Biological Rhythms: Circadian Rhythms Flashcards
(14 cards)
what is a biological rhythm?
- distinct pattern of changes in body activity that conform to cyclical time periods
what are the 3 types of biological rhythms?
- circadian
- ultradian
- infradian
what is a circadian rhythm?
a type of biological rhythm subject to a 24hr cycle, which regulates a number of body processes
- these include sleep/wake cycle and changes in the core body temperature
- they are both affected by endogenous pacemakers and exogenous zeitgebers
what is an endogenous pacemaker? (and an example)
internal body clocks
- SCN (suprachiasmaticnucleus)
what is an exogenous zeitgeber and give an example?
external changes, cues, in the environment
- e.g. light
what does research into circadian rhythms include?
- ‘free running’ body clock which refers to the removal of light as a time cue and observing the effects on sleeping patterns
who are the researchers involved in the research into circadian rhythms?
- Siffre
- Aschoff and Wever
- Folkard et al
what did Siffre do?
- cave explorer who spent extended periods of time underground
- wanted to investigate the effect of this on his free-running circadian rhythm
- deprived of natural light and sound with access to food and drink
- kept a diary of his sleep and wake patterns
- initial sleep patterns were erratic and then settles down to a regular rhythm
- his natural circadian rhythm without exogenous zietgebers was 25 hrs
- spent two months in a cave but according to his days he had only been there for 1.5 months (he resurfaced at mid september but believed it was mid august)
- repeated a decade later and spent 6 months in a cave(Texan), recording the same results
what did Ashoff and Weaver do?
- 4 weeks in a WW2 bunker
- 26 ppts
- deprived of light
- all but one ppt displayed circadian rhythms of 24-25 hrs
- one ppts circadian rhythm extended to 29hrs
what did Folkard et al do?
- 12 people lived in a cave for 3 weeks
- went to bed at 11:45pm and rose at 7:45am
- researchers sped up the clock so 24 hrs went to 22 hrs
- only one ppt was able to adjust
what are the evaluations for circadian rhythms?
+ research into circadian rhythms has given insight into the effects of desynchronisation
+ practical application to drug therapy
- use of case studies and small samples = generalisations are difficult to make
explain this evaluation: + research into circadian rhythms has given insight into the effects of desynchronisation
Point: A strength of research into circadian rhythms is that it gives us insight into the effects of desynchronisation.
Evidence: For example, Boivin (1996) has shown that night workers experience reduced concentration around 6AM, making mistakes and accidents more likely to happen.
Explain: Similarly, further evidence revealed that shift workers are three times more likely to develop heart disease than those who work typical work patterns.
Link:Therefore, such findings can have real-world economic implications as employers have to consider how best to manage worker productivity.
explain this evaluation: + practical application to drug therapy
Point: Another strength of research into circadian rhythms is that it has been used to improve medical treatments.
Evidence: For example, research has shown us that circadian rhythms co-ordinate a lot of the body’s basic processes, such as heart rate, digestion and hormone levels.
Explain: This is important in chronotherapeutics, which is how medical treatments can be administered in a way to best match a person’s biological rhythms, such as taking aspirin at night to treat heart attacks.
Link: Therefore, this shows how circadian rhythm research has helped increase the effectiveness of drug treatments.
explain this evaluation: - hard to make generalisations
Point: A limitation of research into circadian rhythms is that it is difficult to make generalisations.
Evidence: For example, Siffre’s study consisted of only himself as the sample and research has shown that there are major individual differences in sleep/wake cycles (between 13 to 65 hours).
Explain: These differences aren’t just between individuals, but also vary with a person as they age, as Siffre observed his own sleep/wake cycle slowed down as he got older.
Link: Therefore, it is difficult to make meaningful generalisations regarding sleep/wake cycles based on the research that was done.
