This document provides detailed A01 notes and A03 evaluation into circadian rhythms and works of Siffre for the biopsychology module, these notes are clear, and easy to follow. The A03 contains a deep explanation of both strengths and limitations to the theory/study, along with evidential support...
These refer to biological rhythms that are subject to 24 hour cycles which
regulate a number of body processes such as the sleep/wake cycle and
body temperature.
The sleep wake cycle
Feelings of drowsiness when its night, and alertness in the day demonstrates the effects of daylight
(exogenous zeitgeber). Sleep/wake cycle is governed by an internal endogenous (endogenous
pacemaker) a biological clock called the 'superchiasmatic nucleus' (SCN) , this co-ordinates the
activity of circadian rhythms.
Siffre's cave study
Aimed to see the effects on biological rhythms if it was 'left to its own devices'
without the influence of external stimuli (exogenous zeitgeber) such as light. Siffre
spent 2 months in a cave with no natural light and adequate food. He resurfaced in
september, yet thought it was august. Showing how his 'free running' biological
rhythm settled down to one that was just beyond 24 hours (25 hours), though was a
able to maintain a regular sleep/wake cycle, he did not perceive the circadian rhythm
as longer, leading to an inaccurate estimation of time.
Wever(1976)
Similar results conducted , convinced group of participants to spend 4 weeks in ww2
bunker deprived of natural light, all but one participant showed a circadian rhythm of 25
hours. Both studies suggest that the 'natural' sleep/wake cycle is slightly longer than 24
hours (without light), but a 24 cycle is entrained in us by exogenous zeitgebers associated
with a 24 hour day e.g. number of daylight hours, mealtimes etc.
Evaluation of Circadian rhythms
One strength of research into circadian rhythms is it provides understanding of the consequences
that may occur if said rhythms are desynchronised. E.g. night workers experience a drop in
concentration at 6am, meaning mistakes are more likely to occur. Further, late night shift work and
poor relationship seem to link for example, are 3x more likely to have heart disease than those with
typical work schedules. Therefore this research into sleep/wake cycle may have economic
implications in regards to employ productivity.
Counter-point: However, studies into the effects of shift work tend to use correlational methods
which assume causation, whereas this does not consider other factors. For example,
(Solomon)concluded that high divorce rates in shift workers may be due to the strain of deprived
sleep and lack of attendance to family events , suggesting it is not solely biological factors which
create adverse consequences in shift work employees.
Limitation: Studies of the sleep/wake cycle and free running biological rhythms usually include a
case study like that of Siffre, or small group samples like in Aschoff and Wever's bunker study. This is
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller benjamincatling. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £4.19. You're not tied to anything after your purchase.
