Summary
Summary Circadian rhythms AQA A level Psychology Cornell style notes
- Course
- Institution
Detailed Cornell style notes of Circadian rhythms for AQA A level psychology
[Show more]
Seller
Follow
meganhughes
Content preview
CIRCADIAN RYTHMSBiological rhythms
Biological rhythms • All living organisms- plants, animals and people- are subject to
biological rhythms and these exert an important influence on the
way in which body systems behave
Endogenous • All biological rhythms are governed by two things- body's internal
pacemakers biological 'clocks', which are called endogenous pacemakers and
Exogenous external changes in the environment known as exogenous zeitgebers
zeitgebers • Some of these rhythms occur any times during the day(ultradian
rhythms)
Ultradian rhythms • Others take longer than a day to complete(Infradian rhythms) and in
Infradian rhythms some cases much longer(circannual rhythms)
• Circadian rhythm last for around 24 hours(circa is Latin for 'about'
Circadian rhythm and diem for 'day'). Two examples of circadian rhythms are the
sleep/wake cycle and core body temperature
The sleep/wake
cycle The sleep/wake cycle
• The fact that we feel drowsy when it's night-time and alert during the
day demonstrates the effect of daylight- an important exogenous
zeitgeber- on our sleep/wake cycle
• However the sleep/wake cycle is also governed by an
internal(endogenous) pacemaker- biological 'clock' called the
suprachiasmatic nucleus(SCN)
• The SCN lies just above the optic chiasm which provides information
from the eye about light
• Exogenous zeitgebers(light) can reset the SCN
• What if the biological clock was 'left to its own devices' without the
influence of external stimuli such as light
Michel Siffre
Siffre's cave study
• Michel Siffre is a self-styled caveman who has spent several
extended periods underground to study the effects on his. Own
biological rhymes
• Deprived of exposure to natural light and sound, but with access to
adequate food and drink, Siffre resurfaced in mid-September 1962
after two months in the caves of the Southern Alps believing it to the
mid-August
• A decade later he performed a similar fear to a 'free-running'
• If we had no idea whether it was night or day would we still fall
Jurgen Aschoff and asleep and wake up at regular times?
Rutger Wever(1976) • Research have tried to answer this question
Other research
• Similar results recorded by Jurgen Aschoff and Rutger Wever(1976)
who convinced a group of participants to spend four weeks in a
World War 2 bunker deprived of natural light
• All but one of the participants(whose sleep/wake cycle extended to
29 hours) displayed a circadian rhythm between 24 and 25 hours
• Both Siffre's experience and the bunker study suggest that the
'natural' sleep/wake cycle may be slightly longer than 24 hours but
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 or Stuvia-credit 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 meganhughes. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.53. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
76799 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now