CIRCADIAN RHYTHMS

• What is a biological rhythm?

  a change in body activity that follows a particular cycle
• what is a circadian rhythm?

  a biological rhythm that lasts around 24 hours
• example of a circadian rhythm?

  the sleep/wake cycle
• what governs our circadian rhythm?

  exogenous zeitgebers and endogenous pacemakers
• what was Siffres procedure to test circadian rhythms?

  spent 7 months a in dark cave, didn’t know what the time was the entire time
• what were the results of siffres research?

  his free running circadian rhythm was 25 hours

  he had a regular sleep/wake cycle
• what was Aschoff’s procedure?

  participants spent 4 weeks in a WW2 bunker, deprived of natural light
• what were the results of Aschoff’s experiment?

  all but one of the participants displayed a circadian rhythm between 24 and 25 hours
• What was Folkards procedure?

  12 people lived in a cave for 3 weeks

  agreed to go to bed at 11:45 pm and wake up at 7:45 pm

  researchers secretly sped up their clock so each day was 22 hours
• what were the results of Folkard’s experiment?

  none of the participants could adjust to the 22 hour cycle
• strengths of research

  practical application to shift work - found they experience a concentration lapse around 6am so mistakes and accidents are more likely. research can have economic implications to manage worker productivity

  Drug Treatments - research shows there are certain time in the day when drugs are more effective, led to guidelines on certain drugs
• limitations of research

  individual differences in CR research- been found ranging from 13-65 hours. Research found that people are either more active in morning or evening but Teenagers CR are 2 hours behind adults. these variations makes generalisations more difficult

  Case studies and small sample sizes - often use small group, could be participant variables

  confounding variables - even when deprived of natural light they still had access to artificial light which was turned off when sleeping. could alter CR