Siffre 1975

• Siffre (1975) aim


  to investigate whether humans have a biological clock, without effects from exogenous zeitgebers
• Siffre (1975) sample


  number: 1

  who: himself
• Siffre (1975) procedure


  Siffre isolated himself in a dark cave for 63 days, announcing to his team whenever he wakes, sleep, ate, his pulse, and counting seconds for 2 mins
• Siffre (1975) findings


  on average, his sleep schedule was 26 hours

  his perception of time slowed down significantly
• Siffre (1975) conclusion


  humans have a 26 hour sleep-wake cycle, the exogenous zeitgeber of light made us adjust to 24 hours
• Siffre (1975) critique


  G - technically a case study, it was only him, cannot generalise

  R - can be replicated and on a large scale, but there would then be an ethical issue

  A - can be applicable, helps us understand effect of exogenous zeitgebers on endogenous pacemakers

  V - low internal validity, the artificial light he had may have acted as a confounding variable

  E - not ethically concerning, no serious harm done, maybe messed up sleep schedule