Biological Rhythms Flashcards
Define a circadian rhythm with an example.
A bodily rhythm that lasts roughly 24 hours.
E.g. sleep-wake cycle.
What is an exogenous zeitgeber?
An external factor that influences the circadian rhythm in question.
E.g. light, temperature.
What is an Endogenous Pacemaker?
Internal body clocks or time keepers that influences the circadian rhythm.
Outline Siffre’s study.
He spent up to six months in a cave, when he came out, his circadian rhythm had been effected to such an extent that he thought it was a month earlier than it was.
Give an advantage of the Circadian Rhythm.
+Supporting evidence from Folkard.
A clock in a cave was slowly sped up unbeknownst to participants resulting in them having a circadian rhythm of 22 hours. No pps could comfortably adjust, circadian rhythm may be affected by endogenous zeitgebers.
Give a disadvantage of circadian rhythms.
-Circadian rhythms differ on an individual basis.
Duffy et al suggested the difference of ‘morning people’ and ‘evening people’.
-Extraneous variables may confound the results.
Czeisler found that artificial light can influence the circadian rhythm, Siffre’s use of light may invalidate the findings.
Define an infradian rhythm and give an example.
A bodily rhythm lasts longer than 24 hours.
E.g. the menstrual cycle.
Give an advantage of infradian rhythms.
+Supporting evidence from McClintock for the role of Exogenous zeitgebers.
He found that pheromones of other females synchronised their menstrual cycles, however this does not discredit other exogenous factors.
Give a disadvantage of infradian rhythms.
-Methodological flaws in research into infradian rhythms.
Small sample of McClintock’s study, therefore it has low population validity.
Define an ultradian rhythm and give an example.
A bodily rhythm that lasts less than 24 hours.
E.g. stages of the sleep cycle.
Outline stages of the human sleep cycle.
-Stages 1 and 2 and ‘light sleep’ stages.
-Stages 3 and 4 are ‘deep sleep’ stages.
-Stage 5 is REM (or dream) sleep.
Give an advantage of ultradian rhythms.
+Supporting evidence from case studies.
Randy Gardner stayed awake for 264 hours and he only recovered 1/4 of the lost sleep. This demonstrates the flexibility of ultradian rhythms.
Give a disadvantage of ultradian rhythms.
- It uses artificial methodology.
it was carried out in a controlled way where participants may have difficulty sleeping. It has low ecological validity.
