circadian rhythms

• biological rhythms

  distinct patterns of changes in body activity that conform to cyclical time periods
• what are biological rhythms regulated by?

  • endogenous pacemaker - internal body clocks etc
  • Exogenous zeitgebers - external changes in the environment
• what is the master circadian pacemaker and where it located?

  superchiasmatic nuclei located in the hypothalamus - environmental cues continually reset this clock through photoentrainment
• what is Siffre’s cave study?

  • he spent several extended periods (2 and 6 months) in dark caves to study the effects on his own biological rhythms
  • was deprived from natural sunlight and sound
  • his free running biological rhythm stretched to about 25 hours though he slept and woke up at a regular schedule
• what was Folkard et al study

  • 12 people lived in a dark cave for three weeks
  • they would go to sleep at 11:45pm and woke up at 7:45
  • unknown to the ppts the researcher sped up the clock so a day was only 22 hours. only one person adapted
• evaluation weakness - case studies

  • a single / small group case study, one ppt only - generalisations may not apply to others due to individual differences
  • ages may also have been a factor as results may be limited to a similar age group
  • other variables like air pressure, temperature etc may interfere
• strength - economic implications

  • shift work has been found to lead to desynchronisation of circadian rhythms and can lead to adverse and physiological effects
  • Boivin - night shift workers suffer a concentration lapse at 6am which increases the likelihood of accidents
• real world application -

  • chronotherapeutic -> is the study of how timings affect drug treatments and as the circadian rhythm affects digestion, heart rate and hormones among other functions, this can be taken into account when consuming drugs
• reductionist ->

  • oversimplifies the workings of the human biology which is more complex - the SCN is evidently not the only biological clock as other studies have shown that there are other oscillators in the body that appear to regulate biological rhythms through other means and explaining circadian rhythms are simply dictated by the SCN and pineal gland connection