circadian rhythms

• what is a circadian rhythm

  circadian rhythm - a biological rhythm that lasts 24 hours, like the sleep/wake cycle
• what controls the sleep/wake cycle

  exogenous zeitgebers - external environmental cues that regulate our body clock

  endogenous pacemakers - internal mechanisms that regulate our body clock
• what was siffre's research

  siffre:

  • 7 months in a dark cave without knowing the time
  • free running circadian rhythm was 25 hours
  • had a regular sleep/wake cycle
• what was aschoff's research

  aschoff:

  • participants spent 4 weeks in ww2 bunker
  • no natural light
  • all but one had circadian rhythm of 25-25 hours
• strengths of research

  strengths:

  • time of work shifts, concentration lapse at 6am making mistakes more likely, can avoid this
  • drug treatments, certain times in the day make treatment more effective
• limitations of research

  limitations:

  • small sample sizes in research, not generalisable
  • confounding variables, no natural light but artificial light can still interfere cycle
• what is a superchiasmatic nucleus

  superchiasmatic nucleus - central pacemaker of circadian rhythm and regulates most body rhythms

  decoursey - destroyed SCN of chipmunks and returned them to habitat, where their sleep cycle was ruined and they were killed by predators