Summary
Circadian Rhythm summary sheet
This is a very rich and in-depth summary for Biopsychology - circadian rhythm section
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Content preview
Circadian RhythmsAll living organisms have biological rhythms which impact on our body’s systems.
Define the following key terms (use your own words)
Biological rhythms:
Distinct patterns of changes in body activity that conforms to cyclical time periods.
Biological rhythms are influenced by internal body clocks (endogenous pacemakers) as
well as external changes to the environment (exogenous zeitgebers)
Circadian rhythms:
A type of biological rhythm, subject to a 24-hour cycle, which regulates a number of body
processes such as sleep/wake cycle and changes in core body temperature
Exogenous
zeitgebers: External changes to the environment
Endogenous
pacemakers Internal body clocks
The sleep/wake cycle is a key example of circadian rhythms- we feel drowsy and sleepy at nighttime and
alert during the day, these are key examples of endogenous pacemakers.
Many studies have been conducted to assess the sleep/wake cycle to see what would happen if the
biological clock had no exposure to external factors.
Key research: Siffre’s cave study
Summarise the research and findings using 4 bullet points.
• Michael Siffre was a self-taught caveman who used to stay underground for long periods in order to
study the effects of his own biological rhythms
• He stayed underground for around 2 months, with a lack of sunlight and sound but enough food and
drink
• A decade later he performed a similar study, this time 6 months in a Texas cave
• In each case, his ‘free-running’ biological rhythm settled down to one that was beyond usual 24 hours- 25
instead, although he woke up and fell asleep on a regular schedule
, Other research
(use either Aschoff and Wever or Folkard)
Similar results were recorded by Aschoff and Wever, who convinced a group of participants to spend four weeks in a WWII
bunker deprived of natural light. All but one of the participants (whose sleep/wake cycle extended to 29 hours) displayed a
circadian cycle between 24 and 25 hours.
Both Siffre and the bunker study suggest that the ‘natural’ sleep/wake cycle may be slightly longer than24 hours but that it
is entrained by exogenous zeitgebers associated with our 24- hours day (such as the number of daylight hours, typical meal
times, etc.
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 shimsham. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £5.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67096 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now