AO3

• Biological Rhythms Pros:

  • Evidence - Siffre (1975) found that the absence of light from staying in an underground cave with no clocks altered his circadian rhythm as he thought the date to be a month earlier --> case study
  • Evidence - Aschoff & Weber studied ppt in a bunker with only artificial light, their sleep/wake cycle settled into a longer hours of 25-27 hours highlighting the necessity of exogenous zeitgebers
• Biological Rhythms Cons:

  • Individual Differences - Duffy (2001) found that 'morning people' prefer to go to bed early (6 AM - 10 PM) whereas 'evening people go at (10 AM - 1 AM) showing innate differences

  Pros:

  • Morgan bred hamsters, so their rhythm was 20 hours instead. SCN neurons from these hamsters were transplanted onto normal hamsters, and they adapted to a rhythm of 20 hours, suggesting that SCN (endogenous pacemakers) are important
• Ultraradian/Infradian Pros:

  • Research support -Reinburg(1967) examined a woman who spent 3 months in a cave with little light, her cycle shortened from 28 to 25.7 days supporting exogenous zeitgebers
  • Further support - Russell (1980) found that sweat from one woman to another on the upper lip can synchronise menstrual cycles(supports exogenous zeitgebers)
• Ultraradian/Infradian Cons:

  • Individual Differences - Tucker's lab study found differences in stages 3 and 4 of sleep, and can't be situational, but biological --> external factors
  • Lacks ecological validity - ppts are subjected to specific levels of control eg. monitors, which could be invasive and disrupt ordinary sleep --> difficult to draw conclusions