Circadian Rhythms

    Cards (12)

    • What are the 3 types of biological rhythms?
      Circadian (once in 24 hours)
      Infradian (more than 24 hours)
      Ultradian (less than 24 hours)
    • What is an example of a circadian rhythm?
      The sleep/wake cycle
    • What is Siffre's sleep/wake cycle research?
      Spent 2 months in a cave in the southern Alps
      He was deprived of natural light and sound
      He came out of the cave in September 1962, thinking it was August
      Then spent 6 months in a Texan cave
      His free-running biological rhythm settled to a 25 hour cycle
      He still fell asleep and woke up at regular times
    • What is Aschoff & Wever's sleep/wake cycle research?
      Got people to spend 4 weeks in a WW2 bunker
      They were deprived of natural light
      All but one displayed a circadian rhythm between 24 and 25 hours
      One had a 29 hour cycle
    • What do Siffre's and Aschoff & Wever's suggest?
      The natural sleep/wake cycle may be slightly longer than 24 hours
      It is influenced by exogenous zeitgebers like daylight and meal times
    • What is Folkard's sleep/wake cycle research?
      Studied a group of people who lived in a cave for 3 weeks
      Went to bed at 11:45 and woke up at 7:45
      The clocks were put forward so they thought the day was 24 hours when it was 22 hours
      Only one person could adjust to the new regime
    • What does Folkard's study suggest?
      The free-running circadian rhythm is so strong that it can't be easily overridden by changes in the external environment
    • What is the 'practical application to shift work' strength of the sleep/wake cycle?
      Desynchronisation has negative consequences on night shifts
      Boivin - night workers have a circadian trough (reduced concentration) at 6am when mistakes and accidents tend to happen
      Knuttson - shift workers are more likely to develop heart disease due to stress and poor-quality sleep
      These may have real-world economic implications for how to manage worker productivity and improving understanding
    • What is the 'practical application to drug treatment' strength of the sleep/wake cycle?
      Circadian rhythm research has helped to increase the effectiveness of drug treatments
      Circadian rhythms coordinate some of the body's processes, which has lead to chronotherapeutics
      E.g. aspirin is most effective for heart attacks when taken at night because heart attacks are more likely to happen first thing in the morning
    • What is the 'practical application to shift work' weakness of the sleep/wake cycle?
      Studies looking at shift work use correlations so it can't be said that desynchronisation caused negative effects
      High divorce rates in shift workers may be due to the strain of deprived sleep and missing out on family events
      It may not be the biological factors that cause negative effects, it may be environmental factors
    • What is the 'individual differences' weakness of the sleep/wake cycle?
      Generalisations are difficult to make
      Research done by Siffre and Aschoff & Wever were both done on small samples so lack population validity
      Sleep/wake cycles can vary between people
      Duffy - some people prefer to sleep and wake up early and others late
      Siffre's study was when he was 60, and his internal body clock was slower than a previous study on himself
    • What is the 'shifting the school day' strength/weakness of the sleep/wake cycle?
      Some researchers think the school day should begin later due to hormonal shift patterns that cause teenagers' chronotype
      Evidence shows that academic and behavioural performance when lessons start later in the day
      Shows that circadian rhythms are strong and different, so do affect performance
      But... some critics say that it wouldn't reduce sleep deprivation, it would just make teenagers stay up later and be tired still