A03 - Circadian Rhythms

• Limitation of Circadian Rhythms - hard to generalise PART 1


  P: All research mentioned involves individual cases / small groups, making it hard to generalise studies.

  E: Studies of sleep/wake cycle use small groups of participants (e.g. Aschoff & Wever) or even single individuals (e.g. Siffre).

  E: Czeisler (1999) found variations in individuals sleep/wake cycle from between 13-65 hours. And, Duffy (2001) found some people have natural preference for going bed early & rising early (larks) but others have tendency for later bedtimes & later wake ups (Owls) - individual differences. 
• Limitations of Circadian Rhythms - Hard to generalise - PART 2


  E: Participants may not be representative of the wider population and this limits making meaningful generalisations. Siffre observed that his own individual internal clock ticked much more slowly at 60 than when he was younger.

  L: Meaning only conclusions drawn are based on average with no account for individual variations on the sleep/wake cycle. Hard to generalise. This suggests that even when the same person is involved, there are factors that may prevent general conclusions being drawn.
• Circadian Rhythms - Positive Implications - PART 1


  P: Another strength into research into circadian rhythms is real-world application has also had positive implications in the area of drug efficacy and  medical treatment.

  E: As the body goes through a circadian cycle various bodily processes and chemicals shall be altered. Circadian rhythms co-ordinate the body’s basic processes (e.g. heart rate, hormone levels) with implications for chronotherapeutics (timing medication to maximise effects on the body). 
• Circadian Rhythms - Positive Implications - PART 2


  E: Thus there are times of the day when a clinical drug will have a high effect e.g. Bonten et al (2015) found that taking aspirin is the most effective last thing at night to ensure people with heart problems are protected in the morning from hear attacks when blood pressure is at its highest.

  L: Guidelines have now been developed clearly stating timing of drug dosages to ensure maximum efficacy. Showing that circadian rhythm research can help increase the effectiveness of drug treatments.
• Circadian Rhythms - Shift Work - PART 1


  P: One strength of circadian rhythm research is application to shift work. Knowledge of circadian rhythms gives researchers a better understanding of the adverse consequences that can occur as a result of their disruption (known as desynchronisation). Knowledge beneficial in improving conditions of shift workers.

  E: Shift work creates desynchronisation of biological rhythms. Boivin et al (1996) found shift night workers experience a lapse of concentration around 6am (a circadian trough) meaning mistakes and accidents are more likely to happen.
• Circadian Rhythms - Shift Work - PART 2


  E: Research also suggests a link between shift work and poor health, with shift workers 3 times more likely to develop heart disease (Knutsson 2003) may be due in part to the stress of lack of poor quality sleep during the day.

  L: Thus research into the sleep/wake cycle may have economic implications in terms of how best to manage shift work and workers productivity. This research can help companies to lower risks involved in shifts and increase productivity.
• Circadian Rhythm - correlation not causation - PART 1


  P: Studies investigating the effects of shift work tend to be correlational.

  E: This means it is difficult to establish whether desynchronisation of the sleep/wake cycle is actually the direct cause of negative effect (desynchronisation may not be the cause of observed difficulties)
• Circadian Rhythm - correlation not causation - PART 2


  E: Solomon (1993) concluded that high divorce rates in shift workers might be due to the strain sleep deprivation places on marriages and due to missing out on important family events.

  L: Thus suggesting the negative effects are caused indirectly rather than directly by the shift work. Suggesting that it may not be biological factors that create the adverse consequences associated with shift work.
• Circadian Rhythms - Shift the school day 


  P: Shifting the school day

  E: Research shows benefits for teenagers academic and behavioural performance when lessons start later in the day (Adolescent Sleep Working Group 2014).

  E: However, a later start is disruptive for parents & teachers, and teenagers may simply stay up later and still be exhausted.

  L: This suggests changing the school day may not be practical even though it may be desirable.
• A03 points of circadian rhythms?

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  A) ?

  
• Circadian Rhythms A03:


  +Positive Implications

  +Shift Work

  -Correlation not causation 

  -Shifting the school day

  -Hard to Generalise