Biological rhythms : Circadian rhythms

Question 1

1. Research into the sleep/wake cycle: Siffre’s case study

Answer 1

• siffre, 60, spent 2 months in an underground cave in Southern Alps to study biological rhythms
• no access to light and sound (exogenous zeitgebers) but had adequate food, drink and artificial light
• same thing conducted a decade later in Texas, for 6 months
• his biological rhythm settled into a just over the usual 24 hour cycle (25 hours) but he continued to fall asleep and wake up on a regular schedule
  Conclusion: study shows that endogenous pacemakers have a stronger influence on our circadian rhythms because without his exogenous zeitgebers he could wake and sleep in approximately the same cycle

Question 2

Evaluation

Answer 2

• small sample size
• poor control of extraneous variables
  + research support

Question 3

• small sample size

Answer 3

the study uses a small sample size so its therefore difficult to make generalisation. for example siffre was observed in a case study at the age of 60 which means his internal clock was a lot slower than when he was a young man

Question 4

• poor control over extraneous variables

Answer 4

the study failed to gain control over extraneous variables. researchers such as Siffre still had access to artificial light so therefore we cannot be certain these didnt impact their circadian rhythms

Question 5

+ Research support

Answer 5

Aschoff and Wever (1976) studied a group of people who spent 4 weeks in a WW2 bunker deprived of natural light. All but one (whose sleep/wake cycle extended to 39 hours) displayed a circadian rhythm of 24-25 hours

Question 6

2. Core body temperature

Answer 6

• evidence suggests that body temperature is linked to our cognitive abilities - the warmer we are internally, the better our cognitive performance
• core body temperature was the lowest around 4am (36) and highest around 6pm (38)

Question 7

Research evidence

Answer 7

Folkard et al (1977)
* found that children who were read stories at 3pm had better recall than those who heard the same story at 9am

Question 8

Evaluation

Answer 8

+ Practical application
+ Medication

Question 9

+ Practical application

Answer 9

circadian rhythms are important for how well we concentrate. night workers engaged in shift work, experience a period of reduce concentration at around 6am. this means employers could be made more aware of the likelihood of accidents and mistakes happening during this time

Question 10

+ Medication