wever, and Siffre) are based on very small samples of participants (just one in the case of Siffre). It seems that sleep/wake cycles may vary widely from person to person. Research by Charles Czeisler et al. (1999) found individual differences in sleep/wake cycles varying from 13 to 65 hours. In addition, a study by Jeanne Duffy et al. (2001) revealed that some people have a natural preference for going to bed early and rising early (known as larks) whereas others prefer the opposite (owls). Even Siffre, in a later 1999 study, observed that his own sleep/wake cycle had slowed down since he was a young man.
This means that it is difficult to use the research data to discuss anything more than averages, which may be meaningless.
