RESEARCH

• KEY RESEARCHERS?

  • De Coursey
  • Siffre
  • Miles et al
  • Campbell and Murphy
• DE COURSEY?

  • investigated influence of SCN in animal studies
  • functionally removed SCN in 30 chipmunks
  • released back into natural habitat
  • more chipmunks with SCN removed died than control group
  • failure of SCN to regulate sleep/ wake cycle caused them to stay awake at night
  • higher risk of predation
  • SCN (endogenous pacemakers) vital at regulating biological rhythms such as sleep/ wake cycle to aid survival
• DE COURSEY EVALUATION?

  • cautious when extrapolating
  • animals have less social cues affecting sleep/ wake cycles
  • reduces generalisability
  • ethical issues (not protected from harm)
• SIFFRE?

  • shows presence of endogenous pacemakers in sleep/ wake cycle
  • circadian rhythm remained very close to 24 hour cycle
  • even without aid of exogenous zeitgebers
  • e.g. natural light/ noise
• SIFFRE EVALUATION?

  • not representative
  • case study
  • cannot be generalised to wider population
  • reduced temperature/ artificial light may have acted as exogenous zeitgebers
  • affected biological rhythms
  • hard to measure relative influences of endogenous pacemakers and exogenous zeitgebers on circadian rhythm
• MILES ET AL?

  • case study
  • 28 year old psychologically normal blind man
  • biological rhythm was 24.9 hours
  • despite social cues from environment
  • had to regulate using sedatives
  • suggesting social cues not as powerful as light as an exogenous zeitgeber regulating circadian rhythms
• CAMPBELL AND MURPHY?

  • light very powerful exogenous zeitgeber
  • woke 15 participants at various times
  • projected light onto back of knee
  • sleep/ wake cycles began to change
  • one altered by 3 hours
  • light powerful exogenous zeitgeber which can entrain biological rhythms
  • also detected by skin not just eyes
• CAMPBELL AND MURPHY EVALUATION?

  • real world application
  • light on skin can help regulate circadian rhythms
  • assist blind/ visually impaired
  • help night shift workers regulate sleep/ wake cycle
  • suggestions to recreate night conditions